clunk/thump when pushing clutch at low speeds

[davem]

well had some additional opinions and it looks like it's play in the diff... really weird considering the diff was in a babied automatic car with 119k miles. I doubt I will go through the trouble of dropping it and fucking around with it so it I guess I gotta live with it... :/

[davem]

Flywheel loose?

out of ideas at this point :P !!! check for random bolts that are not 100% tight??

haha I am pretty scared it's something like this...

[Wanganstyle]

Flywheel loose?

out of ideas at this point :P !!! check for random bolts that are not 100% tight??

[davem]

if you want to test this, just add extra revs and let out the clutch very slowly (basically engage and burn clutch a bit). A very gentle clutch meetup would overcome uneven flywheel surface; as long as clutch is engaged there should be no more clunking noises. if you flywheel was very imbalanced it could cause some vibration, but not really clunking/thumping.

have you checked the U joints in the driveshaft? those items wear over time and are hard to diagnose

bro read my post on the first page lol - the clunk is when i disengage the clutch at low rpms and it doesn't clunk when I disengage at higher rpms... also I already mentioned that I replaced the driveshaft with a rebuilt one because I kept reading about the failed u-joints... you can imagine my frustration when I did the swap on jack stands and it didn't fix anything haha

[Wanganstyle]

A buddy of mine thinks it may be my flywheel not having a perfectly flat surface. The wheel was not resurfaced before it went in my car because it appeared to be in very good shape. Makes sense to me due to the symptoms changing depending on how fast the engine is spinning.

if you want to test this, just add extra revs and let out the clutch very slowly (basically engage and burn clutch a bit). A very gentle clutch meetup would overcome uneven flywheel surface; as long as clutch is engaged there should be no more clunking noises. if you flywheel was very imbalanced it could cause some vibration, but not really clunking/thumping.

have you checked the U joints in the driveshaft? those items wear over time and are hard to diagnose

[davem]

A buddy of mine thinks it may be my flywheel not having a perfectly flat surface. The wheel was not resurfaced before it went in my car because it appeared to be in very good shape. Makes sense to me due to the symptoms changing depending on how fast the engine is spinning.

[davem]

pretty strange. differential i couldn't imagine being the cause since its 2 for 2 cars. what mounts did your mechanic use?

everything is OEM rubber Lemforder/Sachs/Febi

[Unearth078]

ya all the bushing in my rear end are new

pretty strange. differential i couldn't imagine being the cause since its 2 for 2 cars. what mounts did your mechanic use?

[davem]

ya all the bushing in my rear end are new

[Unearth078]

this was cause by my diff bushing i think. rebuilding the entire rear solved the issue. this included new poly everything though. i could see why people would believe it to be rsfb's

[davem]

TIS is the BMW internal service guide, i think somewhere on rev is a good link to this. there is entire diff service manual there :)

you kept your original Auto diff when you swapped? if so the 4.10 gear ratio is going to add torque to ground and make any play in the driveline felt even more noticable.

with a S52 swap and its ZF trans +4.10 your 5 gears become short as all hell.
with s52 swap and G260 e30 5 speed and the 4.10 auto diff the gears are still quite quite short.

if a random diff with lower gearing ratio was fitted, was it checked before install?

In my second post I mentioned that I didn't realize that this thread was originally posted in the 24v section, I searched, found this thread and bumped it without noticing lol. I have an m20.

The diff in my car is the original one and it is an 373 LSD. Apparently Canadian market cars got the 373 with the automatic as well.

[Wanganstyle]

TIS is the BMW internal service guide, i think somewhere on rev is a good link to this. there is entire diff service manual there :)

you kept your original Auto diff when you swapped? if so the 4.10 gear ratio is going to add torque to ground and make any play in the driveline felt even more noticable.

with a S52 swap and its ZF trans +4.10 your 5 gears become short as all hell.
with s52 swap and G260 e30 5 speed and the 4.10 auto diff the gears are still quite quite short.

if a random diff with lower gearing ratio was fitted, was it checked before install?

[davem]

having a clutch and flywheel is more jolting than the gentle lock up of a OEM torque convertor.

easy way to see:

put rear of car in air. turn either driveshaft or one of the wheels and see how much play/slop there is before the ring and pinion engage. Open diffs will have tires spin opposite and show the play of the gears directly, LSD cars will show gear play and LSD unit lock up play if you give it some rotational speed (and the tires mass)

E28/e30 era diffs are very old; although the ring and pinion units are same as any 188mm and can stand alot of power, the items wear over time and should be re-set to prevent excessive play. You can reference the e30 OEM BMW TIS on this procedure :)

hmmm that's odd, my car only has about 190k kms (118k kms). What is this procedure called and what is the TIS? The Bentley manual doesn't appear to touch on this subject.

[Wanganstyle]

having a clutch and flywheel is more jolting than the gentle lock up of a OEM torque convertor.

easy way to see:

put rear of car in air. turn either driveshaft or one of the wheels and see how much play/slop there is before the ring and pinion engage. Open diffs will have tires spin opposite and show the play of the gears directly, LSD cars will show gear play and LSD unit lock up play if you give it some rotational speed (and the tires mass)

E28/e30 era diffs are very old; although the ring and pinion units are same as any 188mm and can stand alot of power, the items wear over time and should be re-set to prevent excessive play. You can reference the e30 OEM BMW TIS on this procedure :)

[Balleristic31]

My diff clunks like no other. And since u said it didn't do it until u swapped diffs... I'd check there.