WestOzGTA

When slowing down to a complete stop, just before stopping (like 5kmh) I sometimes hear some clunking coming from my drivetrain somewhere. Usually it's worse under heavy braking, and I often hear clunks and an almost scraping sound when reversing. It's not a broken tranny mount, because I recently swapped out the old damaged one and I've still got the same noises.

There's a bit of freeplay in the shaft - no more than 1/4" either way - but the uni joints seem ok. The whole drivetrain turns including the yoke and where it goes into the tranny.

What's the most likely culprit, and what can I do to check this out?

Thanks,
Stu

xplane

check the engine mounts. mine did that too i changed the trans mount and it was still doin it so i proped the hood up and did a power brake and i thought the engine was gonna jump out turns out that the engine mount being gone cause the whole assembly to twist and thats what broke my trans mount. also check your front wheel bearings i just replaced mine and didnt get them tight enough and when i would slow down or hit a bump the wheel would shift and make a clunk. just jack the car up and jiggle the wheel to see if it shifts.

Siggy

When I first got my 88 IROC it would clunk as I slowed, I researched this form and found that some early bins had lower speed switching for the T/C. I switched to a ARAP bin and used slightly higher T/C speed settings which gave much smoother results. A form search should find advice regarding T/C control.

madathlon

Im also chasing down a clunk for the rearend.. ( I think its from there ) .. But what are u talking about here???

Siggy

I'm referring to the Auto trarnsmission TH700R4 torque converter lock and unlock clutch operation.
My original ECU/Eprom bin ACXS had the clutch lock/unlock speeds set rather low (21 mph). I installed the Arap (later L98) bin which contained the higher speed settings for the lock/unlock functions. This released the clutch earlier and got rid of the clunk I use to get when slowing down. I not sure if this is a fix for westozgta, but hey it helped me.

WestOzGTA

Given that I've got TCC problems at the moment, possibly... but it does it at low speeds (eg when backing out of a parking space after the car has just been started) when the TCC definitely hasn't been locked.

But thanks for the extra idea anyway... it could well be a contributing factor.

I think my free play might be the tranny output shaft bearing and/or diff... though I'm not sure how I can check...