Sources of drive train slack
Discussion
I have had some drive train slack in the car since I bought it and it's steadily got worse, probably worsened by the shunting. From underneath, I can't rotate the main driveshaft or the half shafts by hand in either direction so those seem fine. Where else could this clonking be coming from - what are the common culprits: gearbox / diff ?
A garage has offered to "ball pein" and refit the hub ends of the halfshafts but I would have expected to be able to feel the slack in the half shafts by hand a few degrees or so if those were the problem.
A garage has offered to "ball pein" and refit the hub ends of the halfshafts but I would have expected to be able to feel the slack in the half shafts by hand a few degrees or so if those were the problem.
I had this and took me a very long time to find
I was a knock coming on and off the throttle
I checked all bolts were done up tight on whoel drive train, and it still done it!
But it turns out the 4 bolts holding the diff have allen keys at the back and hex nuts at the front, I checked the nuts when i did my checking and they were tight.
But the hex nuts are only locking nuts once the allen head has been done up
So what i did was loosen the hex nuts to find my allen bolts were loose once done up then tighten the hex nuts
I was a knock coming on and off the throttle
I checked all bolts were done up tight on whoel drive train, and it still done it!
But it turns out the 4 bolts holding the diff have allen keys at the back and hex nuts at the front, I checked the nuts when i did my checking and they were tight.
But the hex nuts are only locking nuts once the allen head has been done up
So what i did was loosen the hex nuts to find my allen bolts were loose once done up then tighten the hex nuts
Thanks for the ideas. I have the same with the Range Rover but its real obvious where the slack is as the propshaft can be rotated a few degrees back and forth but the half shafts do not, so slack in the diff. The TVR doesn't do this however, all shafts seem rock solid. Perhaps I should try the same with the rear wheels off the ground and rotating the shafts and then reversing.
You're right though Alex and Dr Ox, it is when coming on off the throttle. It didn't used to be too bad but since the clutch has been changed (not quite right) it is worse and now I can't tell what's due to the original and what's been introduced as a result of the clutch change.
How can you test the diff mount bushings - just lever it around a bit ?
Are they touch to change - I have a sets of spares.
Maybe it is gearbox mounts as I have had a squeeking noise when going over bumps ever since I had the clutch changed. I had guessed that it was the shocks which had been put through more travel than normal as a result of being unloaded (gearbox coming out).
You're right though Alex and Dr Ox, it is when coming on off the throttle. It didn't used to be too bad but since the clutch has been changed (not quite right) it is worse and now I can't tell what's due to the original and what's been introduced as a result of the clutch change.
How can you test the diff mount bushings - just lever it around a bit ?
Are they touch to change - I have a sets of spares.
Maybe it is gearbox mounts as I have had a squeeking noise when going over bumps ever since I had the clutch changed. I had guessed that it was the shocks which had been put through more travel than normal as a result of being unloaded (gearbox coming out).
Edited by taylormj4 on Thursday 10th November 14:24
below the belt!
So the source of the drive train slack or clonking has finally been solved thanks to Stuart and the team at Forza West. 
Part of the problem was diff bushes as suspected but the main clunking, the one that became apparent after a clutch change (that was done by a local garage) was the flywheel bolts.
Yes, the clutch had not been bolted to the flywheel tightly !
Local garage could not trace the source of the problem and suspected the drive shaft splines were worn. Hmmmm.
Not good.
Car now much nicer to drive, still shunts slightly now and again but no clonking. Just glad it wasn't the gearbox. Had been avoiding using full throttle in case I destroyed something in the drive-train. I guess fuel consumption will be poorer now though
Part of the problem was diff bushes as suspected but the main clunking, the one that became apparent after a clutch change (that was done by a local garage) was the flywheel bolts.
Yes, the clutch had not been bolted to the flywheel tightly !
Local garage could not trace the source of the problem and suspected the drive shaft splines were worn. Hmmmm.
Not good.Car now much nicer to drive, still shunts slightly now and again but no clonking. Just glad it wasn't the gearbox. Had been avoiding using full throttle in case I destroyed something in the drive-train. I guess fuel consumption will be poorer now though
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