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MG MGB Technical - Mating engine to gearbox

Hi.

I've fitted my new clutch but am having trouble mating the engine to the gearbox.

What is the knack to this (and don't say do it outside of the car please).

Regards,

James
J Elliott

Ps. I've got it in line with the rod as much as possible and the flywheel has clearance all the way around but it stops suddenly with about a 30cm gap between the housings.
J Elliott

Should I try getting someone to push the clutch pedal in as I didn't remove the clutch cylinder?
J Elliott

Okay...I got my dad to press the clutch pedal now the release bearings really far forwards...

Please help.

James
J Elliott

Don't have someone push the clutch pedal with the motor this far out. Last time I did that, I pushed the slave piston right out of the cylinder.

You're most likely fighting getting the transmission input shaft into the spigot bush. There's only a few thousandths of an inch clearance in the bush, so it's a careful fit. The clutch plate has to be lined up to the spigot bush very carefully. You did use a clutch alignment tool, then eye-balled the tool, still inserted, that it was straight and level. Right?

First, with spark plugs removed, turn the crankshaft a little - just to make sure it isn't simply that the splines are mis-aligned. Push the engine. Any luck?

That probably won't work. You've probably also tried wiggling the motor up and down and side to side without relief.

If so, then I'd take some long bolts and thread them into the holes where the bell housing meets the back plate. Snug each one up finger tight. Then with a tape measure, carefully measure the gap at each bolt. Find the largest gap, and twist that nut down a thread. Finger tighten the rest of the nuts again, and measure again.

Continue until all of the gaps are exactly the same. Then try to push the motor into place. If this doesn't do it, you can continue around the circle of bolts, twisting each nut down a thread at a time until you've pulled the motor in about an inch and a half. Then it should slide in the rest of the way.

Many will grimace at this method. Because if there really is something interfering with the two pieces mating, you can really mangle things. Make absolutely sure nothing's misaligned or in the way. If you get a lot of resistance when twisting a nut down, then stop, back the whole thing out and figure out why.

Matt Kulka

I see I type too slowly. Back the engine out a bit. Take the rubber cover off of the clutch slave cylinder. You'll probably find the piston has slid out and cocked itself against the end of the cylinder. If so, get this fixed and reassembled. If not, then just push the piston back in with your finger.

Then see if my previous post is of any help.
Matt Kulka

James,

I'm assuming by your comment of:

(and don't say do it outside of the car please)

that you're attempting this procedure with the gearbox already in the car? (he says obviously...) I'm not sure why you're doing it this way as it's been discussed in past threads that the preferred method is to mate the two components together first and then install in car (others can offer up their comments).

Regardless of that, as long as the clutch was installed with an alignment tool and is centered on the flywheel, with the help of a friend, the two components will slide together. Usually the problem is the misalignment of the input shaft of the 'box not lining up with the bushing in the back of the crankshaft. Doesn't take much to be off.

I don't know about having someone depress the clutch pedal. Best guess would be that this would just put more pressure on the clutch system and make the job more difficult.

Personally, I'd just remove the clutch cylinder. Two bolts removed and you can leave it attached to its hose (no need to bleed the system).

I remember doing the in-car installation once in the past and it was a "bit o'fun" getting it lined up. I believe I ended up drawing the 'box to the engine the last inch or so with the bolts. Probably not wise at the time (never did find out if it worked or not as I never finished the restoration).

Don't know if this is any help, James, just my ideas on your task at hand.

Cheers
Simon
Simon Austin

I found the best way was to get as close as possible to eyeball the input shaft to get it absolutely square on. Viewing from all angles helped get things in line first and when line of sight was lost feeling the position of the shaft relative to the spigot with my fingertips enabled me to call the "up a bit, left a bit" instructions to my patient assistant. It felt a fiddle with the engine dangling away, but only took about 45 minutes of cursing in reality. Check that the sump or something else isn't catching, but with a 30cm gap I would say that the shaft is still bouncing around the edges of the spigot.
Steve Postins

Right guys.

Thanks for your comments.

Piston is out of cylinder but I've removed cylinder now.

Took engine right out again to see if I hadn't aligned the friction plate properly.

Got a plastic tool when I bought it.

Realised that the alignment tool wasn't going right into the engine.

I removed the clutch plate again and tried with the friction plate out to put the alignment tool in. Wouldn't fit.

Tried to put the new friction plate on the gear shaft..wouldn't fit.

The bloody teeth come in too far!!

The aligment tool slots in perfectly with my old friction plate.

I bought the clutch early last year and have only just got round to trying to fit it. Didn't think I'd be this screwed over by the parts company.

Got to put engine back in car to close garage up tonight.

Don't think I've got my receipt any more :(

I'm starting to hate this now.

James
J Elliott

How worn is the old one? Is it worth using?When new the plate is about 8mm front to back if that helps, with the material about 60 thou (sorry for mixing measures) above the heads of the rivets. Otherwise, the weather forecast is dry for tonight.
Steve Postins

Hang in there, James! It's a real love/hate thing with our cars. You hate doing certain jobs at the time but you love the end result.

I just did the install of the windshield-to-body seal last night. Hated every minute of it but sure loved it when it was done. I don't think my wife knew that I could fire off so many swear words in 45 minutes.

At least she was smiling.

If you have the time, take your "new" clutch back to where you bought it. Most shops will help you get it straightened out.
Simon Austin

James,

You're not being screwed by the parts company. If you're sure you did everything correctly, and it sounds to me that you did, the trouble you are experiencing is 100% normal. With the engine and gearbox out of the car, the mating of the two can be very, very, very frustrating and then POP! they slide right together. It seems to me that everything must be 100000% exactly in line or it just won't go together.

So, understand that with the gearbox still in the car, it may be even more frustrating. They will go back together, just a matter of perfect, perfect, vertical and horizontal allignment. Good luck, I know you been at this throught all sorts of trials and tests of patients. May the MG gods be with you.

Paul
Paul Hanley

James, I've been there, done that..... If your problem is that the clutch plate will not fit onto your tranny shaft... (I think that is what you are saying), there may be some burrs on the teeth of the plate or on your tranny shaft or both that is causing you the problem. Make sure both surfaces are clean and not burred up.

The last clutch I changed had a similar problem and I had to use a small file and some emery paper to clean up the teeth on the clutch plate so it would fit/slide onto my tranny shaft. The old cluth plate slid right on but apparently the machineing (SP?)of the new one at the factory left a few burrs which was just enough to make it impossible to fit the clutch to the tranny. A little light lube to the two parts may help also.

I obviously removed the clutch from the engine to do the above tweeking..

My cluth was a Borg & Beck from a reputable dealer.

Hope this helps
Moe

Well I put the old friction plate back in and managed to mate the engine and gearbox with a lot of jiggling. However, I found taking the engine alone out to be quite acceptable even without a load leveler.

The new clutch is a Borg and Beck from Midland Sport and Classics.

Looks like I'll have to rebuild the slave cylinder to get the piston back in...is this hard to do?


Simon,

Thanks for the encouragement.


Moe (and Paul),

I can't even mate it when it's on its own being held to the tranny shaft.

Moe could be right with the burring but it definately wasn't even going onto the alignment tool..at all. I'll have a look tomorrow and take it into work for my colleague to 2nd opinion it (always nice).



Steve,

The old friction plate looked okay surprisingly..I mean the speckledy stuff on it was about 1.5mm thick on each side but it was very smooth (don't think that's important).

The clutch was slipping just about all the time before I decided to replace it.

The new release bearing has about 1.5mm granite produding from it...the old one was completely flat.




I'm going to bed now...next chance to have a go is Friday if I can get the friction plate sorted by then.

Many regards to you all and thanks (so far)..


James

J Elliott

Sorry..I wrote that bit about rebuilding the slave cylinder without thinking..I don't actually know what I'm talking about there...sorry. It's been a long day.
J Elliott

Hi James,

If it were me,...I would NOT use the old friction plate / clutch disc. As a "Golden Rule" of the MG world, EVERYTIME I ever had the engine out of my cars, I would ALWAYS replace the clutch assembly. It will be a false economy of time and money not to replace the disc. There is a slight chance that the old disc may be OK, but with all the headache you've had so far, I feel quite sure you wouldn't fancy having to do it all again should the disc not be OK. Remember, quality of a job is always more important than the speed of the job.

I know this is not the nest time to argue this point,..but it is ALWAYS easier to do this job by pulling the engine & transmission as one unit. That way, you can do all of the clutch work out in the open. Easy to see, easy to get your hands on, plenty of room to move around. The job is no harder pulling both units as opposed to just the engine.

Anyway, take a deep breath, clear your head, and good luck.

DT
Danny T

J: count the teeth in the center of the discs, measure the center of the discs, measure the diameter of the discs.If the measurements are all the same, inspect the splines you may have damaged them when you first tried to install the trans,if so, clean them up wiyh a file or get a new disc RIC
R E L Lloyd

James,

Are you saying that your old friction plate alone will fit on your gearbox input shaft but the new one by itself alone won't?

Assuming that the engine is away from the car, and you have dissasempled the new clutch assembly, will the new friction plate go on the gearbox input shaft? If not, perhaps you have been given the wrong one. Count the splines on both the new and the old. Are they the same?
Holds them both together and examine. Are they exactly the same spline arrangement?

Perhaps you have been given a 62-64 clutch plate. Now that I've read all your notes and exasperations more carefully, something does sound wrong. Are you using the alignment tool correctly? It should slide in and out of the clutch assembly with little to no resistance. Do the number of splines on the tool equal the number of splines on the input shaft and both old and new clutch plates?

You have a lot of folks cheering for you so maybe you could give an update before going on.

Paul
Paul Hanley

James. It is not uncommon that a new cluch plate will not fit on an imput shaft. As some have mentioned, there may be some burrs on the splined center section which will require removal with a fine cut file. Checking to see that the clutch plate actually fits on the input shaft before installing the clutch to the flywheel is one of those "general knowledge--everyone knows" things. Probably why none of us thought to mention it earlier.

I just mated up an engine and transmission yesterday with the help of a friend. It was a bear of a job, even though we had both laying out on a bench and could jiggle the tranny to slide it into alignment. Still took several tries. As has been mentioned, the difference in size of the input shaft and hole of the spigot bushing is .002"-.005". A thin human hair will measure .002", so you have to be exactly lined up to get the input shaft to go into the spigot bushing. One thing that helped us was the fact that we could put the tranny in fourth gear and turn the output flange slightly to help align the splines on the input shaft and the clutch plate. You can do the same by putting the car in fourth gear and having someone turn the rear wheel a bit to help alignment while you are pushing the engine up to the tranny.

With the tranny outside of the car, it is fairly easy to look at the two from the side and align them. With the tranny still in the car this is much more difficult. The bolts that hold the engine and tranny together are 5/16" diameter and the longest ones are about 3 1/8" long (the bottom two), which is just a little short to use as alignment pins. If, however, you could get some 5/16" bolts or rods that are about 4 1/2" long, you might be able to use them as alignment pins when installing the engine to the tranny. Do not know if it will work, because I have not had to try it.

The only simple, easy way to mate the transmission to the engine is to pay someone else to do it. Most of us do it ourselves, become frustrated, keep at it and get it done. You will to. Good luck. Les
Les Bengtson

I put the old friction plate back in with the new casing (and new release bearing) because I needed to put the engine back in so I could remove the engine crane, put the front wheels back on and push it into my garage to lock up for the next few days.


Les,

I might be common sense now but it wasn't then. I was following a haynes manual and I should have realise that the alignment tool wasn't going all the way in.

Putting it back in I did exactly as you mentioned.


As far as mating the two whilst the tranny's still in the car. The engine is actually quite mobile when on the crane so (especially with two people), they can be aligned nicely. To only difficulty is clearing the engine mounts as I couldn't remove either of them so had to manouver around them. It took about 20mins to get the old one back in.


I'm just about to count the teeth..after I get my morning coffee.

James
J Elliott

Paul,

As I mentioned earlier I took the friction plate on its own and tried to mate it to the tranny shaft but it wouldn't go, at all.

James
J Elliott

There are the correct amount of teeth.

The plastic alignment tool will go most of the way in from the flywheel side but only a bit in from the engine side.

It seems to be shaving a little of the alignment tool plastic off each time.

I definately tried quite hard to get it onto the tranny shaft the yesterday so it either needs heavy lubrication and brute force to get it on or it's badly manufactured.

Any guesses before I send it back to Moss (not Midland Sport and Classics)?

James
J Elliott

James. Best guess is that there were some burrs raised during the manufacturing process which interfere with the fit on the first motion shaft. Examine it under good light using a magnifying glass. If there are burrs, remove them with a small file, then try to refit. Several of us have had similar problems over the years. Not common, but not all that rare either. Les
Les Bengtson

Do you have the box with the supplier part number?

A wild guess would be (as mentioned) a mix up of a three main bearing plate with a five main bearing "style" of gear box.

The pilot of the 5 main is about 13/16 of an inch -- and 10/16 - (5/8) pilot on the three main.

Too, the difference is very small between the two at the initial spline alignment -- very approximate 31/32 for the five and 30/32 for the three.

All my precision measuring tools are out of reach, but perhaps someone will be kind enough to measure the two tools in the thousanths.

glg

James,

Sorry to hear you are having a few problems - here are a few points. The clutch disc must slip over the splines easily and you can check this before you fit it to the flywheel. It seems to me however that as you got the units to within 30mm that the splines had already been engaged and that it was only the spigot that had to be entered. If the splines had not been engaged the gap between the units would be nearer 75mm.

It is essential that the concentricity between the splines and the spigot bush are perfect and your alignment tool must be a tight fit in both to achieve this. I turn a steel mandrel that will just slip through the I/D of the splines and is also a very good fit in the spigot bush. You can then fit the pressure plate and bolt it to the flywheel. The mandrel should still be a good fit between the mated disc and flywheel after tightening and so there is no need to ensure that it is at right angles, it can't be anything else.

Now the problem, the end of the first motion shaft on the MG has no chamfer and this can be a problem, most cars have a chamfered shaft to ease entry so the best option here is to make a small chamfer of about 1/16" at 45 degrees using an angle grinder with a fairly fine disc. I can already hear people cringing out there but as an engineer can assure you that this would be good and normal practice. The shaft is made from a good quality material and it will take a few minutes to remove the required material. Both my B's have this mod and engine replacement is a doddle.

Personally I would be very reluctant to put any bolts in at all as you could risk damaging the end of the bush. Parallelism is easily achieved by eyeing the gap between the backplate and the bellhousing all round. Adjust the gearbox jack to ensure this is correct and the engine should just push home easily.

Finally James, don't be tempted to use some new and some old clutch parts, that's a huge mistake and you will only have to take the whole lot out again and I don't think you are up for that !!


Best of luck
Iain MacKintosh

When I put my engine back in(seperate from gearbox) it took only a couple of minutes of jiggling.

I found the best way to mate them was to put it in gear, jack up the rear, and turn one of the wheels while my assistant mated the gearbox and engine together.

Simple.
Matt

It's already back together because I had to take the front wheels off and have the car sticking out of the garage to have enough space to pull the engine back on the crane.

My car has a chamfered shaft and I didn't have any problems getting the old clutch back in..not that I'm going to use it like that, just while I get this sorted.

It got stuck before the teeth went into the friction plate teeth because I was able to rotate the flywheel freely from the front of the engine. I think I said about 30cm, not mm. More like 20-25cm. Before the flywheel teeth went into the bellhousing at least.

As I said before..I couldn't fit the new friction plate onto the tranny shaft at all and I can't get the alignment tool right the way through the friction plate because the hole's too small or something.

The box says Delphi Borg & Beck, code NHK9695. Moss code GCK109.


James
J Elliott

Iain,

Bottom line is that the friction plate doesn't fit over the tranny shaft easily. I can see a couple of burrs which might explain it.

Shall I send it back or try again?

James
J Elliott

James,

I have a three main clutch cardboard box from a previous install. It says NHK 9694 but the Moss code is the same as yours GCK 109. Bottom line--Your post above says it "plate doesn't fit over the tranny shaft easily". Does it fit at ALL?

Paul
Paul Hanley

I managed to get it a little bit on and it jammed there. By little bit I mean a couple of mm. I can get it further onto the the alignment tool. The plastic is getting a bit shaved off from me testing though so this might explain it.

Can only see 1 burr. Will try and emery this then have another go maybe.

James
J Elliott

James,

Remember that in order for the clutch to work properly the friction-plate splines must be a smooth sliding fit over the transmission input shaft. In use it slides back and forth on this shaft almost constantly. If your new plate is binding whatsoever with this shaft I would not use it. You are probably lucky the fit is so bad, otherwise you would be trying to determine why your new clutch was so stiff in action and not engage, disengaging.

Sounds like you have no problems getting he engine in and out when things fit properly.....probably time to get a new friction disk.

Cliff

p.s. have you checked the fit of the T-O bearing fork as it mounts to the trans case? If the bolt and bushing become even a bit worn this can effect the clutch feel and action in use. Not usually huge thing, but you can only check this with the tranny out of the car and you can get a bolt and bushing rebuild kit for under $10.
Cliff Maddox

Cheers Cliff.

Will get it sent back to the shop today.

Regards,

James
J Elliott

Hi,

Personally I would take the transmission out of the car, use a couple of 4 1/2 inch alignment pins (take a couple of bolts and cut the heads off,) screw them into the back of the block ( one on each side)using the same holes that are used to secure the trans to the engine, and slide the trans along these pins and up against the block.Remove the pins and install the proper bolts. Lift up the BACK of the car and shove the whole apparatus into the trans/engine compartment. Bolt everything back together. I would not waste a whole lot of time screwing around under the car trying to align the splines etc. I have used this method several times, replacing clutches, transmissions, and rear seals etc.. A few years ago, by myself, I took the engine/trans out, replaced the old 4 speed with an O/D unit, new clutch assembly and TO bearing. Started work early one Sunday morning and was driving the beast at 5:00 PM the same day. Lots of work, but easy to do. Get a length of chain and a hoist (rent it) and just attack it! FWIW Alan
Alan

Since I don't think anybody has yet mentioned it...

After aligning everything up, I always, set the
transmission in gear (any gear will do, but
3rd or 4th works nicely).

When mating the engine & trans - twist the drive
flange (tailshaft flange) by hand...and "thump!"
everything goes together nearly everytime.

Sometimes a new pilot bushing (spigot bushing)
will make for a tight fit for the trans input shaft but
a good dose of patience is needed here.

If the clutch disk will not slide onto the trans input
shaft easily & smoothly - do not install it - do not
file or fiddle with the part to force it on. Get another,
proper part. You don't want to do anything slipshod
inside of the bellhousing, or else you'll be hauling
everything out of your car in soon order.

You DID replace the engine rear main seal and
transmission input shaft oil seal and gasket?
(it saves your driveway from oil spots later on)

Maybe your car is resisting you because it really
wants to try a TR-7 clutch disk on this go-around?
It fits. It's slightly bigger in diameter and has more
friction surface. It covers the entire surface of the
MGB clutch plate, whereas the MGB disk leaves
about 1/8" - 3/16" radius of the clutch plate
exposed and unused.

Daniel Wong

Alan,

I'm quite happy doing the engine only..I've done it once this way anyway!

The cranes legs won't fit at the front of the car without the front wheels off so I didn't want to have the front and back on Axle's at an angle..another reason I chose to do it this way.

I'm certain that the friction plate is at fault so am returning it (ran out of time today).


Daniel...I did do it as you said..worked a treat (with the old clutch being reinstalled :( ).

Hmmm TR7 clutch...does it cost a lot more? Surely that would weigh the flywheel down..

Will probably have a K-series in it by the time this new one wears out (probably).


James
J Elliott

James,

Glad that's settled! One very easy, no money thing that also needs to be done: lubricate the spigot bushing in the rear of the crankshaft. Just before reassembly take the amount of axle grease that will fit on your little finger tip and swab the bushing. Wipe any excess.

Others may have a better idea on this but typically the bronze bushing would be soaked overnight in motor oil before install. This came to my attention because on a previous install of mine, I didn't know about it, the bushing went dry, and the car would make a horrible scream when depressing the clutch when cold. FWIW

Paul



Paul Hanley

James,

Bottom line is that the clutch disk wont go on to the shaft more that 2mm. It's either wrong or faulty. Send the thing back.

Now, shaft, spigot bearing, fork etc have all been there before. No problem, just sort out the disc and you've cracked it.

Iain
Iain MacKintosh

J Elliot,

The TR-7 clutch disk - only - fits the MGB.
Not the clutch plate. The MGB clutch plate
is still employed here, and will work along
with the TR-7 clutch disk.

Except for it's slightly greater outside diameter,
the TR-7 disk is visually identical to the MGB disk (same number of springs, same number of
splines, same hub configuration, etc.).

Some owners who've made this swap have reported that this setup feels a bit more
"grabby", but is easy to get used to.

The TR-7 disk shouldn't weigh too much more
than a MGB disk. We're talking a mere few
ounces.
Daniel Wong

Well you'll be pleased to hear I made a personal visit to Moss Bristol yesterday and they agreed that there was something wrong with the plate I'd been sent but also couldn't immediately see what it was.

They gave me another one and I immediately tried it with the alignment tool I'd brought down and it slipped on no problem.

I guess it's all part of the learning curve...will get it fitted tomorrow (hopefully).

Thanks for the info Daniel (and everyone).

Decided not to bother with a TR-7 plate as couldn't think of any major advantage - and I'd already invested in this one.

Regards,

James
J Elliott

Hi..got the replacement fitted today...

Not too many problems..all caused by me doing it all on my own but finished and now time to figure out what to do with clutch slave cylinder :(

Thanks for all your help,


James



Ps...The new friction plate fitted fine first time but trying to mate it to the gearbox must have slighty damaged the very end of it as after trying for a while it still wouldn't go.

Took it out and the alignment tool wouldn't go in.

Took the friction plate out and rounded off the engine side of the teeth with a fine file and it slipped on fine.
J Elliott

James,

I hope you're headed to the pub for a few pints!! You've got the perserverance it takes. Congratulations. As far as the slave rebuild, (and anything else, considering what you've been through)is just dirt easy. I don't remember all the specifics of the rebuild but I do remember it being very very easy. I believe it's just the one round seal, the dust cap and a clamp. The one trick, of course is to remove, rebuild, attach the flex hose and tighten all conections before bolting to the gearbox. Cheers to you mate.

Paul
Paul Hanley

James,

Congratulations on collecting your first war story! As Paul says, your victory tells a lot about your tenacity - a valuable commodity for the MGB owner.

As to the clutch slave - it's only four or five pieces. Should be simple.

Make sure the cylinder isn't scratched. If it has a shallow scratch, you can try to hone it out. If it's deep, forget it and buy a new unit.

The piston itself doesn't do the sealing, so it's side surfaces are less important. As long as it doesn't have a gouged piece of metal sticking out which will scratch the cylinder, you should be okay.

The rubber piston seal is what seals against the cylinder, so make sure it isn't nicked. If so, then install a rebuild kit.

Based on what you said, these pieces are probably fine to reassemble. Use brake fluid liberally as assembly lubricant. Paul Hunt has tips for bleeding. Check his web site for details.

Again, Congratulations!

Matt K.
Matt Kulka

This thread was discussed between 06/01/2004 and 13/01/2004

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