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Diff clunk


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I'm still trying to cure a clunk from the back axle on take up and over run. Last year I did all the UJs (good quality replacements), I've got a rather unusual prop shaft (Frictionless) (subject to earlier post), there's a bit of play but I don't think that is enough for the clunk. Where there is quite a lot of play is in the diff. With one wheel blocked and turning the other there's quite a lot of movement and a distinct knock. I'm wondering if its the splines on the inner drive shaft.

Any ideas on what is acceptable. Rimmers and Canley both say they are no longer available.

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the main things to wear are the thrust washers on the sun and planet gears  the free play is nothing to do with the crownwheel and pinion 

this wear  can give a bit of pinion rotation from drive to overun but as the gears only move slowly on corners its never a problem 

have you checked the state of the diff mounts ???

you dont happen to have wire wheels ???

 

Pete

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Diff mounts look OK. Yes I have wire wheels, but I thought that by jacking only 1 side up and with it in gear I could try rotating the wheel to see where the clunk came from. There is no noise from either wheel only the play in the diff as mentioned before.

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From bitter experience many years ago, and I then got rid of the wire wheels, it would be worth checking that the spline adapters for the wheels are actually tight on the hub and using the correct nuts, they have a different taper to wheel nuts IIRC.

Dick

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Advantage of the Rotoflex coupling it soaks up all wear, and noises, till it breaks!!

Always remember in the UK driving in a Uni Car Club rally, backing up then slamming it into first and going for it, you could feel the donut winding up then launch you out! no bangs no noises

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i would hazzrd a good guess it will be wheel /adaptor/spline  .giving the clunk  its common on wires 

the slack on rotating one wheel doesnt prove anything and is pretty normal on a std diff 

under drive the diff gear play has no effect 

you could spend a lot of time replacing thrust washers and still get the clunk 

Pete

 

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  • 1 month later...

I had a Mk2 Spitfire a few years back with an interesting clonk from the back on take-off. After a lot of head-scratching and wriggling about under the car, I noticed, almost by accident, that the new rear spring has quite a lot of clearance between the clamps and the leaves of the spring. What was happening was the leaves were moving on hard acceleration and hitting the clamps. I checked on another car I had with an original spring and there was no clearance. So I stuck some pieces of nylon in the gap......no more clonk.....

I wonder how many diffs have been replaced due to poorly manufactured rear springs....

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  • 2 weeks later...

Hi Chaps,

Word of caution and I hope this might assist:- because of a.n. other car failure, my Herald became or every day car.

I too, had a clunking from what I thought was the diff - or possibly a U/J on the way out and had only limited time to investigate (because how much time can you afford to have your everyday car off the road when rural- and with kids).

Trying to do the 'quickest' thing, I changed the half-shaft U/J's, as there didn't seem to be excessive play in the diff (Lucas Services had replaced years before).

But the clunk still continued. When I was away from home, my wife and daughter nearly had a bad accident as the rear drive began - we now know - to come apart.

At the diff end of your half-shafts is a yoke into which the U/J is inserted. You will note that the half-shaft, at the yoke end, is splined and pressure fitted into the yoke, with a cross-through-pin pressed through as security just in front of the yoke.

Well, I don't know what the chances are of that joint failing, but fail it did - and I have never heard of such an incident from anyone else ever. And while all the other rear suspension elements held together, that half-shaft caused all sorts of steering problems. Fortunately, there was no harm done except a very shaken couple of family members who were loathe to drive the car again.

I bought a complete, assembled half-shaft set from Brimmer Bros and fitted (old half-shaft came in handy to lever the leaf spring). Problem solved.

SO:- Please, please, check the half shaft security pins for veracity. BTW; not sure if those fully assembled half-shaft sets are still available, but they save a hell of a lot of grief when you consider all the other dismantling which would have to take place!

Best,

Colin 

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7 minutes ago, Colin said:

Hi Chaps,

Word of caution and I hope this might assist:- because of a.n. other car failure, my Herald became or every day car.

I too, had a clunking from what I thought was the diff - or possibly a U/J on the way out and had only limited time to investigate (because how much time can you afford to have your everyday car off the road when rural- and with kids).

Trying to do the 'quickest' thing, I changed the half-shaft U/J's, as there didn't seem to be excessive play in the diff (Lucas Services had replaced years before).

But the clunk still continued. When I was away from home, my wife and daughter nearly had a bad accident as the rear drive began - we now know - to come apart.

At the diff end of your half-shafts is a yoke into which the U/J is inserted. You will note that the half-shaft, at the yoke end, is splined and pressure fitted into the yoke, with a cross-through-pin pressed through as security just in front of the yoke.

Well, I don't know what the chances are of that joint failing, but fail it did - and I have never heard of such an incident from anyone else ever. And while all the other rear suspension elements held together, that half-shaft caused all sorts of steering problems. Fortunately, there was no harm done except a very shaken couple of family members who were loathe to drive the car again.

I bought a complete, assembled half-shaft set from Brimmer Bros and fitted (old half-shaft came in handy to lever the leaf spring). Problem solved.

SO:- Please, please, check the half shaft security pins for veracity. BTW; not sure if those fully assembled half-shaft sets are still available, but they save a hell of a lot of grief when you consider all the other dismantling which would have to take place!

Best,

Colin 

This was brought up a couple of years ago. And the )fairly new) shaft had been fitted with a roll pin to retain the yoke on the shaft, totally unsuitable. Worth checking you hav enoy been sold such a shaft, it needs a proper hardened pin in there.

Glad the occupants were OK, it would be a bit of a scary moment.

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  • 2 weeks later...

Thanks for the advice from the history of such a thread. I found it just easier to buy a complete half shaft assembly and fix up. Obviously hoping the pros have used all the relevant components icluding solid not rolled, pins.

The one that 'went', was fitted from new . . . 

Best,

C.

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