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MG MGB Technical - MGB clunk drivetrain

New to MGBs. Bought 1975 rubber bumpered GT. Car has developed a clunk when loading or unloading prop i.e braking/accelerating- noise free at constant speed? Is this likely to be prop, uj's or something worse?
P G LIDDER

PG,

Does it have wire wheels?

Charley
C R Huff

in my case clunks came from (a) slack in diff - can be rectified if moderate and (b) worn wire wheel splines. If the latter, suggest you don't replace just the splines - replace the wheels as well.
jc
J H Crighton

Usually differential slack as suggested. As also suggested, check hub and wheel splines carefully if you have wires - if the splines strip you have no brakes on that wheel!

Cheers,
Tim
T Jenner

With mine it was the UJ's that caused a noise like this. Get under and see it you can move the main prop relative to the flange. Any movement really and they need replaced.

Iain
I D Cameron

Thanks for responses. It has Rostyle not wire wheels.
P G LIDDER

And sometimes U-joints can be worn out but will be jammed up and don't reveal their slack if you are just trying to check them by hand.

Charley
C R Huff

Just to set your mind at rest, more Bs have the diff clonk than don't. It's most commonly caused by worn thrust washers and if so is nothing to stress about but if it gets too irritating the parts can be bought for £5 and an afternoon under the car will usually see it remedied. Lots of instructions in the archives. Hope you enjoy the car.
Steve Postins

Do you not need a special tool to stretch the case to fit the clonk kit?
Richard

You need a tool to get the whole differential out of a late axle, but the clonk kit is just thrust washers.
You take off the rear cover, drive out the roll pin securing the cross shaft, remove cross shaft, then wind the planet gears out.
You also need to pull one halfshaft out about 1/2" to get the gears off the ends of the halfshafts, but you can do this without stripping off the brakes and hubs if you are careful.
Martin Layton

I've got the same clonk but have an early axle. I read on John Twist's site that it's very rare for early axles to clonk unless something serious is wrong because they have copper thrust washers - should I be worried!?

Cheers,
Tim
T Jenner

"You need a tool to get the whole differential out of a late axle"

Not neccessarily, it may be down to individual axle castings having a smaller aperture. I lifted my diff out no problem, and I have heard of others doing the same. This was on an axle off-car as the shaft was simply too tight to get out, having driven it in as far as I dared.

Paul Hunt

When everything is new the spreader may be necessary to allow the diff assembly to be installed due to the preload on the carrier bearings. The preload slowly decreases as the bearings wear allowing the unit to be slipped out without special tools as Paul states above.
John H

T Jenner,
I've got a 65 with an banjo unit. It has more backlash than I'd like but it's remained that way for 15 years getting no worse. The universals are fine. I don't know if after all these years the differential gear thrust washers are shot or not.

I do have gear noise but it has also remained the same for 15 years so I've not gotten into resetting things. I just live with it. I think the banjo units are normally noisier than the tube axle types. I did got with synthetic hypoid oil which reduced noise at all temperature ranges. I've been very happy with it.

Unless you really push the car or the clunk is getting worse I'd live with it.

Bob McCoy
Now in New Hampshire USA
Robert McCoy

Thanks, Bob. My car's going to a specialist in a few weeks for a clutch and I was thinking of asking them what they'd charge to do the thrust washers in the axle whist they have the car. I confess I've never checked the rear axle oil level or changed it - perhaps that's a job for next weekend along with some sythetic. Presumably it's still marketed as EP90?

Cheers,
Tim
T Jenner

Hey guys...whatzamattter here? This is classic B-Clunk, solved in a 2 hour procedure by replacing crush washers on axle and the coppers sitting atop the spiders. Moss sells it all for about 2 sawbucks. This will eliminate of reduce the clunk. Check archives, it's a widely known phenom under " clunkectomy". Vic
vem myers

.....eh, sorry didn't mean to crumb the thread.......oh and use 70-140 synt hypoid on refill
vem myers

This thread was discussed between 19/08/2008 and 06/09/2008

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