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Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 6:20 pm
by Mr Bridger
OK, so I think I know the answer to this one, and it's not going to be cheap, but.... my 5a has started clunking from the back when power is put on/off. I've checked the UJs on the prop shaft for play and they are fine. The backlash between when the diff input flange is moved and when one of the rear wheels starts to move is not excessive, but not great either - I think. But while I can do most things on a classic I know very little about diffs.

The diff does whine a little, but only with power on and between about 32 - 42mph, apart from that it's quiet.

So having admitted I'm clueless, any ideas where I should be looking/the likelihood of me being able to fix it?

Thanks

Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 6:45 pm
by Coupe Racing
Check there is oil in it , check the pinion nut is secure then leave it alone

Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 6:47 pm
by BigBobPilot
Have you checked all the trailing arm & Watts linkage bushes? That would be my first candidate for clunking, follwed by damper bushes and/or dampers themselves.

Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 8:56 pm
by philhoward
Another vote for trailing arm bushes - they make an awful noise when they get sloppy. When one of mine started to fail, it sounded like the axle wanted to come through the floor!

Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 9:30 pm
by gtcse8
I still have a few ORIGINAL Metalastic bushes left from when I had BRT remake them for me.

Everyone seems to talk about the polyurethane replacements but I have yet to drive a car with those fitted.

Anyone Know Anything About Differentials?

Posted: Thu Jun 14, 2018 10:23 pm
by Mr Bridger
Well, I got all excited there for a minute. I started leavering things around and found that Watts linkage bracket was very loose on the diff. So I tightened the four bolts up, put the wheels back on confident of success and when I let the clutch up.... clunk. :evil:
I did have a fair old go at pushing, pulling and twisting the trailing arms about and they seemed pretty firm, but over the weekend I think I’d best remove them for a better look. Thanks for the suggestions by the way. They’re all better than a knackered diff as I had feared.

Right, if I’m quick I might just catch last orders. :P

Anyone Know Anything About Differentials?

Posted: Fri Jun 15, 2018 5:42 am
by Rev Light
Please let us know how you get on.

I also am in possession of a 'clunk' from the rear.

Steve

Anyone Know Anything About Differentials?

Posted: Fri Jun 15, 2018 9:54 am
by b.c.flat hat
Dear All
Congratulations on hearing your clunk, your car is now among those rare possessions that are valued beyond their actual worth. The noise you heard is it's depreciation bottoming out, ricocheting upward towards its owners sublime smugness. It is the focused object of every driver of a modern vehicle to attain their own clunk but takes decades of care, determination and skill unknown to the present generation. Cherish it, be warm in its presence, enjoy its reassuring repetition and subtlety.

Ps, I'm not one for bragging but I've had mine fer ages. I've checked all the above and further up the transmission too but found nowt that stops me fra' raggin' the nuts orf it round sprint tracks. Corse I've still got that uneasy feelin' that summuts gona go bang bigly!
Best ignore it then?

Anyone Know Anything About Differentials?

Posted: Fri Jun 15, 2018 10:10 am
by toolmanchris
b.c.flat hat wrote:
Fri Jun 15, 2018 9:54 am
Dear All
Congratulations on hearing your clunk, your car is now among those rare possessions that are valued beyond their actual worth. The noise you heard is it's depreciation bottoming out, ricocheting upward towards its owners sublime smugness. It is the focused object of every driver of a modern vehicle to attain their own clunk but takes decades of care, determination and skill unknown to the present generation. Cherish it, be warm in its presence, enjoy its reassuring repetition and subtlety.

Ps, I'm not one for bragging but I've had mine fer ages. I've checked all the above and further up the transmission too but found nowt that stops me fra' raggin' the nuts orf it round sprint tracks. Corse I've still got that uneasy feelin' that summuts gona go bang bigly!
Best ignore it then?
Oh the clunk - yes they all have that sir comes as standard across the range at no extra cost :-D

Anyone Know Anything About Differentials?

Posted: Fri Jun 15, 2018 10:25 am
by mark rudder
Hi all. Mark from downunder here.
I can one up that, I've a clunk & a whine, After a rebuild!

Anyone Know Anything About Differentials?

Posted: Fri Jun 15, 2018 10:28 am
by Nick
The Classic answer is to turn up the radio.................... If all is secure, and there is oil, I would leave it alone.