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MG MGB Technical - Uh oh...........clutch slipping in 4th gear

Oh well........I guess it was bound to come up sooner or later. I got a solid 2 summers of great driving out of the 73B roadster before this came up so should be plenty grateful of that. Plus now I've done a whole lot of other mechanical work on it so am "ready" to tackle the big job! The only other time I've pulled an engine out of an MG was when I had my 66 back in the early 70s.

Symptoms: when driving up an incline in 4th at about 35, if I try and accelerate the clutch will slip casuing the car to remain at about 35, while the engine races up 500 rpm or so.

So, plenty of info out there to help me though this, but thought I'd pop a couple thoughts here and see if I'm on the right track.

1. It is better to pull the engine/trans as a unit then to try and drop the transmission. Correct?

2. While it is out, I'll do the following:
a. New clutch and all related components
b. Already did the clutch hydraulics so can skip that.
c. Oil sump gasket
d. Engine mounts
e. Maybe pull components off one side of the engine compartment at a time and clean and paint the compartment walls (car was originally red ..... now white....and this was all sprayed with some sort of undercoating like black gunk to hide the red by the DPO)
f. clean and paint(?) the engine


Should I do the following:
a. Front and rear engine seals
b. Oil pump
c. Water pump
d. Timing chain

What else should I consider looking into. The engine runs great.... good uniform compression and plenty of power.....so think that pulling the head, doing a rebuild etc. are not needed at this time.

Thanks,
BH




BH Davis

It's a slippery slope, isn't it? Once you start looking at oil pump and timing chain, you'll look at bearings, rings, etc. Unless it's leaking and you just have to replace seals I'm not sure I'd crack the engine open. Actually, that's a lie - I'd crack it open anyway since I have an addictive personality and don't know when to stop. Hopefully you're smarter than that. :(

I ended up paying somebody to do the tranny work on my car since I simply didn't have the facilities to do it myself when it needed doing. I think, though, you'll find that you'll get 99-to-1 in favor of pulling everything together.

Regarding the transmission: Assuming you have extra cash laying around (doesn't everybody?), have you considered a 5-speed conversion? I now have the Rivergate Datsun conversion in my '73 B, and truly think it's the best thing I've done to the car, other than the engine rebuild itself.

R.
Rick Stevens

BH - My one caveat would be to stay away from clutches labled "heavy duty". They are only good for racing, a heavy pedal and wearing out throw out bearings in a very short time. Cheers - Dave
David DuBois

Should I do the following:
a. Front and rear engine seals
b. Oil pump
c. Water pump
d. Timing chain
-----------------------------------------------------

a) YES - and would also suggest renewing front and rear seals on transmission. You'll need a new gasket for front transmission plate.

b) Perhaps - if you're going to change out the sump gasket. But, as Rick suggests, then why not the bearing while I'm here. WARNING - SET YOUR LIMITS BEFORE YOU START. Otherwise, you'll find yourself rebuilding the whole damn engine.

c) Only if you have a bunch of miles on it. But, a replacement might not last as long as one that's on it now.

d) It's a good time to renew timing chain and tensioner (don't forget the gaskets).

OTHER SUGGESTIONS:

e) Renew transmission mounts

f) Renew clutch lever (fork) bolt/bushing (if worn) and boot.

g) I usually remove shift tower, disassemble, clean and lube all moving parts. Refit with new gasket. Also, check you shift lever bush (plastic).
Steve Buchina

Thanks Steve and everyone else.
BH
BH Davis

I prefer to pull the engine on its own.

You don't say whether it's an overdrive gearbox or not?
Dave O'Neill 2

Dave,

Sorry.....thought about mentioning that but didn't. I "wish" it were an overdrive gearbox.....but it's not.

BH
BH Davis

BH

Just thought I'd ask, as it's not uncommon for an overdrive to give the symptoms of a slipping clutch...obviously not in your case ;o)
Dave O'Neill 2

Bill,

Make sure you get a Borg and Beck clutch. Some other clutches are not up to the task (dodgy quality). I like to use the MGB pressure plate and throwout bearing, but a TR7 friction plate, as it has the same splines and friction disc ID, but a slightly larger OD. Greater friction surface area = can transmit more torque and lasts longer. It's Moss part number 071-302.


Paul K

Engine only for me too - saved a lot of work/time. 98-2!
Steve Postins

Are you saying that you pulled the engine and then replaced the clutch with the gearbox in place?

Thanks,
BH
BH Davis

Yep.

You have to split them anyway, so why got to all the trouble of removing the 'box when you don't have to.
Dave O'Neill 2

BH

While you have the engine/transmission may as well paint the engine compartment. Bugs me when someone changes color and does not do under the hood.

When I installed my OD unit, I changed the mounts (transmission and engine). Pulled the pan to look at the lower end. It was in good shape, so just redid the gaskets and seals.

Took off all the accessories sealed everything up nice and cleaned the block and put on a nice fresh coat of paint. (beware of moss paint, nice color, but if you get coolant on it, it turnes orange)

Had the ring gear changed and surfaced the flywheel. (mine is a 67 and the starters are hard on the ring gear)
BEC Cunha

This thread was discussed between 07/10/2007 and 13/10/2007

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