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Clunk on over-run - TR4A


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Hello, I've had this annoying clunk from the rear end on the over-run ever since I've had the car, over 3 years now, and I'm trying to tie down its source.

Originally I thought it was hub spline wear on the wire wheels but I replaced these some time ago. There is now 2mm play at the rims which I would have thought is OK. I can't feel any play in the half shaft UJs. (its an IRS)

However, there seems to be a lot of backlash in the diff. With one back wheel off the ground and the car in gear, I get about 25mm of play at the wheel rim before the prop shaft moves. So my question is, is this normal or excessive? The diff was a recon unit from Rimmers about 10k miles ago. Thanks, Brian.

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that free movement is the play/backlash in the planet diff gears , not the crownwheel and pinion  its quite normal as these gears transmit all the load but as the dont rotate much they have no cleaver meshing  as a crown wheel does .


this can give upto 1/8 turn on the prop or even more,  its normal.



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As Pete says, the driveline play doesn't sound excessive.... Coming back to the problem, it could be worn splines on the IRS driveshafts themselves - if they are worn and you are going down the replacement path it is worth considering some of the alternatives (need fairly deep pockets though!) with CV joints and ball bearing sliding shafts.

I changed to a Datsun120-based conversion on my old Stag and the difference was significant.


Are the trailing arm bushes in good order? If not Polys will tighten things up nicely.


...... Andy

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Hi. As you are talking about rear Bush replacement I was considering this as a winter job. Not done anything like this but understand a lot of grunt is required. Can you recommend the tools needed to take this on please.




most say it is a devil of a job to remove them, but on a couple i have done i just used some threaded bar, hefty washers and some tubing to 'wind' the old ones out and the new ones in, it wasn't so bad.


If anyone is interested i have got a set of new Blue SuperFlex IRS trailing arm bushes & inserts which I won't need - my 4 is live axle - £40 plus the postage if they are of use?


cheers, Andy

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I was very lucky to get hold of a set of Datsun converted driveshafts for a very good price complete with good hubs, the prices seem to have gone up recently... I know of a couple of folk who have fitted some greasing nipples to the driveshafts which at least make regular lub'ing less of a chore.

Ball-bearing/CV shafts get rid of two problems in one hit, but they do require some penny-saving!


Why not do the trailing arms Polys first and see if they improve things enough to not need to do the driveshafts immediately.... The shafts can be easily swapped at a later date without disturbing much if things are stil too twitchy.


..... Andy

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Hi Andy, yes there,s a plan in place, get the knees to work , get the back supple, make the tea

add the scotch !!!

It will be a careful look see , not going to jump into deep pocket sydrome

mine has the greaser but was off road for 20 years after a resto, so who knows

I knew the bushes were soggy when I bought her last year but concentrated on doing the front first with added p stg,

the backs not looking difficult but she still wanders and has excess rear toe,

have blue poly to fit, re track and pull the shafts

Big box of tea bags ready



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  • 1 year later...

An update (obviously I took a long time getting around to sorting this :-) I've since moved and the owner of my local garage is well up on classics so I got him to have a look. He had it up on the lift with another chap slipping the clutch in gear with the brakes hard on. He diagnosed play in the drive shaft splines as suspected.

After doing some research on the other TR forums I got some new shafts from Proptech in Hartlebury. They have splines coated with some sort of plastic, sealed and greasable, and GKN heavy duty UJs (I had to fettle the stub axle yokes somewhat to get the spiders in). So a bit of an upgrade, and not much more ££ than standard ones. The CV type shafts are about 4 times the price! I wouldn't think justifiable unless you have a highly tuned car and do lots of miles?


I also replaced that little spring at the bottom of the gearstick, so now I have a much less clunky and buzzy machine!



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