MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - the correct orientation of the clutch disc?

What is the correct way to install the clutch disc?
I'm going to be removing the trans today and just want a second opinion.
Thanks!



David Barrett

On a 1969 1275 Sprite
David Barrett

David,

I haven't changed a clutch for a few years but when I did the driven plates typically had some text stamped near the centre spline saying "flywheel side". When you look at the plate from the side the centre section within the friction lining is typically deeper on one side and it is the deeper side that goes away from the flywheel otherwise that section can foul the flywheel and cause problems.
David Billington

Thanks for the reply
I didn't notice any markings upon installation
I called Quantummechanics during the process to make sure I had it right
I just wanted to verify
David Barrett

David,

If you have a "Quantummechanics" clutch wouldn't that be like installing Schrodinger's cat into the bellhousing in that until observed you can't tell which way round the clutch is actually installed.
David Billington

Im not clear on what "Schrodinger's cat" is.
I dont even know if having the disc in backwards WOULD cause the slippage Im experiencing.
David Barrett

David good luck with the clutch check

One thing I would advise is very careful examination inside the diaphragm of the spring plate which is the major pressure applying part of the clutch cover unit

I found that I broke two covers/springs on my car before I finally got it all set up right

When the plate breaks one finds that what ought to be a dished ring of unbroken steel sheet cracks across to stop the diaphragm fingers applying true, direct pressure all around the clutch, thus allowing the clutch to slip

The driven plate the wrong way round (which can sometimes happen) is the least likely option on your car in my opinion, even though I suggested it as a posible cause of the trouble


A possibility I don't remember any of us suggesting is loose screws holding the clutch to the flywheel, I hope this is "all" the problem is.

If so, a dab of threadlocking adhesive to each one as you torque it down should be a quick inexpensive fix.

Again

good luck
Bill

David,

http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat

A reference to the concept that you can't tell which way round the clutch has been installed until it is observed, prior to that it could be in either state. Particularly pertinent to "Quantummechanics" products.
David Billington

Very good David although in fairness not too many would have any idea what on earth you were refering to.

In the past and from most clutches I have ever installed the driven plate can only be installed one way. If you fit it the wrong way round you will find that the springs will foul on the flywheel and the plate friction material will not sit down onto the flywheel surface. Try placing the fricion plate agains the flywheel and you will see what I mean when you ty it both ways
Bob (robert) Midget Turbo

Bob,

My apologies, but with a supplier name like "Quantummechanics" I couldn't resist a leg pull, I must have watched Horizon or similar too many times. I suspect though that the theory might extend to many classic car problems where quantum mechanical effects control the outcome of parts fitting such as rotor arms an condensers.
David Billington

It needs to be stated that "David Barrett", has installed a ford Type 9 transmission and "Quantum mechanics" is the name of the company here in the usa that sells the ford type 9 conversion kit.

So we need to hear from those that have installed the type 9 tranny conversion as they are the ones that will know which side of the disk faces the flywheel....

Im surprised that QM didnt state in there directions which way the clutch disk goes in ....It will make a differance, I know....

Im really looking forward to hearing what you come up with david, please keep us posted.


prop
Prop

brilliant, David B, I'm still with you, the concept of condensers and rotor arms bring in a state of both working and not working at the same time would explain a lot of past problems aired on this BBS....
David Smith

Pulled the motor and trans tonight. I cant see anything wrong with any of the components. It looks as though the pressure plate diaphragm fingers are sitting very flat...dont know if this is the way it should be. Ill try to attach pics...


David Barrett

And another...


David Barrett

any Pics as to how the disc was facing the flywheel, did you get a measurment as to the thickiness of the flywheel....to see if its been over re-surfaced


prop
Prop

David,

In the top right of the first picture you appear to be missing one of the 3 dowel pins that align the clutch cover. The picture doesn't show the others so can't see if they are missing also. Fingers appear about right for a new clutch IIRC.
David Billington

Those fingers do look very flat to me. I would expect them to to form a slight cone shape pointing rearwards in the middle. Maybe my clutch is a lot more worn though!

What gearbox are you using - that disc surely has too many splines on it for an A-series box?

My guess at this stage is that the plate is the wrong way around. It should be stamped "Flywheel" side, but if not then check the centre hub of the disc. The hub extends further out on one side than the other. The long side must point towards the flywheel. On yours it looks like the splined hub is extending to far outwards - I think it is in the wrong way around.

Guy
Guy Weller

Guy,

David Barrett has a type 9 conversion in his car supplied by the US supplier QuantumMechanics.
David Billington

Ah, that explains the 22 splined shaft!

But the issue about orientation of the plate still applies. I am pretty sure that the longer side of the central boss needs to point towards the flywhweel.
Guy Weller

I laid the long side against the flywheel after disassembly, and it seemed that the disc would interfere with the flywheel bolts. How can I tell if the pressure plate is defective?
David Barrett

David,
Sorry, I am going to back down on this one. If it were a standard clutch and driven plate for an A series gearbox, then the longer side of the splined centre hub would definitely point forwards towards the flywheel. But if you are using a different application then I am not so sure.

Are you certain that the driven plate doesn't have any markings to say which is the flywheel side?

Guy
Guy Weller

David,

Did you see my comment earlier about the apparent lack of at least one dowel pin. Does your flywheel have dowel pins fitted.
David Billington

I'm not much concerned about the spline orientation, I'm sure that David will have had the sense to fit the plate the right way around

but

I've seen a few clutch covers fitted to my engine now, for my type9 and what Guy says about the fingers makes sense

I wonder if David has been supplied a plate which isnt quite thick enough for that particular clutch cover

The cover seems a little deeper than I remember the last one being, which would have the effect of putting less pressure on the driven plate from the outset

maybe two maker's systems in operation together which wouldnt usually happen, thin driven plate - deep cover plate = low drive plate pressure

I think this is worth a little research, I'll check my old clutch comparison book which I used when attempting the BMW gearbox thing...

David remind me

have you had the flywheel redrilled to suit the larger diameter clutch or is this the six and a half incher?
Bill

I can see 'Leamington Spa' on the cover, so presumably it's a Borg & Beck casing. Agree about the flat fingers though. It's only two weeks since I put a new standard one in, and the cone was obvious. And since it was all A-Series, the driven plate was flat side to the flywheel (it wouldn't go the other way).
Nick

Nick,

I just looked at the fingers on the 6.5" clutch on my 1420cc A series and they look flat like David Barretts pic and it has done a few miles. IIRC it's a heavy duty variant.
David Billington

Its the 6.5" clutch.
The T9 disc is THINNER than the stock disc. Im wondering if that is supposed to be that way????
David Barrett

Also, I have not been able to get in contact with Quantum' about a solution to this problem.
David Barrett

David,

By how much is it thinner?. IIRC some clutches have the steel fingers connecting the inner section to the friction material deformed so sort of wavy when viewed from the side, I presume to provide a smoother take-up by requiring some compression before the driven plate is solid. It may be your stock disc is like this and the T9 plate not so or less so. If that is the case you may have to compress both discs to take a valid measurement. Clutch cover dowel pins?
David Billington

only 2 dowl pins
I'll measure the two discs tonight and get the numbers posted up. As well as some side by side pics of the oldand new.
Has anyone converted to a stock Merkur clutch in this application?
David Barrett

Im considering modifying the stock 1275 flywheel to accept the Merkur/ Sierra clutch.
Any thoughts???
David Barrett

I see that Nick contradicts my version of which way the driven plate goes on. And as I believe Nick to be accurate in what he says I thought I better check my own assertion. Looking at the facsimile copy of the original Workshop manual explains it all. The cross sectional clutch drawings show the flat side towards the flywheel just as Nick says. But for the MK IV sprite/ MK III midget it goes the other way around! Para 10 on page Ea.2 "long side of the hub towards the flywheel"

Second point - the thinner the driven plate the more cone-shaped the fingers will appear on that type of clutch cover. Opposite of what Bill seems to imply.
Guy Weller

David,

There are standard 7.5" T9 clutch assemblies in Europe that can be fitted to the flywheel and IIRC the cover is the same as many other 7.5" clutches in the same way as I fitted a 6.5" Ford Escort clutch in place of the 6.5" sprite clutch as a straight swap onto the 1275 flywheel when I fitted a Ford 4 speed box to my A series. The covers seem to be the same but the diaphragm springs differ as the their weight and ID/diaphragm finger details/carbon release face present or not depending on application. Do you know what the Merkur clutch size was ?. IIRC the issue with some 7.5" clutches is they may need slight machining of the OD to clear the starter Bendix when fitted to spridget flywheels as potentially slightly larger OD than the coil spring clutch used on earlier cars.

2 dowel pins, would that be 3 at 120 degrees with one missing or a 948 flywheel with 2 at 180 degrees.
David Billington

Turns out I was wrong about there being a difference in thickness between the new (T9) disc and the old disc. I mic'ed them and the difference is negligible.

Here are some pictures of the two discs:

The top one is the T9 disc




David Barrett

Heres the other side of the discs:


David Barrett

And heres a side shot of the discs.
As you can see the T9 disc doesn't have same wavy spring between the the two friction surfaces.


David Barrett

I managed to find a picture of the clutch I am using now just before I mated the box on its new concentric slave cylinder

I can just make out a slightly "more cone-ey" look to the fingers than seem to show on David's picture

Other pictures I have confirm the position of the spline centres to be the same as he fitted the plate too, so eliminates that as a possibility

David on my clutch cover the Leamington Spa and Borg and Beck also has impressed around the rim "type-6-6½ DS" on it does yours?

Mine now is the standard cover plate supplied by the Morris Minor Centre after I tired of trying to source a cover out of the system.

If yours doesnt have that around it that may be the reason for all this kerfuffle

Hope this helps a little

When I get my photobox pictures set up I intend to show every picture I took during the concentric development phase, in the hope it can help work these things out


Bill

In this shot the broken plate on the right and the new plate on the left can be compared

the minimal wear on the broken plate "upsets" me every time I see it

I dont think that one lasted two months


Bill

David,

Is it a trick of the light or does your t9 clutch disc appear to have a localised wear/glazed area.
David Billington

Pretty sure it a lighting issue.
David Barrett

Bill;
How did you determine the plate was "broken"?
David Barrett

Heres a picture of the flywheel.
Also, does anyone know what mods need to be made to the stock 1275 flywheel to accommodate a 7.25" clutch?


David Barrett

Hey david....

for having the flywheel re-surfaced only once during its life time, they certianly took ALOT off the face.....Id get it measured and compare it to what ever the allowable tolerances are....you certianly dont have much of a lip left on the contact surface....mine has been resurfaced 3 times and I easily got twice to 3 times as much metal left on my flywheel....I have to say thats where alot of your problem is IMHO...the flywheel is just to thin


also you can see where the disc is spinning on the flywheel....Add to the fact that you said if the disk is rubbing and fouling on the bolts whith the long side of the spline hub which should be correct certianly indicates that the flywheel is to thin...thus the reason you may have it installed back wards


it appears that you easily lost 1/4 of an inch minuimum, maybe even 3/8 of an inch or more....thats alot of metal...

Id have to say this may be part of the culpret for loosing and getting 1st gear jambed up in the rib case as the plate was probably getting hung up due to coming off the splines to much, causing a whobble stuck angle position on the input shaft/disk splines


If this is the cause...Id recommened an aluminium flywheel from fredinsa....if you look around you can get one for around $300 - $350....but they are a 1/3 the wight and the contact surfaces can be replaced instead of resurced....

prop
Prop

Prop,

Are you thinking of a 1500 clutch which I think has the flywheel friction face sunk towards the engine relative to the clutch cover mounting face. The 948, 1098, and 1275 spridget A series have the flywheel friction face and clutch mounting level so that whole surface can be skimmed easily as one without upsetting the clutch, you would have to take off considerable to foul the flywheel/crankshaft bolts. From Davids end on picture its not easy to tell how much has been taken off but it looks close to standard.
David Billington

Prop:
Are you telling me that the step in the flywheel should be @ 1/4" - 3/8"???
I cant imagine that it came [from the factory] with that much of a step.
Having said that, Ive never seen a brand-new flywheel before. So correct me if Im wrong.

Aside from that, I dont think that is the cause of the slippage. For one, it wasnt slipping with the rib case and this flywheel, and virtually the same pressure plate as well as a disc with the same thickness.
Also, no matter how thin you cut the flywheel, (within reason), as long as the proportions between the friction surface and the pressure plate mounting surface dont change, the clamping force the pressure plate applies will not change.
The only effect cutting a flywheel too thin can have is clutch fade caused from overheating the flywheel because not enough material is present to disapate the heat adequatly. And this is moslty experienced under harsh driving, somthing I never was even able to do because the clutch would slip anytime I gave it more than half throttle.
David Barrett

>>>>>>Are you telling me that the step in the flywheel should be @ 1/4" - 3/8"???<<<<<


Yes, Thats what Im saying!!!!....if you look close enough you can see where the step is almost blended into the rest of the flywheel and no step exist.


looking at the shaded area where the disk is slipping agianst the flywheel, indicate that the spline secting cant go any further and is riding agianst the sect of the flywheel where the 6 attaching Flywheel bolts are in the ressesed area and are not allowing the disk friction pads to make full contact...PLUS look at the disk spline hub face end...its incredably shinny ...agian indicating that is riding in that recessed area (AGAINST) the flywheel....thus meaning its to tall and the friction pads cant make full force contact...AKA the spline hub is the obstruction.....maybe grinding the face of the spine hub down will allow the pads (friction matreial) to fully set agianst the flywheel face that has been (OVER skimed)...even the area next to the piolet bushing shows something slieghtly rubbing agianst it....

but then agian maybe my laptop screen needs a good washing and I know Im in need of glasses. But thats what Im seeing in the photos....If what I am saying is not really there in the photos then I conceed that Im wrong.


prop
Prop

Prop,
If I understand you correctly, you are saying you think the center of the disc (the longer part with the springs and the splined hub) is riding against the center of the flywheel where the flywheel mounting bolts reside??

If that is what you are saying...

That cant be, because the way I had it installed, the "long" part of the disc was facing the pressure plate side NOT the flywheel side. The side that was facing the flywheel was virtually no deeper than the friction material part of the disc that rode against the flywheel, which left PLENTY of room between the disc and the flywheel.

Furthermore, I checked the disc and held it against the flywheel both ways and found that IF I had installed it backwards, then what you [Prop} are saying would be absolutely true. It WOULD interfere with the flywheel bolts and would NOT ride properly against the flywheel. But that is NOT how it was installed.

Also, I talked to John at Quantum today. He says he'll have an answer about this problem by the end of the week.

At this point Im seriously considering converting to a 7 1/4" clutch. I really wouldnt feel good about just installing another clutch just like this one WITHOUT having any solid answers as to why it was slipping so badly.

Any thoughts on that??




David Barrett

I have been thinking about that...

It seems your really bent on going to the up grade....not a bad thing, it would make it indistructable...plus sometimes when you get an itch...you just have to scratch it no matter what...read back in the arcives mmmm 16-20 months ago about me and my hurricane wheels adventures...lol


but it would certianly narrow things down, and being that you want to do it ...no time like the present while you have it all apart anyway


there are only 5 reasones I can think of why (on this set-up) the clutch is slipping...which it clearly is.



1. to much horse power comming out of the engine.

2. there was still a film of grease/oil on the flywheel/disc from being re-surfaced and this caused some glazing...a hard burnt shell that will not allow the disk to grabe hold of the flywheel

3. the disc is installed backwards,... its the wrong disc,.... or was manufactured incorrectly

4. there is some kind of obstruction between the flywheel and the disc thus not allowing the disc to fully set with all of it force agianst the fly wheel

5. for what ever reason the push rod on the slave cylinder is not fully disengaging the throw out bearing and causing the throw out bearing to ride agianst the pressure plate thus not allowing the clutch to be fully dis-engaged

I cant think of any thing else....there is nothing else outside of those 5 reasons for the clutch to be slipping on this type of set up.

So Id do the up-grade as your wanting, and take every miniscule overkill percaustion to avoid the 1st 3 reasons.....use a sander on the flywheel to sand off any glazing wash it with break cleaner, wear nitrate gloves, keep the new disc and flywheel free of any touch of anything, next photoghraph with scales and mark everything with highest detail...is the spline hub end shinny or not, any makings...I mean everything!!! that has to do with the clutch and flywheel...no matter how insigfiecent.


then assemble....If it works and no slippage ...congratulations.....(probably not IMHO), If it slips, then make it really slip...alot of slipage,,,really grind it in....then pull it apart compare everything to your absolite in deepth notes and photos.... if anything is differant no matter how small...then you have your answer....if on the other hand nothing is there and looks and measures exactly the same as when you installed it... then the whole problem is solved by the process of elimation ...#5...a problem with the push rod being to long...and thats another chapter in an of its self

I would make one suggestion measure the length of the bell housing and make sure its not to short thus forcing the throw out bearing into the clutch...I consider this a #5 issue but its easy to check at this point in the game....


beyound that there is nothing else I can think of...if there is, I cant wait for the others to speak up, cause Id love to hear it.

prop
Prop

My gut feeling is still related to the flywheel being over skimed...You just cant take 3/8 inch off and not have a problem somewhere...thats a #4 btw.

you have to admit of the 3 photos you submitted, the 1st photo with the face of the spine hub is really shinny and a little worn....there is also a grove going cross ways that is cut into all 5 springs and a bit of a shine on the thin edge of the sheet metal keepers that hold the spring....if Im not mistaken thats the side you have facing the flywheel.


If your going to go the upgrade, I would still highly recommened going the aluminum flywheel...its a 1/3 the wieght, so its going to spin up super fast, you will gain a bunch more horsepower, and you will increase the life of your high performace motor, cause it dosnt have to struggle with all the extra wieght.....and a big plus...you eliminate what I belive to be a real problem....the flywheel is over skimed...its to thin......

at the vary least if you dont go the aluminum flywheel at least get another flywheel with some meat still on it, off ebay...im guessing you can pick one up for under $75....that right there is worth the price of admission for taking that whole senerio out of play.

prop
Prop

BTW...You have to remember the amonunt of differance that we are talking about from this thing screaming down the road and slipping at the current level... is easily with-in .30th of an inch...thats three-hundredths of an inch


Im guessing that prediction solely on the photos and the past discriptions of the various drives.

prop
Prop

You forgot #6.... defective pressure plate.
Ive never had this happen before, but the more people I talk to about this problem the more that explanation keeps popping up.
Heres a picture of the flywheel on an angle.

Prop, as I said before, I just can't imagine the flywheel ever was 3/8" thicker than it is now. I wish someone would chime in with a picture of a stock piece so we could compare.


David Barrett

well its thicker then I thought but its still thin....like I said...my machine shop guessed my flywheel had been skimed about 3 times (including my once) and I easily got 3x more metal then you Have.....


Okay #6 is a broken pressure plate....granted, like you, I have never heard of that happening as well until this thread we are currently on....so is your pressure plate broken or cracked across the face.....(I didnt think so...LOL)....

prop
Prop

here's a standard 1275 flywheel. At the ring gear it is a tad over an inch thick, my 1" mic would JUST not fit. And the step for the friction surface is 3/32".
Mods to fit the larger clutches usually are re-drill and tap the mounting holes, rebalalnce the assembly, and relieve the inside of the bellhousing where the cover touches.


David Smith

Perhaps it is something to do with those cover plate "fingers" being too flat. Being flat, implies that the pressure plate itself is either being pushed rearwards by a nice thick driven plate - as it should be. Or that the pressure plate is being held rearwards and isn't nipping the pressure plate - which would cause the slipping.

Perhaps the clutch cover is faulty, sticking, or just too deep for the standard thickness of driven plate?

Guy
Guy Weller

David,

Have you compared the details of the diaphragm, such as thickness and position of the fulcrum points, on this clutch and the old one that worked with the ribcase. Have Quantum mentioned what sort of power/torque the supplied clutch is intended to handle.

I think Props 1/4" to 3/8" reference only applies to a 1500 flywheel.
David Billington

IMO David B's flywheel is perfectly OK except that when skimmed it had one of the dowels skimmed too

Ceratinly within acceptable limits to operate the car

David, to answer the question you asked the diaphragm inside the casing is a continuous disc which exerts pressure (downforce) onto the "pad area" of the cover plate under spring pressure

when it breaks the continuous ring of the pressure spring gets a crack right across it, radially. This then turns the ring into a "thing" like a split washer

On the photo of the cover plate you can see the slight variation between the distances the separate fingers lie apart, the gap in the spring being just where the gap is visible. Just around alittle from where the fingers change the plane they lie in

the plane changes because the spring plate can no longer exert the uniform pressure across the diaphragm

If you cant see that there has to be some other explanation for the problem, I wonder if the cover plate has a deeper dish than mine, which would reduce the pressure on the driven plate. That was why I told you the figures that Borg and Beck had pressed into the edge of it the sequence of numbers and letters has to have a meaning to the guys in the factory

When I bought my second plate (the one that lasted merely a few weeks) I noticed that the pressure pad, the ring that operates against the clutch plate is thinner than the one it replaced.

I am doing some searches for information on this as that may be a deciding factor

I'll let you know but for now, go check for the numbers and letters TYPE-6-6½ DS which is embossed in the successful cover plate I am using
Bill

And I'll tell you what!

I would NOT be very happy driving around in the car with so many of the tabs not engaged on the flywheel bolt centre washer.

Time to take a chisel or other suitable tool to lift and pinch those tabs

I've been searching my handy-at-the-minute National Clutch Components catalogue for compatible clutch covers. This means the part numbers I quote are from National Clutches and will need cross referencing with other makers parts.

Ford (Europe) have two 165 mm clutches listed
One of these (maybe the Fiesta957/1117cc version) has a cover that the bolt hole drillings are incompatible with the symmetrical hole fixing around the Spridget flywheel but the other has the same spacing as our cars

The cover numbers are:
NHE2032 which is the Fiesta version
NHE1011 which it lists for Escort Mk1 940/1100 cc

IMO the Escort Mk1 version is most likely to be Spridget compatible, this needs checking at your local friendly "Clutch Wizards" shop

There are also two driven plate numbers listed, again they are Fiesta and Escort but my handy book has let me down on spline numbering and diameters, further research is under way we need 23 splines

I need another copy of the online clutch catalogue I used to have, but I can't remember whether I found it at Sachs or B&B. Whichever it was it gave spline dimensions as well as the other useful data

When I gave up on the BMW 5-speeder I let the files get cleared out! "Whadda mistaka to mike!"

Any road up! The Clutch plate numbers listed are:
NHB2033 (Fiesta 957/1117cc 76-9/86)
NHB1030 (Escort 940/1100 Saloon 68-3/73 [mk 1])


More later I hope
Bill

Bill,

The escort clutch cover is the compatible one as I used one originally when I went to a Ford 4 speed box before reverting to the standard spridget 6.5" cover.
David Billington

Bill,

Also IIRC the hole in the centre of the diaphragm is smaller on the escort clutch cover than that shown on David Barretts 6.5" clutch cover for the t9 so it might foul the input shaft or release bearing guide sleeve.
David Billington

Bill, yes the letters:TYPE-6-6½ DS are stamped in the pressure plate.
David Barrett

Also, what is IIRC?
David Barrett

IIRC = if I recall correctly

Have you compared the details of the diaphragm, such as thickness and position of the fulcrum points, on this clutch and the old one that worked with the ribcase. Have Quantum mentioned what sort of power/torque the supplied clutch is intended to handle.
David Billington

I have compared them. Its difficult to make a direct comparison due to the fact that the throwout bearing is integrated into the old pressure plate, and the new one was removed and machined for the T9 trans.
Aside from that they look to be exactly the same.

John at Quantum said he has customers with this tranny swap that in race cars that make 125+HP without any slipping issues.
According to him, and the company he gets the clutches from, I am the first customer to have this issue....lucky me!
David Barrett

So you have good news and bad news

good
the proper clutch cover has been supplied, with the right markings the same as the one that is serving mee very well at present
the clutch driven plate WAS orientated the right way behind the driven plate

bad
flywheel doesn't have the three dowels it should have, this is easily rectified with a drill and a new dowel
clutch cover is not performing as it ought to

here in the UK the law states that the supplier of faulty goods (which certainly seems to be your problem) is liable to replace them with goods that are fit for the purpose they are intended to perform [dont hit me with the proper wording chaps unless I have been sadly (more than usual) mistaken, all these years]

So I would hope that QuantumMechanics have a good one "in the post" to you as we pontificate...

do they?

I think you have done all you could be expected to, to sort this out. Over to Quantum!

David B (UK) thanks for confirming what I thought, but, the MMC instructions specify cutting the guide tube off the front face of the gearbox. I presume this is so the closer-in fingers can operate without fouling.

It seems to me (inside my researching head) that we now only need to find out whether either of the two stated Ford discs can slide down the "spline-path" on the Type 9 gearbox, by which time we will have confirmed a source for driven plates for Type 9 conversions that enables us to buy at corner spares shop rates rather than inflated Big Shop prices
Bill

Bill,

The long sort after 6.5" driven plate with the 25.4mm x 22? spline (t9) has been mentioned many times but I have never seen anyone mention a standard application which is why I think it a special. The Ford plates you mentioned, at least the Escort uses a smaller spline, 19mm x 19 or something similar, it's given in the QH clutch PDF anyway.

David Barrett,

As your old cover works and the plate seems the right size have you considered removing the thrust plate and using that cover, maybe with opening out the central hole.
David Billington

Thanks again David

I wonder if the Fiesta plate would fit the type 9 application at 165mm

I must search for the Sachs and QH downloadable catalogues again

David (US) does the old cover plate fit without taking the pressure pad off?

I was told at the weekend that Rivergate advise knocking the pressure pad off the fingers to make it usable with their gearbox kit

The very thought makes my old knees water**

But it can successfully be drilled out from the centre if you have access to a lathe

** it must be applied "in factory" by distorting the fingers one way or the other
Bill

Quantum is 'supposed' to have an answer to whether a "heavy duty" direct replacement clutch is available.

If not I really dont feel comfortable just putting another of the same clutch back in there without any answers or changes. This is why Im considering a 7 1/4 conversion.

///David (US) does the old cover plate fit without taking the pressure pad off?///

What do you mean??
David Barrett

So david barret,

Are they going to send you a new disc or what....what direction are you going to go now. what have you determined to be the problem.


Have you figured out on the new disc the side that faces the flywheel ......

Why the face of the splime hub is worn and shinny,
Why the 6 springs have a groove cut across them and a bit of shine on the tabs that are holding the springs in....

after all those charteristics are not seen on the old disc in the same photo

bottom line ...its rubbing agianst something...I just dont know what,,,,what do you think the new disc is rubbing agianst.

see the photo

prop


Prop

The driven plate being held clear of the flywheel friction surface by rubbing on something as Prop believes would also have the effect of producing the "flat fingers" that just look wrong in the photo. They should only be that flat when the clutch pedal is depressed!
If you just hold the driven plate up against the flywheel, are you sure that the friction lining is the first and only part to make contact?

Guy
Guy Weller

Prop

To me your comment about the spline hub looking worn seem wrong, it just looks like it has been freshly machined with no further protective process applied as can be seen in the earlier 3 shot series showing the side shot of the plate.

Can you highlight where the groove cut is, the photo seems slightly fuzzy, but I can't see any evidence to indicate anything more than the usual slight rubbing you get on the springs from their housings.
David Billington

running this one through the old braynebox again, as you do, David (US) can you supply a photograph of the replacement spigot bush sitting in the flywheel cavity as supplied

If Prop's thinking is followed for a minute the centre spline unit "might" just be being held off the flywheel by the bush implant. My spigot bearing implant was fitted from behind the flywheel and assisted to "locate" by liberal use of Loctite Stud and Bearing fit adhesive, because I wasn't entirely sanguine about it resisting "push pressure" during first assembly.

Mine was a poorish fit in the flywheel and was a much firmer bet with the cyano assistance of the Loctite

It is visible inside the clutch cover in this shot but I cannot see enough to suggest it would foul the centre spline unit

http://www.flickr.com/photos/16060787@N08/2756174727/


The Ford based clutch cover (the second!) I used after the Midget one's diaphragm broke was far less thick at the pressure pad than the Midget one and did in fact have slightly flatter fingers when fitted than the MMC one fitted afterwards. It however broke during spirited gearchanging when dashing away from traffic lights, uphill.

Left me not only stranded but embarrassed when the cars I'd left became the cars passing me on the "wrong side"

But the spring plate broke just like the Midget one had, due to the "overthrow" clutch bearing situation. Too much pedal broke the plate.

David, if I was doing everything again, the 7.5" clutch redrilling is an option I would certainly consider. Your flywheel needs a redrilling for the dowel so you might as well see about going for the heavy-duty big cover option while it is in the shop.
Bill

To give an indication of the flatness of the 6.5" clutch diaphragm on my 1420cc A series I took this shot. The diaphragm fingers are flat or very slightly conical toward the gearbox in the centre. Sorry for the condition, while the clutch is still fitted to the engine, neither has been used regularly since 1997 and last run maybe 3 years ago. The cover is 1275, maybe heavv duty, plate used is 6.5" Ford Escort. Clutch has covered many 10k miles.


David Billington

>>>>>>>>>>>>If Prop's thinking is followed for a minute the centre spline unit "might" just be being held off the flywheel by the bush implant.<<<<<<<<<<<


EXACTLY and Thank You!!!!

It makes no scense that there is a protective coating on everything else except the face of the spine hub....the grooves that has been cut in the springs ...goes across the center of the springs,,,its small but easily seen esp. on the springs at the lower side of the disc....my guess is they are hitting the flywheel bolts....because even the bolts have a shine on the outer edges and not the inner edges....dont belive me ...agian look at the photo


agian what ever is rubbing is minor....we are only looking for a toleraance of about .30th of an inch (300ths of an inch) for this thing to scream down the road and slip like an elephant on ice skates

I dont understand why your so agianst the basic facts looking at you in the face, based on these photos....Just because the odds are extremely high that this IS the problem does not mean you cant go to the 7.25" upgrade clutch....Id do it in a heart beat myself...to many advantages not to and I wou;d use an aluminum flywheel also to get that extra 15 hp, plus addition engine life, and an extra 5 mpg in fuel economy.


prop
Prop

Prop, I understand exactly what you are saying. But the side of the new disc that faces the flywheel can in no way make contact with the flywheel OR the bushing implant.
If you look at the attached image in this post:


///David Barrett, Connecticut, USA
And heres a side shot of the discs.
As you can see the T9 disc doesn't have same wavy spring between the the two friction surfaces.///

Image



you can see that the splined section of the new disc is NOT treated like the rest of the disc and therefore looks as though it has been polished from some interference.
Also, the side of the disc you CANT see in this picture is VERY flat, that is to say it doesnt come close to the flywheel or the bushing. This is how I am certain I had the disc in correctly the first time, and that WASNT the issue. As I said before, if the disc was in backwards, it heavily interferes with the flywheel.
David Barrett

Here is a GREAT Idea....and the easiest way to find the problem.

load up the engine and tranny and the clutch system in the back of a pick up truck, tie it all down,,,and take it to a good tranny shop,, a shop that has been around along time and has seen it all....and have them take a good look.....most likely they wont charge you a thing....and even if they do its going to be under $25 tops.


As someone thats self employeed in the house painting and wall papering business for the last +20 years I get calls all the time from home owners wondering what went wrong on there weekend house painting project, and If there not far away, Im always willing to take alook and offer my advice and never charge them, a dime. Its just good busuness....trust me if they dont want to take a look someone else will.

After all, what do you have to loose. an hour or 2 of your time? and maybe $20.00


prop
Prop

Congratulations!!!!.... You Just found the problem....

1. We know that the disc and pressure plate are not defective and are the correct plate and are undamaged and have no manufacture defects. True!!!

2. we know for fact that there was no contaminate oils on the flywheel or the disc. and the disc was not installed backwards, true!!!

3 you have proven me wrong completely that there is absolutly no obstruction between the flywheel, the disc, and the pressure plate...the fly wheel has not been over skimed, the the face of the disc is sitting sqaurely against the flywheel and the pressure plate, and is not making any residule contact and the pressure plate is not broken ... all true!!!

4. We know your engine is producing somewhere around 100 -125 hp.....well inside the tolerance range for this tranny conversion set up, so your not over powering it...True!!!


THE ANSWER.....
So that only leaves 1 thing and one thing only....the slave push rod is to long and is not allowing the clutch to fully disengage....this can happen based on a whole host of problems...you will have to reassemble and install the engine now that everything checks out perfectly and we now know there never was a problem inside the bellhousing area and we can then attack the slave clutch push rod problem

There is absolutly no other reason that the clutch can slip on this type of set-up...NONE...This is the Awnsewer


once you get the new clutch upgrade complteted and have the whole thing installed...let us know so we can figure out why the push slave rod is pushing to far in.

Wow thank god thats over and we finally know what the problem is


Agian congratulation on finding the problem...I knew we would get there eventually

Prop
Prop

Hey David B.


Just another thought,

Comparing the Inside diameter of the throw out bearing vs. the outside diameter of the spline hub on the disc....are those tolerances vary close?

does the inside of the throw out bearing cover (go over) the spline hub of the disc when the clutch is DEPRESSED...pushed in for changing gears..... looking at the photos Im guessing yes


IF so I wonder if its hanging up abit so when you release the clutch its actually PULLING the disc backwards towards the rear of the car and away from the flywheel...thus allowing slippage....agian it wouldnt have to pull the disc away vary much....( .30 of an inch) is all. and you got slippage



prop
Prop

Prop, The slave rod is what I initially thought was the issue.
The first time I started the car after the conversion. I had it up on the lift. I pushed the clutch in and attempted to put it in gear. When I did so, it ground into gear just slightly. After some investigating I found that the pin in the master cylinder/ clutch pedal interface was pretty badly worn so I surmised that the exessive wear wasnt allowing enough pedal travel. After replacing the pin, the grinding issue was gone so I put the car up on the lift again, and checked for play in the slave rod....Which there was @ 1/8".

No, the space between the splines and the throwout bearing in not even close.
David Barrett

This thread was discussed between 09/08/2008 and 15/08/2008

MG Midget and Sprite Technical index

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