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MG Midget and Sprite Technical - More 5 speed woes... The Saga Continues

Some of you will know about my woes doing a 5 speed conversion on my Frog.
A brief description of the none-standard route I have taken.
1275 midget engine, tuned somewhat.
A 1275 Midget clutch and flywheel using a hybrid clutch plate.
The diaphragm clutch modified to remove the bearing face so concentric clutch release bearing pushes on the diaphragm fingers.
Antec racing bell housing. (This was meant to enable an A series engine to be mated to a Midget 1500 gearbox).
A Midget 1500 gearbox to Type 9 gearbox conversion plate from Canley Classics.
A SAAB 9000 Concentric slave cylinder inside the bell housing.

After much agro with the setup involving removing and replacing the engine several times, I finally got to try it out on the road today. Everything is ok apart from clutch slip. Lots of it. Not so noticeable in first but after that it's pretty bad.

The clutch pedal seems quite heavy, certainly heavier than standard. Also the bite point is quite high suggesting the slave cylinder is not being allowed to release sufficiently.

I thought it might be the adjustment at the master cylinder end so I adjusted it to give maximum play. Before I adjusted it, it was quite solid, now it is slack.

It didn't improve the clutch slip at all.

So, can any of you suggest what might be wrong?

Rob


Rob aka MG Moneypit

As the clutch plate and the cover plate were not designed to be used together, it might be they are simply not matching. 'Non-slip' requires a load partly determined by the strength of the cover-plate's sprung fingers and partly by the distance between the 'disengaged' position of the cover-plate and the flywheel. That distance needs to be shorter or the clutch plate thicker.
Nick Nakorn

Before I put the engine and gearbox back in the car I measured the distance the concentric slave moved. I ran a pipe from the clutch master to the clutch slave whilst the engine/gearbox were lying next to the car. As built, before it was connected up there was an 8mm or so gap between the face of the release bearing and the fingers. Once connected, fluid moved the release bearing until it contacted the fingers. Once bled, depressing the clutch pedal pushed the fingers to disengage the clutch. Releasing the pedal released the fingers but the release bearing remained in contact with them. I know this is normal, concentric slaves operate like that.

In contrast, the carbon clutch bearing in the normal Midget clutch is not meant to remain in contact so has to be pulled back somehow. How is this done? Is it the master cylinder and pedal assembly that does this?

I have friends who have put Type 9's in Midgets and they have both gone from the normal setup to a concentric setup using Burton supplied systems. Both of them have used the same dual master cylinder as me, but don't have this problem.

It's as though the master cylinder isn't allowing enough fluid back.

Rob

Rob aka MG Moneypit

The distance between the face of the release bearing and the fingers will have no effect on clutch slip, only on the effectiveness of the clutch disengagement.
Nick Nakorn

I'm guessing the heavy clutch pedal is simply due to the concentric slave.

Assuming there is no oil or grease on the clutch plate it could be a mismatch between the clutch cover and plate, are they the exact same diameter? Was the flywheel refaced? Is the new clutch plate the same diameter as the old diameter?
Daniel Stapleton

We alway recommend fitting a std Pinto clutch assembly with the Type 9 conversion. Have only used the Burton concentric clutches, and set them to about 5mm from the fingers to release bearing, to allow for clutch wear. Not sure if the Saab unit has a greater movement for pedal pressure / position. Can you adjust the operating rod in the m/c, i.e. wind it out of the cylinder ?.
J L HEAP

The flywheel and clutch are the same as when it had a ribcase gearbox on the engine. The driven plate has been replaced by a hybrid supplied by David Manners. It looked identical to the standard 1275 one, just the centre was different.

I thought about the length of the push rod. I adjusted it to make it as short as possible but there was no noticeable difference to the clutch slip.

Does the pushrod length matter on the clutch? It does on the brake but I didn't think so on the clutch.

Rob
Rob aka MG Moneypit

Had a good think overnight and there could be one of two possibilities.

1/ The mechanical force from the fingers is insufficient to push the release bearing back far enough to let the clutch engage fully.

2/ The piston in the master cylinder cannot move back sufficiently to allow enough fluid to return so allowing the release bearing to move far enough back to allow the clutch to fully engage.

If 1/ is the cause then a stronger clutch diaphragm spring might cure it.

If 2/ is the cause there should be some residual pressure in the system.

I can check 2/ by releasing the bleed nipple to see if any fluid is released indicating the system is not at rest.

If 2/ is the problem it could be the length of the pushrod at the master cylinder. If it's not the pushrod length then the master and slave must be incompatible and I'm back to the drawing board.

Rob
Rob aka MG Moneypit

Rob, just chucking an idea out there...

Master not large enough? Therefore not displacing enough fluid to move slave correctly?

This might also give you the heavy pedal?

This might be waffle. I have only just got up and not had any coffee yet!! :-D

Malc.
M Le Chevalier

Well I'm not sure, the master does displace enough fluid to fully disengage the clutch but when the pedal is released it seems the slave doesn't return enough fluid.

I can't think of anything but the two points I made in my earlier posting.

I'm getting really frustrated by this project and considering giving up and buying the required bits from the usual suspects, which ,maybe, is what I should have done in the first place!!

Rob
Rob aka MG Moneypit

I think , re setting the gap between the release bearing and fingers could be the way to go with your set up. As you say the clutch is slipping so the bearing must still be engaged.
IMO the D Manners clutch set up as with Midget and Minor is a poor design, and as I say the Ford clutch is better suited to the concentric clutch set up. We have taken out over 20 of these D.Manners kits and replaced as above with much better results.
Normally the m/c is 1" and the slave .75, this works very well and gives a very light pedal.
J L HEAP

JLH, when I originally installed the SAAB 9000 concentric there was an 8mm gap with the slave fully retracted. It's not that the release bearing is fully retracted and still in touch with the fingers, there is 8mm retraction space it could use. Somehow, either the clutch diaphragm doesn't have enough pressure to push back the release bearing or something is preventing enough fluid to be returned to the mc reservoir.

I'm just about to go back in the garage to see if there is any residual preassure in the hydraulics. I can see this turning into another engine out job.

Rob
Rob aka MG Moneypit

Bleed out some fluid and see what happens
J L HEAP

Some thing you may consider is using a tilton clutch master cly, they come in various sizes but there fully adjustable, and are not very expensive

This is the joy of modification, its just trial and error, the more modification the more hassle

When I did my datsun 5 river gate kit with the frendinza aluminum fly wheel and the high torque starter...it was certianly a challange even tho all the parts parts where supposed to be plug and play

It just takes patiance and dedication to the cause and just plan on alot of BS
Prop and the Blackhole Midget

Maybe a partially seized clutch pedal pivot? It is surprising how much impact this van have both on how heavy the pedal feels, and also on how 'snappily' it returns when you release the pedal
Guy W

Your correct guy,

Its crazy to see those clevis pins oval out there housings

Prop
Prop and the Blackhole Midget

I had a look today. I undid the slave bleed screw to see if there was any excess pressure in the system. There wasn't any. No spurt of fluid, in fact only enough leaked out to wet the nipple.

BTW, the last sentence above is an excerpt from my forthcoming book "50 shades of Gray Primer".

I drove the car anyway to see if anything had changed. It was still the same.

So tomorrow, if I can get some garage time, I will check the pushrod length and maybe shorten one of my spares.
I will also take off the clutch pedal and check for wear and binding.

I'm not too hopeful and expect I will be taking the engine and gearbox out again soon.

Thanks for all the advice. Watch this space.

Rob


Rob aka MG Moneypit

Hmm. Intertesting. I've never primed a nipple before use.
Lawrence Slater

Not had a chance to get in the garage yet but still having a good ponder now and again.

I was wondering why the clutch felt so heavy and have come up with the idea that the slave is moving too much. The pedal, master and slave all form a type of lever so if the pedal is hard to move it implies the slave is moving too much. If the pedal was light it would mean the slave was moving a little. The theory of levers.

Now, if I have moved the fingers too much maybe I have damaged the diaphragm spring? I don't think that I have bent the fingers because it would be harder to disengage the cluctch, which is not the case.

I have still got to check the pushrod length and whether or not the pedal is seized, but I don't think it is either because there is a small amount of clearance on the pushrod and the system doesn't seem to have any residual pressure.

Rob
Rob aka MG Moneypit

<< Maybe a partially seized clutch pedal pivot? >>

Rob,

Do check the pedal pivot, a friend of mine took out the engine from a 3.4 Jaguar to replace a slipping clutch, replaced it and found that it still slipped!!

Removing, cleaning and lubricating the clutch pedal pivot sorted the problem!!

Richard
Richard Wale

It is possible to 'over throw' the clutch, especially with a concentric conversion which is why it can be necessary to fit a shorter clutch push rod or fit a stop to it.
Daniel Stapleton

Agreed Daniel.
J L HEAP

Thanks Daniel and JLH. I took the pushrod off and shortened it by a little less than 1/4". Rounded the end with a file and put it back. I had to re-adjust the pushrod length effectively taking back a lot I had cut off. There is now a good 2mm free play. The clutch pedal is freely moving on the pivot.

It did improve. Slip is now only noticeable in 3rd ( and above but my road isn't long enough to get into 4th/5th).

Also, after my initial run I let the engine warm up fully and there seemed to be further improvement, though still slipping in 3rd, when I tried it again.

What you say about the pedal throw is interesting. I think later Mk's have a stop built into the pedal. Is that so?

Is it possible to drill a hole closer to the pivot point for the pushrod connection to the pedal. This would have two benefits. 1/ less throw on the slave and 2/ lighter pedal operation.

Rob
Rob aka MG Moneypit

The burton concentric slave in my car would have a better action if I changed the size of the master. Since I haven't I have a very short in/out action that I'm used to and that cannot overthrow the clutch.

If you have been overthrowing the clutch it's possible the diaphragm fingers haven't been fully returning.

I made a short master push rod by cutting a standard rod and threading it for a threaded fork.


Daniel Stapleton

So if I have been overthrowing the slave how can I get it back a little?

I'm using the original Frogeye pushrods which are adjustable in the same way as your modified example, although it is a little longer than yours.

Is there a pressure relief hole in both bores of the dual master cylinder? I know there is in the brake side for disc brakes but is there also one in the clutch side?

If there is, wouldn't the slave reposition itself as soon as this hole was uncovered when the clutch pedal is released?

Why do things have to be so complicated and why do I always fall foul of them?

Rob
Rob aka MG Moneypit

Make a temporary pedal stop so you cannot overthrow the pedal. If you make this adjustable then you may find a correct position. We use 0.75 master cylinders for the clutch and have not encountered any issues.
J L HEAP

Overthrow is caused when too much fluid is pumped by a single stroke of the maser cylinder, for the distance required to be moved by the slave piston. The 1275 and later master cylinders are (conveniently)matched to the SAAB 9000 and the Ford Concentrics. One can alter the stroke of the master cylinder buy using an adjustable m/c pushrod, but this shouldn't really be necessary.

But beware the earlier master cylinders which pump a slightly larger quantity of fluid per stroke (they were matched to a larger bore conventional slave cylinder). These would need an adjustable master pushrod to allow for adjustment.

(As an aside, changing the Slave pushrod length normally has no effect on overthrow, it simply alters the portion of the slave cylinder that the piston operates along)

I am not convinced the problem is overthrow in this instance. The concentric slave bearing should remain in very light contact with the clutch fingers when released. It is only the reaction force from the fingers that pushes it back; there is nothing to pull it any further away and that is how it is designed.

BUT maybe there is something that is blocking the concentric thrust bearing from moving back so it is maintaining pressure on the clutch fingers, causing the slippage. Some possibilities are:
The master cylinder piston not moving back freely,
The concentric slave mounted too close to the clutch so that there is insufficient reserve clearance, maybe it has excess thickness of spacers behind it,
The Gearbox input shaft splined section not long enough, preventing the driven plate from moving back from the flywheel
Guy W

The SAAB 9000 slave I am using has an effective area of 0.426 sq inches (according to AP Racing website). The 3/4" bore of the master cylinder gives an area of 0.601 sq inches.

I think that means if the master pushrod moves 1" the slave moves 1.4" which is what makes overthrow more likely and a heavier feel to the clutch pedal.

Any one know what the effective area of the Burton concentric that is usually used?

Is the leverage of the Frogeye clutch pedal different from later?


Rob
Rob aka MG Moneypit

"The master cylinder piston not moving back freely" is a possibility.

"The concentric slave mounted too close to the clutch..." is not the problem because in the fully retracted position I made sure there was about 8mm clearance. I saw this clearance dissappear as I bled the clutch first time leaving the release bearing in contact with the fingers.

"The Gearbox input shaft splined section not long enough..." is not the reason because if the driven plate moved off the splined section it would surely just spin with no drive at all.

I think the first is the most likely, although I don't like it because it means engine out once again.

Rob
Rob aka MG Moneypit

It is possible to overthrow the Ford Concentric with a standard clutch master and master pushrod and a shortening the push rod is an effective solution.

What happens is that with the standard clutch pedal pressed about half way to the floo, the clutch is fully disengaged. However, it's easy to continue pressing the clutch pedal, till it reaches the floor and overthrow the clutch and damage it. From memory, shortening the push rod lowers the pedal position, in comparasion to where it might normally be positioned. Consequently, there is less room between the clutch pedal and the floor, so less clutch movement and full movement (when the pedal is on the floor) so the clutch cannot be overthrown. A pedal stop will prevent the clutch pedal from achieving full travel and meeting the floor so likewise limits travel but does not move the position of the clutch pedal in the top position.

It's easy to establish if the clutch can be overthown by finding out how far from the floor the pedal is when full disengagement of the clutch is achieved. If it's achieved and there is still an inch or so from the pedal to the floor then there is a risk of overthrow.
Daniel Stapleton

The spring on the clutch pedal pulls the rod away from the piston in the master and makes the pedal high. If you have a short pushrod doesn't it mean there is more free travel before the pushrod pushes the piston so the stroke of the pedal that actually moves fluid is less.

I think you can do one or the other but not both. i.e. either shorten the pushrod OR use a pedal stop.

Wouldn't altering the leverage ratio of the pedal do the same? Where the pushrod attaches to the pedal there is a hole with a clevis pin. Couldn't I drill a new hole closer to the fulcrum and achieve the same (i.e. less stroke) and at the same time get a lighter pedal action thanks to the greater leverage?

Rob
Rob aka MG Moneypit

When I set mine up - I use a Ford concentric, I made up a temporary setup with a clutch pipe line to the engine and gearbox out of the car, on the garage floor. I could then check the travel and free movement of the concentric slave as I pressed the pedal in the car (or as the AA pressed the pedal)

I was somewhat surprised to find that it moved the required 11mm, no more and no less. I thought that was convenient and maybe there was some sort of universal standard so I needn't have bothered. The only thing that may be relevant is that I don't use those springs in the footwells that fasten to the pedals. Does anyone use them?

Good, Rob, that you have the required 8mm free play. That rules that out! What I meant by the splines being too short is that on some input shafts the splined length doesn't extend far enough back along the shaft towards the gearbox. Not that they weren't long enough going forwards! It depends which version of the T9 you have got hold of.
Guy W

You can have a short push rod and a pedal stop if you want.

If you remove the pedal box cover and look at the position the pedal is in and then envisage it if the rod is shorter you will see that the total amount of travel is reduced. The shorter rod physically moves the static position of the pedal.

I don't recall what the total travel I had with the Burton concentric slave was and is. I do know that it produced enough travel to overthrough the clutch.
Daniel Stapleton

Daniel, mine isn't a Burton set up. I use a Ford Fiesta slave and turned the mount for from a billet of alumininium from dimensions that I had calculated.
Guy W

Guy, the splined area is well within the plane of the driven plate so I don't think that is the problem either.

Daniel,I think we are saying the same things using different words.

As a temporary measure I could strap a piece of wood to the clutch pedal to act as a stop. I'll see what that does but I may have to wait till next weekend so I can do it in daylight.

Just in case it is the slave I've ordered a Mondeo one off eBay. If I need to take out the engine again I'll replace the SAAB with the Mondeo. I should have used a Ford one in the first place. They are half the price of the SAAB ones.

Just one last question (for now). Is it possible to weaken the diaphragm spring with too much overthrow?


Rob

Rob aka MG Moneypit

I swapped my knackered Saab one for a Ford Granada one after it broke on me in France in 2013

It meant I had to it a different packing piece but a short time on my friend's lathe sorted that

I set mine so it had 11/12mm free movement and found it has a far lighter action

In traffic NOW I can easily sit with a (naughty) foot on the pedal waiting for the time to move coming up

The Saab one worked well but had awe inspiring pedal pressure

My left leg was a mighty thing

The Saab one however prevented me from overthrowing the clutch which had happened two or three times on the older MMC inspired bracket and BMC clutch slave

That made it a worthwhile job for me, broken diaphragm fingers are just a tad annoying and as for pedal tramping, wow that was utterly horrid

Drawbacks with the Ford one included the very long bleed screw which stuck out for miles from the slave device

I ended up cutting a large hole in the top of the bell housing which also made attaching the hydraulic pipe easy too

Now I have a clucth bleed nipple I can easily access at the top of my bell housing, very easy to operate

So I discarded the remote bleed device I'd previously had on the car
bill l

Hi all, thanks for all the helpful suggestions. Im in the garage tonight but before I start I had a little measure of the Midget 1275 operating fork.

Mine measured 97mm from clevis pin to fulcrum and 70mm from fulcrum to centre line of release bearing.

I'll discount the pedal leverage as it is the same for both systems.

With a 3/4" master and 3/4" slave there is a 1:1 ratio. If you include the clutch fork you get 77:97 or 0.72:1 so the overall ratio is 0.72:1 or if the master pushrod moves 1" the release bearing moves 0.72"

With the SAAB 9000 concentric slave the ratio is Master piston area / Slave effective area or 0.6:0.426 or in round numbers 1.4:1 which means if the master pushrod moves 1" the release bearing moves 1.4"

So with the SAAB concentric you get twice as much throw for the same pedal movement.

That explains the overthrow problem AND the heavier pedal.

So to get back to the proper throw I need to either restrict master pushrod movement to half what it was and put up with a heavy pedal OR reduce the pedal leverage to half what it was and have the same pedal throw with a lighter pedal as a bonus.

Anyone care to check my figures in case I've got them ass about mammary?

Rob
Rob aka MG Moneypit

Hi Rob,

Maybe you could work out the ratio for the Ford concentric!

You can reduce the overthrow by fitting a shorter push rod or restricting the movement of the pedal (a wood block will work). You need to change the Master size to get a softer pedal. I think the clutch pedals all have the same leverage with only the 1500 brake pedal having more, rather than less leverage.

Preventing the overthrow and hoping the diaphragm has recovered will work and your left leg will soon get used to the heavy pedal.
Daniel Stapleton

If you measure the ID of the outer part and the OD of the inner part you can work out the effective are. Which is area of the biggest circle minus area of the smallest circle.

As regards the pedal. If the current hole (for the clevis pin) is Xmm from the fulcrum then if I drill another hole that is X/2 mm from the fulcrum all should be well. Provided the pushrod attachment doesnt foul on anything. It's worth a go don't you think!!!!!!

Rob
Rob aka MG Moneypit

Well I've nearly done it. Took the pedal off and drilled the same size hole half way to the pivot point. You have to crank the pushrod as close to the threaded part as you can to ensure the pushrod is in line with the piston.

There are a couple of other things I still have to do.

I'm doing it to the early pedal assembly. It would be a lot simpler on the later pedal assembly with the separate master cylinders.

On the early one you have to widen the hole that the top of the pedal pokes through to let the fork of the pushrod move lower.

The problem with a cranked pushrod is it won't be adjustable any more except if you take it off and rotate the forked end through 360 degrees to shorten or lengthen by 1 turn.

I've run out of time tonight so will continue tomorrow and include pictures if possible.

Rob
Rob aka MG Moneypit

Hi all. Well I've done the pedal mod and even with my basic tools it took me about 4 hours in total.

Now, I'd better say the clutch slip has improved but not gone away. That means I have two possibilities, both of which mean I take the engine out again. Really looking forward to that, not.

So, either the slave is reluctant to retract due to some fault (it was brand new but cheap so may be a copy), or I have damaged the diaphragm spring with all the excessive overthrow.

So onto the pedal mods. Let me say that this mod has transformed the feel of the clutch and made it so much more comfortable to use. Pedal pressure is now slightly lighter than the standard clutch, almost on a par with modern cars.

The first image shows the mods I did to the pedal and pushrod. The new hole in the pedal is almost half way between the old one and the pivot.

The pushrod was cranked as shown to keep the bit that goes into the cylinder in line with the piston while the forked end picks up the lower hole. The bottom arrow shows the forked end was shaped as shown due to it now pointing slightly down to pick up the new hole. The top arrow shows where to do a little bit of grinding so that the pushrod can be removed without removing the pedals. I also did this to the brake pushrod as it makes removing pushrods so much easier.

To be continued....

Rob




Rob aka MG Moneypit

The second image shows mods to the pedal box. The hole that the top of the clutch pedal pokes through needs to be widened so that the forked end of the pushrod can pass through with room to spare.
The forked end only just needs this space when it is fitted to the pedal using the new hole.

To be continued....

Rob



Rob aka MG Moneypit

The third image shows the end result.

This simple mod reduces the throw by about a half and due to the better leverage also reduces the pedal effort by the same amount.

This is what I had to do because I used a SAAB 9000 concentric slave. It may be different if you use a different one, it all depends on the effective area of the concentric slave you use.

If you do this mod to the later pedal box it will be so much easier. In fact you only need to drill a new hole in the clutch pedal and crank the pushrod.

Rob




Rob aka MG Moneypit

Sounds like you should get a complete spare clutch cover, plate, and release bearing for future use.

Otherwise if you can't get the exact same thing in the future, you'll have to make more alterations to make it all work again.
Lawrence Slater

Hi All, Like Lawrence I have been taking the engine out in the beautiful spring weather to see if I can find the slipping clutch problem.

I had narrowed it down to either the SAAB concentric slave or the Clutch diaphragm.

I firdt investigated the slave. I took it out to see how much effort it would take to force it to retract. I could do it by hand quite easily. Just finger and thumb pressure using both hands was enough to retract it fully so I'm of the opinion it isn't the slave at fault.

I took the opportunity of buying a new clutch outer from Moss on Friday afternoon so I could compare it with the one already fitted.

On the new one I put a straight edge across the face (see image) and used some drills to measure the distance between the face and the driven plate. I could get a 1/8" (8/64") diameter drill under the straight edge but not a 9/64" diameter drill.

I did the same on the original clutch and found I could easily get a 5/32" (10/64") diameter drill under the straight edge but not an 11/64" diameter drill.

Is this significant? Is it likely such a small difference could cause my clutch slip problem?

Rob




Rob aka MG Moneypit

Rob. Solved it yet?

This is interesting regarding clamping force.
http://www.apracing.com/Info.aspx?InfoID=127&ProductID=3081

Installation & Technical Information

The information contained in this section covers the relevant technical and installation details for the range of cover assemblies. This information includes:

- Mounting Holes:
- Dowel Holes:
- Mounting Hole / Dowel Hole Position:
-Set-Up Height:
- Diaphragm Spring:
- Release Plate:
- Clamp Load:
- Driven Plate Thickness:
- Torque Capacity:
- Maximum Rotational Speed:
- Maximum Release Travel:
- Release Bearing Type:

It is important that the correct type of release bearing is used for each cover assembly configuration. If a release plate is fitted a carbon thrust bearing should be used. If a release plate is not fitted and the diaphragm spring has straight fingers then a round nose ball type bearing should be used. If a release plate is not fitted and the diaphragm spring has curved fingers then a flat faced ball type bearing should be used.
The maximum recommended travel for the release bearing to prevent the diaphragm spring being over stroked. The maximum recommended rotational speed for each cover assembly. Given in rpm. The torque capacity for the clutch will vary depending upon which type of driven plate is to be used. The table gives the figure for all the various types of plate that can be run with the particular cover assembly. Given in Lbs / Ft and NM. Two thicknesses are given, the ‘new clamped’ thickness and the ‘minimum worn’ thickness. ‘New clamped’ is the thickness of the driven plate when first installed but with the plate in the clamped position. The ‘minimum worn’ figure is derived from the clamp load characteristics of each individual cover assembly, and can be used as a guide to the life of the driven plate. Whilst the driven plate thickness is between these two figures the clamp load stated will be within specification. When the thickness of the driven plate drops below the minimum worn figure the clamp load will be reduced which may result in clutch ‘slip’. The amount of clamping force exerted by the diaphragm spring (identified by colour on spring fingers). Given in Lbs and Nm Informs you if a release plate is fitted to the diaphragm spring fingers.The colour identifies the spring strength whilst the ‘design’ details the finger form, straight or curved (curly).The dimension from the flywheel face to the diaphragm spring fingers or to the top face of a release plate if fitted.
The angular dimension between any given mounting hole and a dowel hole, provided that they are both equi-spaced on their relevant P.C.D.Number of, diameter, pitch circle diameter and spacing.
Number of, diameter, pitch circle diameter and spacing.
Lawrence Slater

Not solved yet, everything out on the garage floor.

I've bought a Borg & Beck branded SAAB 9000 concentric slave in case the one I got cheap off eBay last year was not to spec. The new one I noticed was covered with lots of silicone grease, the old one had none when I took it apart to look at the seals.

The old one also had what looked like debris inside the hydraulic chamber and a number of scratches on the moving parts as well as an area on the moving piston (although outside any sealed area) that looked like a manufacturing fault. A bit like chatter marks you get when turning down metal at the wrong speed on a lathe. It maybe nothing except an indication it was a cheap make.

I had an interesting read of the AP racing website especially regarding the shape of the diaphragm fingers and the corresponding profile of the release bearing. The release bearing on the SAAB 9000 is flat but rolls of at the edge with about a 5mm radius. Any idea what the profile on the Burton release bearing looks like.

I also bought an early Mondeo concentric slave for the 5 speed inline setup. The picture looked like it would be an easy fit if I had to ditch the SAAB. What arrived was nothing like the picture. They supplied the later type with the cast in extension and when I complained they said "...don't worry it will fit in the same way....". Like bo**ocks it will, so I've sent it back for a refund.

I also sent off for a custom made hydraulic hose (company called HEL) to go straight from the master to slave cylinder. I specified 3/8 24TPI unf swivel male on one end and an M12 x 1.00 swivel male with a 45 degree bend on the other end. What arrived was the 3/8 end was ok but the other end was an M12 banjo connector. I rang them up and they said "we find this is the best way to do the M12 connection". WTF, is this a custom hose or what? I deliberately didn't want a banjo (it was available as a choice) so why the HEL
did they re-interpret my order? So I've sent that back requesting the correct ends.

So, on the whole not a very good week, and not much progress.

Rob
Rob aka MG Moneypit

Hi Rob.
You said. "The release bearing on the SAAB 9000 is flat but rolls of at the edge with about a 5mm radius. Any idea what the profile on the Burton release bearing looks like."

Yes indeed. I thought you'd find that interesting. I did too. It's the same as that. In fact it is the SAME bearing. SKF445248. Yup. SAAB.

Now it's also funny you should mention the shape, as I've been looking into that very thing. Again I figured you'd find that AP link interesting too.

Curly fingers flat bearing face, vs flat fingers rounded bearing face. And, thrust pad clutch cover, carbon bearing. WHY?

When the bearing is pushed forwards, the fingers are moved inwards away from the bearing. If both surfaces were flat you'd get square edges in contact with eachother. So one surface gets rounded off to begin with. And I suppose with the greater area of the thrust pad, a softer carbon is ideal -- except for modern traffic conditions, where there is far more clutch work, and it's better to have a roller that lasts longer.

PRELOAD.
You need preload on the release bearing. Not enough to cause the clutch to partially dissengage/slip, but enough to stop the fingers and bearing faces from wearing eachother out, each time they are brought together. The bearing has inertia. If there's a gap between the bearing and the fingers, each time the pedal is pressed, the bearing face is brought into contact with the fingers, and has to begin to rotate. Initially it would be static, and wear would occur until it was rotating, just like the tyres on landing a plane, and there might well be an audible squeal too.

So you hold the bearing in constant contact with the fingers. Too little force, and the bearing won't rotate, and both surfaces will wear, and it will squeal all the time, until the clutch pedal is pressed. Too much force and you know the result.

But I don't quite get why a carbon pad is in constant light contact. Maybe because the sudden contact from a gap, is simply to much mechanical stress, and it's better to have a continous light contact, even though that does wear the carbon a little.

Me not much progress getting the RWA midget back on the road either. I'm now bogged down investigating
DIY conversion methods to roller release.
Lawrence Slater

PS.
I'm wondering if a FLAT roller bearing face, against the FLAT metal thrust pad on a standard 1275/1098 clutch cover will work?

I'm about to try that out.

Meanwhile, if your slave was binding, that could well have been the cause of your slipping.
Lawrence Slater

Re preload. While I had the Mondeo slave in my hands I noticed they have a big spring behind the release bearing. This must be Fords way of providing preload, but that implies when the clutch pedal is released the piston pulls back slightly and they need the spring to provide preload.

Maybe SAAB chose to make the piston stickier so it doesn't pull back?

Rob
Rob aka MG Moneypit

As well as my Midget engine being out, my Sprite engine is out too, so I can see the inside of my T9 bellhousing.

I've just been down to my garage to confirm what I thought.

The Burton(titan) concentric, DOESN'T have a spring to keep the bearing pre-loaded.

Now that's interesting, because, my bearing had started to squeal, and is worn on it's face. The squealing goes away when the clutch pedal is pressed.

I've got the cover off my pedal box. Pushing the rod into the clutch master(effectively pressing the clutch pedal), forces the slave release bearing carrier out of the cylinder. As I let the master rod out, the slave carrier retreats ever so slightly from where it was when I stopped effectively pushing the clutch pedal.

I wonder if it's supposed to stay where it is?

Guy used a Ford concentric. And I recall him saying that his bellows type, has a spring holding his bearing lightly against the clutch fingers.

Lawrence Slater

Rob, you might like these clutch diagnostic pdfs.
http://tinyurl.com/kgbkjxw DiagnosticGuide04DL.pdf

And this one too.
http://tinyurl.com/l436pl6 Clutch System Failures.pdf
Lawrence Slater

The curved face release bearings I've used for flat fingers are like this http://www.ebay.co.uk/itm/Ford-Escort-New-Clutch-Release-Bearing-CB2113C-/280885711837.

I have used a flat faced release bearing against the carbon thrust plate but it was a Ford 4 speed box so the release bearing had the guide tube to keep it central.
David Billington

Thanks David, that confirms my intention to leave the thrust plate on the cover.

" --- so the release bearing had the guide tube to keep it central."

That's a good point. But would a roller be any more likely to run off centre than the carbon, and any more affected than a carbon if it does?

I guess I'll find out soon enough.
Lawrence Slater

I found this as an alternative to the Burton setup. It's for an Escort engine but should work with a Midget, just got to get the spacing right. Also, the images show a flat faced release bearing even though the Escort has flat fingers on the diaphragm.

http://www.rwdmotorsport.com/type-9-and-rocket-hydraulic-release-bearing-kit.html

Rob
Rob aka MG Moneypit

That's what Guy used I think, and it cost a lot less than that.
Lawrence Slater

Check this out Rob.

You can buy a complete clutch kit, and the concentric slave for £63.49 free post.

it's the wrong plate, but for the price you get a free slave cylinder that looks like Guys and the one you just listed.

http://tinyurl.com/m7jraan
Lawrence Slater

It's not the same slave as the rwd motorsport. If you look at the second image at rwd you can see it's got two ports side by side. The one in the clutch kit has ports opposite each other.

However, after much searching I came across this
http://www.ebay.co.uk/itm/130799844342?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

which looks identical to the rwd motorsport and also the burton one.

I've emailed the seller asking if the image shows the item being sold. It may seem like a silly question but I've just returned one I bought from eBay that used a similar picture but when it arrived it was the later FWD one. The seller claimed it would fit, which I expect it would have if I was fitting it to a Mondeo!!!!! Not a type 9 from a Sierra.

If the seller confirms it is the one shown in the image I will order it and try to fit in place of the SAAB 9000.

Rob
Rob aka MG Moneypit

I think with the right adapter plate, you could fit a variety of concentric slaves.

Like this one from a vauxhall maybe.
http://www.ebay.co.uk/itm/VAUXHALL-RELEASE-BEARING-CONCENTRIC-CLUTCH-SLAVE-CYLINDER-F13-F17-GEARBOX-/131427859599?pt=LH_DefaultDomain_3&hash=item1e99b5fc8f

Note the spring to provide preload.

But the one you've found looks good, esp for the price.
Lawrence Slater

Hi Rob,

Picking up on the comment you just made on the "Concentric Slave Cylinders. Preload or not preload" thread.

" ---if the clutch return pressure is less than the SAAB concentric was designed for, it could leave enough pressure on the fingers to cause the clutch to slip.
I'm pretty sure this is the situation I am in."

How sure are you, that you had a gap between the bearing face, and the clutch cover fingers, to begin with? I mean, was there any slack in the system?

This is what I was told today, on how to set up a CSC that doesn't have sprung preload on the bearing.

1). Bolt the clutch cover to the flywheel, WITHOUT the centre friction plate. Doing this will ensure that the fingers are as far back into the bellhousing, as they will ever get when the friction plate wears out.

2). Mount the bearing onto the carrier/piston, and push the piston as far back into the CSC as it will go.

3). Fit the CSC to the front of the gearbox, and use spacers sufficient to leave a "1mm gap", between the clutch cover fingers, and the release bearing face.

4). Replace the centre friction plate. This will depress the fingers, and the gap between the bearing face and the fingers will then increase -- by a set amount, subject to the gearing ratio that the fingers dissengage the pressure plate when the fingers are pressed in. With a NEW friction plate, you should end up with circa a 4/5mm gap between the clutch cover fingers and the face of the bearing.

5). Press the clutch pedal (activate the hydraulics). The piston will move forwards to take up the 4/5mm slack, before depressing the fingers. Then when the pedal is relaxed, the piston will retreat by a very small amount, and probably be pushed back slightly by any uneven running in the fingers relative to the bearing face.

From then on, as the clutch centre plate wears out, there is 4/5mm play in the system. And when the centre plate is fully worn, there will still be 1mm of slack, before the piston is fully retracted into the CSC, and can't go back anymore.


Lawrence Slater

Ah. Re-read the thread. You say you had an 8mm gap between the bearing face and the fingers, as built.

So if there's 8mm clear space behind the piston, there are only 2 possible causes.

1). The fluid, and hence the fingers remains under pressure. You said you opened the bleed nipple and now't came out, so that seems to be elliminated.

2). The pressure plate isn't exerting sufficient pressure on the friction plate.

What clutch cover are you using? What is the UNWORN thickness of the driven (friction) plate that MATCHES that cover?

What is the thickness of the driven (friction) plate that you are ACTUALLY using?

If it's too thin, specifically, thinner or as thin as, the "‘minimum worn’ thickness" of the correct friction plate that matches the clutch cover, then the clutch will slip.
Lawrence Slater

I'm using a standard 1275 clutch cover minus the bearing pad. The friction plate is a David manners hybrid. It's thickness is a shade over 8mm (I think). Anyway I compared it with a standard friction plate and it was the same.

Rob
Rob aka MG Moneypit

Then I'm all out of ideas. :(.

Something wrong with the friction material?
Lawrence Slater

I'm convinced it's an incompatability between slave and diaphragm. I think the slave itself requires a fair pressure to push it back far enough to clamp the friction plate properly. If the diaphragm spring is not strong enough to do this the clutch will slip.

So I think my choices are 1/ replace the SAAB csc with a Ford one (which is my next move, I just ordered one off eBay). Or 2/ Replace the clutch cover with something else with a stronger diaphragm spring. Something like an an Escort cover?

Rob
Rob aka MG Moneypit

Is the Escort a 6.5 inch clutch?
Lawrence Slater

Lawrence,

IIRC the only Escort with a 6.5" clutch was the early mk1 Escort and I used that driven plate with the 1275 clutch cover when I fitted the Ford 4 speed box in my sprite.

Rob,

I can't think of any reason why the clutch cylinder would need such force to push it back so maybe you have a faulty unit. As you're removing it then maybe dismantling it is in order to see if there is a fault.
David Billington

Following this thread out of interest as I may one day do a type 9 conversion.

With all the different CSC being discussed (SAAB/ various Ford units) - do they all have the same displacement that 'just happens' to work with the 1275 master cylinder diameter ?

Is there not a need to have a certain displaced volume from the master to achieve only the correct slave movement - over / under and it won't operate correctly.

The early cars had different diameter masters so do they require different CSC's ?

R.
richard boobier

May not help but looking for information earlier on Lawrence's Titan I came across the AP page here https://www.apracing.com/products/race_car/slave_cylinders/push_type_slave_cylinders.aspx which has a couple of cylinders and both come in 18mm and 12mm stroke options. I don't know if that is the maximum total stroke or intended design stroke to release the clutch but a Titan cylinder on ebay mentioned 22mm as maximum safe travel for that product.
David Billington

Richard. CSC's have an effective area which is sometimes quoted. The AP website says their SAAB 9000 compatible CSC has an effective area of 920 mm sq. However, I measured my SAAB 9000 and got 520 mm sq.
The 1275 slave is 1" bore which gives an area of 625 mm sq so they are in the same ball park. But there is the leverage of the clutch fork to be taken into consideration as well as where the pressure is applied to the diaphragm fingers.

With a standard 1275 clutch with the bearing pad the pressure is applied at the ends of the fingers. With a CSC you have to take off the pressure pad and because the CSC's release bearing is a bigger diameter the pressure is applied part way down the fingers.

As you can see it can get complicated if you think too much about it. Suffice to say they usually work, except in my case!!!!!!!!!!!!!

David. Yes I've crawled all over the AP website looking for clues. Found loads but not cured my problem.

Ah, well, tomorrow is another day!!!

Rob

Rob aka MG Moneypit

Well, after contributing? to a couple of other similar threads I have decided to do the following.

I have a new SAAB 9000 CSC which I will install. I also found in my box of bits a genuine Borg & Beck clutch cover with a loose bearing pad. A PO must have got pretty tired of the rattling between gear changes.

I'll remove the pad completely and use this cover.

Bolt it all together, install engine and gearbox and hope it cures the problem.

If that doesn't work I'll have to change over to either the Burton or RWD Motorsport setups.

In hindsight, it would have been cheaper (and certainly quicker) to tread where others have been before. Ah well, such is life.

Rob
Rob aka MG Moneypit

Richard
<<Is there not a need to have a certain displaced volume from the master to achieve only the correct slave movement - over / under and it won't operate correctly>>

Yes this must be true. When I was setting mine up I tried to establish the displacement needed but at the time I couldn't find any helpful data on the Ford concentric. I went to some trouble to rig up and bleed a remote clutch system between the car and the engine /gearbox sitting on the garage floor. I was then able to measure actual movement at the clutch. I was surprised to find that it was exactly right! I wasn't sure if this was coincidence or something to do with an industry standard. Or maybe some quirk of the physics of what is a comfortable travel for the human leg operating a pedal! I was lucky, but since it worked, that was good enough for me!
Guy W

It's a bit beyond my brain at this time of the morning, but it must be quite easy to work it out.

The fluid doesn't compress(assuming no air in it). So it can be thought of as a straight rod.

So knowing(calculating) the volume of fluid in front of the piston in the M/cylinder, and knowing the internal volume of the length of pipe from it, to the slave. And knowing the volume that the slave holds too. It shouldn't be too hard for one of the clever bod's here to work out how far the fluid in front of the piston in the M/cylinder, will push the slave piston.
Lawrence Slater

You don't need the pipe volume - this is the equivalent of the "solid rod" that you refer to and simply transfers the movement. Its only to do with the volume shifted by the m/c for one pedal stroke. Dividing this volume by the cross sectional area of the slave will give you the distance moved by the slave.

The complication for me was discovering what that cross section was for the Ford item. One needs both the internal and the external diameters of the fluid chamber, which I couldn't find at the time.
Guy W

Even 'easier' then Guy. ;).
Lawrence Slater

The CSC's on the AP website specify the "effective area" of the ones they sell. I'm not sure how they compare with the mainstream manufacturers.

The one they have which is compatible with the SAAB 9000 they say has an effective area of 920 mm sq. The SAAB 9000 I have I took apart and measured the two diameters and came up with 520 mm sq. Not sure why there is so much difference.

It gets very complicated working out pedal movement and clutch throw. In the standard system you need to know the pedal ratio, the MC area, the Slave area, the fork ratio and the length of finger (assuming it pushes at the end of the finger).

With a CSC you need the pedal ratio, the MC area, the Slave effective area, and where on the finger the pressure is applied.

Rob
Rob aka MG Moneypit

Rob,

perhaps you've mistyped, but you say,

"I'm convinced it's an incompatability between slave and diaphragm. I think the slave itself requires a fair pressure to push it back far enough to clamp the friction plate properly. If the diaphragm spring is not strong enough to do this the clutch will slip."

I don't understand that at all. Surely you're not saying the slave cylinder has so much friction that the diaphragm can't return it? The diaphragm springs are darn strong as it they that clamp the friction plate. Anyway, you had 8mm clearance when the system was empty and it still was slipping when the fluid was filled. What about the master cylinder, is that returning correctly? And is the return valve in the master clean? Did you rule out the 'going over-centre' and bending the diaphragm fingers?

Nick Nakorn

OK, this is connected with the CSC preload thread. The CSC release bearing needs to be in constant contact with the fingers. Ford do this with a spring which pushes the release bearing forward. The force imparted by the spring is insufficient to slip the clutch.

On the SAAB CSC there is no spring, so how do they ensure the release bearing is in contact with the fingers? I'm sumising that one way would be to make the CSC stiff to push back, but that would take carefull design. The CSC must resist push back enough to keep constant contact but not so much as to let the clutch slip. So, what if SAAB designed that CSC to go with the SAAB clutch. The SAAB clutch I guess would be bigger and stiffer than the 1275 clutch so the SAAB CSC/Clutch combo is designed with a certain stiffness but not enough to cause clutch slip.

If I pair a SAAB CSC with a 1275 clutch does this mean the clutch doesn't have enough push back hence causeing it to slip.

Just a theory.

Rob
Rob aka MG Moneypit

Missed the edit window.

I don't think the problem is the master cylinder. It is the same one I had in when I had the standard gearbox fitted to this engine in the same car. There was definately no slip then.

I don't think it's the return valve either. I've shortened the push rod and it didn't make much difference. If it was the return valve it should leave the system partially pressurised but if I release the bleed nipple nothing squirts out.

Overthrow is a possibility so I modified the pedal by drilling a new hole closer to the pedal pivot to reduce the MC movement and hence the Slave throw. It made very little difference.

I checked the pedal pivot for binding, there was none.

I checked the fingers by comparing with a new clutch I bought from Moss. They look identical.

I haven't found a way of comparing how strong each clutch is, just in case the original was faulty. The two clutches seem to be as strong as each other, at least when I stand with one heel on the fingers they both apear to be the same stiffness.

So I'm left with CSC faulty, clutch faulty or both faulty or in some way incompatible.

So I've got a new CSC to try and found an old Borg & Beck clutch cover just in case it is stronger than the modern ones.

That is tomorrows task. I'll be back....

Rob



Rob aka MG Moneypit

Hi Rob.

Here's a mad idea. But it will prove one way or the other if the slave is the culprit.

Put the clutch cover/plate back on the engine. But *DON'T* put the slave cylinder in, or at least not the bearing. Leave the fluid out so you don't spill it.

Or just recess the slave piston as far as it will go, and don't press the clutch pedal at all, so the bearing stays well away from the fingers.

Put the engine back in.

Have the car towed to a quiet stretch of road. Start the engine in neutral.

Have someone push you, and then matching the revs to the speed, go through the gears. See if the clutch slips.

If it slips, it's the clutch.

If it doesn't slip, it's the slave.

Lawrence Slater

Rob, it takes very considerable pressure on the clutch fingers to induce any slip. The ford spring is just a fine 1mm wire and very light to maintain the contact. I suspect it would work much the same with no wire at all. And l doubt the SAAB one needs any carefully designed stiffness in its operation to work as it should. The clutch fingers are way more powerful by comparison and will push the CSC to release properly. I don't think that is where your problem lies unless something is physically preventing the CSC piston from moving back far enough.

You have checked the obvious possibilities - pedal, push rod lengths. How about the clutch line? Is there a rubber hose flexible section. As with brakes, these can deteriorate internally and act as a one way valve.

Another possibility is that the CSC is mounted too far forward for your combination of flywheel/ clutch and bell housing with too many spacers. Did you take any check measurements when you put it together?
Guy W

Bloody hell guys I thought this was a well trodden path and a conversion that has been well worked out.



Anyone thinking of doing this conversion and reading all this will be wondering if it's worth the aggro?



Thank god the 1500's can take an overdrive using all standard bolt on bolt on parts!
SR Smith 1

Guy, the hydraulic pipes are copper with a custom made flexi. If there was any possibility that the flexi was working as a one way valve it would leave residual pressure in the system which would have resulted in a squirt of fluid when I opened the bleed valve. The bleed valve is on a 6" length of copper pipe and it is not kinked. There was no release of fluid when I loosened the bleed valve.

It can't be the CSC too far forward. When I installed it with the CSC in it's fully back state there was a gap between the fingers and release bearing more than sufficient to allow for clutch plate wear.

I think I should have taken the well trodden path with this conversion rather than making do with bits and pieces collected over the years. It may well have been cheaper in the long run and would certainly been less agro and on the road sooner.

If when I install the new SAAB CSC and Borg&Beck clutch cover it still doesn't work I may have to re-consider my options.

Rob
Rob aka MG Moneypit

Just suggestions,Rob. Sounds like you have eliminated those ideas though!

Are you able to view what's going on inside through the vacant bell housing opening?
Guy W

As I've mentioned before Rob the SAAB roller bearing comes with a spring and a rubber(?) bellows to protect its working bits

They sit on the CSC nose and are 'supposed' to clip together when the roller clicks onto the CSC nose

The sprung bellows provides close in action for the clutch just like the Ford one, but with a slightly stronger spring

I have just reread the thread but I haven''t seen anywhere that you report inspecting the diaphragm Rob

In the dark days of yore before I got the right balance between CSC and pedal I broke two (or was it three) diaphragms due to overthrow and the pedal tramping that went on

I wonder if that is what happened to yours?

I found the diaphragm plate on each one had a radial crack across it, that stopped the clutch applying pressure to the clutch plate

I just wonder...
bill l

Hi Bill, the SAAB 9000 I bought doesn't have a bellows, or it wasn't supplied with one at any case.

http://www.ebay.co.uk/itm/301389043954?_trksid=p2057872.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT

I can't see any damage on the diaphragm and it seems as stiff as a new one I bought to compare it with.

In case it's the CSC I bought a new one (see above link). In case it's the clutch cover I found an old Borg & Beck to use. I'm in the middle of putting it back together but probably won't do much until next weekend.

Rob
Rob aka MG Moneypit

To be fair Rob I am not sure whether it came with the slave or the bearing but there was one with mine

I did buy the bearing from a different supplier to the CSC though, for nothing else but financial reasons

Buying the bearing from the CSC supplier was more expensive

And I am a cheap git who learned cheap gittishness from a Nexpert
bill l

I was born cheap. lol.
Lawrence Slater

Born cheap?

you was lucky

When I
bill l

:) bill.

Come on Rob. We can't be expected to wait until the weekend for the next installment. Can't you go into the garage tonight and do a bit more? ;).

Otherwise, we'll need some thread drift to tide us over. Any takers?
Lawrence Slater

Any news Rob?
Lawrence Slater

Hi Lawrence et al, not much got done at the weekend. It was a family gathering on Saturday and didn't feel very well on Sunday (the two events are not related!!).
I got as far as installing the B&B clutch, SAAB CSC and joining engine to gearbox.

One thing I noticed about the B&B clutch is the fingers are longer than the Moss supplied one. A goo 2mm longer so without the pad the hole made by the finger ends was 4 mm smaller. Luckily, just enough to clear the guide tube on the CSC when the clutch is near the end of it's life.

I took a close-up to show clearance. Between finger and guide tube is about 5mm. I could just about squeeze a 5mm screwdriver blade between the two. The CSC is in it's fully retracted position about 3mm from the end of the guide tube.

When I get time at the weekend I will connect up to the hydraulic system to see what happens.

As a contingency plan I have purchased a 7.5 inch clutch cover, Quinten Hazel number Q10007, and I am getting a spare flywheel modded to accept the larger clutch cover. I has curly fingers and should be ideal for the Ford CSC I bought a week or so ago. Good old eBay, the Ford CSC was £28 and the clutch cover £14 with free post on both. I wish I had done more research before going the SAAB CSC route 'cause they are £68 just for the CSC!!!!

Rob


Rob aka MG Moneypit

Breath bated for next update then Rob. ;).

"Between finger and guide tube is about 5mm" A miss is as good as a mile. :).

You're right about the relative costs of the CSCs. I guess the first conversions were probably SAAB csc, and most just followed that. I can only assume that the Titan(Burton) csc SAAB version, is considered superior for racing, since Titan are a race outlet, and the Titan seems to be sold by those modifying for race.

But otherwise, what's the difference? The all do the same job, but as you say, some are a whole more expensive, esp when you add in the mount and the spacers.

Mine, Titan(Burton), came as a kit 15+ years ago, and wasn't that expensive back then, but if I have to replace the csc at anytime, I'll go for one of the myriad cheaper ones out there. The Titan csc alone is now £99.41 inc vat, but plus delivery. Although since I already have the mount and spacers, it's probably easier to stick to the Titan.
Lawrence Slater

Hi all. Hope you haven't been holding your collective breath for this update.

Well after a new CSC has been fitted mated to a used but genuine Borg & Beck clutch cover I think it is now ok. I'm keeping my fingers crossed but I took it out for the first time today and can't feel any clutch slip. I even accelerated up an incline in fifth without any signs of slip, but the engine was a long way off max torque, but then again last time it slipped very easily.

So not sure what the real problem was.

Besides the CSC and clutch cover I did a number of other things whilst the engine was out. I fitted a custom made flexi (HEL Automotive) that has a larger internal diameter than the copper pipe I previously used. Maybe this had some bearing on the ease with which the pressure plate could push the CSC back?

I also noticed the flywheel where the plate rubs was very glazed so I rubbed it down with 600 wet and dry and thoroughly de-greased the whole flywheel. I did the same to the pressure plate.

I also noticed uneven wear marks on the driven plate when I took the engine and gearbox apart. I'm not sure whether the flywheel should have been skimmed or not or whether there are high spots in the material but I expect as I put mileage on the clutch it will wear into the flywheel and provide more grip so reducing the possibility that the slipping will reappear.

So, is this the end of the saga? I hope so!!!!!!!!!!!!!



Rob aka MG Moneypit

I thought I would add some info for the archives about some of the things I have done and learned.

One of the things I found is that to start with I experienced too much clutch throw. This can be cured in a number of ways. 1/ put a stop behind the clutch pedal between it and the bulkhead. This will stop you pressing too much on the pedal. 2/ Shorten the pushrod. This will mean there is more free play before the pushrod actually moves fluid. 3/ Move the pushrod pivot point closer to the pedal pivot point to reduce the throw. This is what I did. It was easy to do, taking an hour or two, and resulted in a lighter clutch action due to the greater leverage. I drilled another hole for the clevis pin almost half way between the old hole and the pedal pivot. The new hole is about 1mm closer to the old hole than the mid point. If I needed to do it again I would move it another 1mm closer (2mm closer to the old hole than the mid point). You need to bend the pushrod to ensure entry to the master cylinder is straight. You need to enlarge the rectangular hole to accomodate the full width of the wide end of the pushrod. I think there are pics in this thread somewhere.

Fluid leaks from the connections to the CSC were a problem. Knowing how tight to do up the unions was a problem. With the gearbox next to the car I could connect the long flexi to the master cylinder. I used a piece of square section pipe clamped across the bell housing. I drilled a 30mm hole in the centre of one side wall for the input shaft to poke into. With this in place and tubular spacers between it and the CSC release bearing I could get the OH to apply maximum pressure to the clutch pedal so I could check for leaks. I was surprised how tight I had to make the unions to ensure fluid tight joints.

The total throw on the SAAB 9000 CSC is 18mm. I checked if this was sufficient and how much safety margin I had before it popped. After connecting the gearbox to the engine I measured the distance between the end of the CSC guide tube and the clutch fingers. I used a flat bladed screwdriver to do this. I chose one whose width fitted in the gap and measured it. In my case it was 5mm.
I then slowly moved the release bearing till it touched the fingers and measured how much the CSC had moved. I did this using a long 1/4" extension with various size sockets on the end. One of them fitted snuggly and when measured it indicated a movement of 10mm. So I had to disengage the clutch in the remaining 8mm and still retain a safety margin. I got the OH to operate the clutch and checked the extra movement needed to do this. It was about 3mm so I had about 5mm margin left. This is all with a new clutch plate. As it wears it gets thinner and the fingers move away from the flywheel so the safety margin gets better.

The only other worry now is that as the clutch wears the fingers will reduce the 5mm gap between the fingers end and the CSC guide tube. The CSC guide tube is a larger diameter than the hole made by the fingers so I may reach a point where the fingers touch the CSC guide tube, but that is many thousands of miles away and will worry about it if oe when it happens.

Rob







Rob aka MG Moneypit

Sorted Rob and thanks for updating us
bill l

This thread was discussed between 21/02/2015 and 18/04/2015

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.