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MG MGB Technical - clutch replacement

The ugly throw-out/release bearing noise in my 77B has inconveniently reach the "big" problem level (it was suposed to wait until winter).

I need to replace the bearing and clutch/pressure plate. Everything I read says that I must pull the engine to do this, but ... why not just drop the drive shaft, unbolt and slide the transmission back and out. I understand that it is more complicated than that, but ... PULL THE ENGINE!!?!?!

What gives?
Bob Duke
Bob Duke

Bob,
I don't know how much time you've spent under your B but I can guess it hasn't been a lot. Otherwise you wouldn't be asking this question as it should be rather self evident. Ok, enough of my condecending remarks, now onto the real answer.

There simply isn't enough room in the transmission tunnel to do what you propose. There also happens to be a welded in crossmember that runs right underneath the gearbox about halfway back. So even if you happened to get the gearbox back far enough, you still couldn't drop it down. Sure, technically it's possible as I had a '70 GT where the DPO had once cut out the previously mentioned crossmember in order to avoid pulling the engine. I don't know if it was successfully accomplished but there were cut and weld marks to indicate that they at least tried it. I wouldn't recomend it as you're beginging to mess with structural pieces of the car at that point and you probably won't save that much time in the end.

Once you've done it a few times it shouldn't take you more that a few hours total max, even at a leisurely pace. I've heard some people are pretty quick at it but I've only done it once and soon to do it once more.

Just my two or three cents.

-Jared
Jared Snider

On the late B's, I've read in several places that
it is possible to remove the non-OD transmission with
the engine in place. The bellhousing to rear plate
bolts are removed, and the gearbox can be rotated
and removed. If you have an overdrive, this just
isn't possible.

That said, its crazy not to pull the engine to
replace the clutch. In fact, I find it best to
pull engine and gearbox together. A clutch
replacement on these old cars is a good opportunity
to fix many other problems. You will probably want
to replace the rear engine seal, front gearbox
seal, front gearbox gasket (use some hylomar),
maybe motor and gearbox mounts, etc. etc.
Ronald

I have a nissan 5 speed in my 74 bgt and i have pulled only the trans. It is not easy, but i did it. The rear of the trans is over the support in the back. You would need help and have the car high in the air. I put the car on a lift to do this. We had to move the trans back to clear the flywheel/clutch, rotate it and then go forward. I would not do it that way again.
steve

Bob-
Listen to what Jared and Ronald are telling you. I've been working on these cars for thirty years and I'm telling you that they're dead right. Pulling the engine and transmission out as a package isn't really that difficult if you just take your time and work systematically. Once you've got the package out you can replace the rear main seal on the engine and the front seal on the transmission as Ronald suggested. This is standard practice and will save you serious headaches down the road (pardon the pun). It also affords a geat opportunity to do some general cleaning of the engine and engine compartment (Cleanliness is next to Godliness, you know!) Who knows, the worst that can happen is that you just might come down with a case of the "Might-As-Wells".
Steve S.

I just replaced the clutch in my 1970 roadster a few weeks ago. I simply can't imagine trying to remove the transmission without the engine. It would only be possible, I think, if you can get the car six feet in the air and use a transmission jack. Doing it while laying on your back on the garage floor would be dangerous. The slightest slip and you could be pinned by a falling transmission. Plus you have to worry about supporting the rear of the engine.

I agree about the "might as wells". You might as well replace the rear engine seal, the oilpan gasket, the transmission front seal. You might as well clean things up and repaint the engine. You might find that your flywheel is scored and needs to be resurfaced, just like a brake cylinder or rotor. You might find that the ring gear on the flywheel is in need of replacement. All of these things are easier with the engine out of the car.

I had a lot of trouble getting the pilot bushing out of my crankshaft, even with the engine out of the car. I can't imagine doing it with the engine in the car.

Pulling the engine and transmission together is really not that difficult on these cars.
Paul Noble

This thread was discussed between 18/08/2002 and 19/08/2002

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