clunk/thump when pushing clutch at low speeds

[davem]

If you have a lot of backlash in your ring and pinion setup (in the diff) this can happen at low speeds when getting on/off the throttle.

I don't remember this when the car was an automatic though... is it possible that it is flywheel/clutch related?

[Wanganstyle]

If you have a lot of backlash in your ring and pinion setup (in the diff) this can happen at low speeds when getting on/off the throttle.

[russhixmo]

Mine does it when u put it in gear and take it out and let the clutch up too fast, i dnt think it's anything to worry about though

[davem]

I had the same exact symptoms and it ended up being really badly worn subframe bushings.

Mine are brand new.

[VinniE30]

I had the same exact symptoms and it ended up being really badly worn subframe bushings.

[davem]

Shit, didn't realize that this post was originally made in the 24v forum. Can a mod move this, or perhaps make it into a new thread? Sorry!

[davem]

I have this same issues... pressing the clutch pedal when I'm driving at low speeds and low rpms (parking lot situations for example) results in a loud CLUNK. I did some experimenting today and noticed that if I accelerate from stop with a lot of throttle/revs and then press the clutch it doesn't clunk, if I wait until the revs go down to about 1000k rpms and then press the clutch, CLUNK!

Info about the car - the maintenance mentioned is all recent and didn't change the symptoms (although this never happened when the car was an automatic).
-auto to five speed swap
-no clutch return spring on the clutch pedal
-new slave & master cylinder
-clutch, t/o bearing, pilot bearing replaced
-shifter bushings replaced
-new guibo
-remanufactured drives shaft and new CSB
-subframe, rtab, differential bushing replaced
-strut and shock mounts replaced
-shocks replaced
-one of the cv axles was replaced for one in slightly better condition
-transmission mounts

[static]

it's not SFB, RTABs, not rear tower mounts and not driveshaft bearing - all these had been replaced by both of us during the swap

[Mr.SWISS]

Possibly subframe bushings...

So is it normal for my RSFB to come out about 1/2" when I lift the car? I am trying to track down my thump and have replaced the RSM'S, Axles are brand new, drive shaft has a fresh CSB and guibo done at time of swap, and the diff was swapped for a LSD out of an auto 535is. I didn't notice it until I got the new diff in and there is 0 play in the shaft and minimal from the ds input to the axle.

[Brew]

Possibly subframe bushings...

[PiercedE30]

maybe CSB....could be a soft rubber in the csb itself that gets warmed up and loosens up as the exhaust piping warms, this would allow it to flex some and giving you some play in the driveline.

[static]

Hi crew

For some time i thought that this was due to me having ltw flywheel, but now a buddy of mine chimed in mentioning he's got exactly the same problem on his s52 swapped e30, and connecting link is that it was the same mechanic who did both of our conversions. (he is a great bmw mechanic though and been around bimmers forever)
He has a normal stock heavy flywheel and we both have ZF tranny.

Here is how to reproduce the problem: when the car is warmed up, go in 1st gear, give a bit of gas, then lift for like a half second, then push clutch all the way in - the result is a series of dull clunks/thumps with reducing loudness. If I skip the half-second accel lift before pushing clutch in, the clunk is not there (so i guess it is directly influenced by the load on the driveline)

So my question is: what could that be possibly caused by?


Alex