knock/clonk off side rear

[abelai]

Car is a 325i sport (LSD), has poly subframe bushes (soon to be replaced with standard BMW rubber), STA bushes also poly, Bilstein b12 suspension, top mounts new BMW, new spring pads , z3 m diff mount also new prop coupling and new BMW standard 2 part exhaust with all new mountings. Boot is empty.

The car makes the knocking sound when pulling off forward and reversing, passenger has confirmed sound is rear drivers side. You can not replicate sound or any noise by bouncing the car while stationary handbrake on or in gear handbrake off. Noise car be replicated trying to reverse or move forward with handbrake firmly on. Knocking can also be heard while going round tight right handers slow second gear but not normally left.

Droplinks and ARB Bushes are old but not broken.

Fire away if you have a idea of what is causing this.

[abelai]

Could the diff or driveshfts/cv joints cause the noise. If so what's the best way to check them?

[blingsta]

the diff itself ??

[dazleeds]

shocker top mounts?

[abelai]

shocker top mounts?

Can't replicate via bouncing rear, boot carpet is out and top mount not moving.

[abelai]

the diff itself ??

How do you test/inspect play in crown wheels, bearings ect?

[abelai]

Ok I have just had another look under the car both wheels jacked up, if I rotate the prop the diff output flanges start turning instantly so I assume for the time being the diff to be good, but there is rotational play in the inner and outer cv joints, looks like more on the o/s than the n/s. Also with the car on the ground i can feel(not see) slight movement (front to rear of the car) by pulling on the o/s driveshaft but not the n/s.

How much play is acceptable in a driveshafts cv joints or am I barking up the wrong tree?

[Bob_S]

I would be tempted to say this is your problem, jack the car up with the handbrake on and try rotating the driftshaft to and fro see if you an replicate the noise.

[abelai]

It does sound similar but I'm hearing it from a totally different position, outside under the rear of the car. Just worried about convincing myself that this is the problem changing the driveshaft (which is a bit of a pain and not cheap for a new one) and it still isn't fixed.

So if somebody can tell me there should be no visible rotational play in the cv joints I'll do it.

[abelai]

Have done alot of google searching, I have come to the conclusion my cv joint is fubard.

Are the GSF driveshafts any good, has anybody here ever replaced a driveshaft because of the cv joints? Not sure if second hand would be the way to go 20 year old parts and all that.

[Bob_S]

I have replaced one from my stock pile, was fine.

[abelai]

I have just picked up a new driveshaft from GSF and there is no rotational play what so ever in it, so mine is deffinately worn. Whether this will stop the knocking is yet to be seen(heard).

I have been thinking about this and wondering if the lsd causes more wear on the cv joints?

Shall keep you all posted.

[bmw9818]

Did new shafts stop clunking...?

[abelai]

Not really, but when I ditched the subframe poly bushes and went back to genuine BMW rubber my problems went away.

[appletree]

Not really, but when I ditched the subframe poly bushes and went back to genuine BMW rubber my problems went away.

Hi, i have the exact same noise and all my bushes aren't old atall!

you say not realy, do you mean it made a bit of a differance or no differance atall?

Also did you only change the subframe bushes when you got rid of the noise or did you find anything else of note while you were working on it.

[bmw9818]

After I've put void fillers in knocking stopped on mine...

[appletree]

i do have some void fillers i never fitted, might try that first. Thanks