Is this normal noise for rear halfshafts? (video)

[evilnickwong]

My E30 has been having a clunking noise from the rear, mostly left side everytime I go over potholes or really bumpy road.Trailing arm and subframe bushings were replaced less than 8,000km/2 years ago. Rear shock mounts replaced last year with Fabian's PU version. Diff bushing replaced a month ago.Then yesterday I was looking under the car and noticed my half shafts make a knocking noise when I rock them side to side by hand. Is this normal?[video=youtube;Lo2JCr1DnNM]http-~~-//www.youtube.com/watch?v=Lo2JCr1DnNM[/video]Some folk on r3v commented that my subframe bushings are weird, because of the space between the subframe and body:

But I asked my mechanic and he said they look fine.

 

[pussy]

ha !

first thing, the drive shaft too loose... not supposed to move that much.

second thing, your subframe bush looks like koyak inside..to check, stand on the rear door sill and rock the rear... the noise should be evident...


cheers...

 

[evilnickwong]

hi felix
so for the drive shaft, can it be repaired or I have to source a replacement?
still possible to source new half shaft or can it be refurbished?

I stood on my rear sill to shake the chassis up and down before, I get alot of creaking squeaking noise, but I don't think I hear the clunk from doing that
how come you say the subframe looks koyak? it's only < 8000km old, I thought these bushings suppsoed to be 30,000 km or something. -.-

 

[pussy]

hi Nick..

the drive shaft is too loose to be repaired, somemore your driveshafts is the 318 ones, hence it's weeker type.. try looking for a 325i ones.. better and more weight distirbution to the rear.. repairing will not cure this problem, since you getting a second hand one put it in then once a month has gone by, get the boot shafts replaced and gear greased up... this will last you for years...

the subframe bush and distance from the top is too far.. i wander why ? not pump in fully or the bolt loose ? the creaking noise is the handbrake drum noise..
bushings can even tear less than a month also...


cheers...

 

[evilnickwong]

OK, so sourcing for 325 half shafts is best. Why wait for a month before replacing the boots and regreasing? To make sure nothing serious wrong with the used units?

I suspected the bolt was loose, but my mech tightened it again, still the same. I thought the distance between subframe and body was due to the neck in the bushing itself.

So, the clunking is because of the half shafts or the subframe mounts?

Thanks!

 

[pussy]

yes, wait for month...cos of any sound or warranty claim from the chop shop..

yup , the bush looks low too...some thing not right...

 

[evilnickwong]

ok understood. will try to look for 325 units and see. and also check out the rear shock mounts.

btw, is the clunking more likely to be from the half shafts or from the subframe?

 

[moots]

howdy nick,
my suggestion is to get a new mechanic.in no way is your LH subframe bushing ok!there shud not be any gap there.the bushing shud fit snugly in the subframe and the whole subframe fitted straight to the car.

the half shaft,by design,must have some axial play to take up the horizontal movement of the suspension.i doubt that's the cause of the knock.

have your subframe bush looked at asap as this cud be dangerous as more than 70% of the rear suspension components are conected to the rear subframe.

 

[evilnickwong]

can someone with an e30 take a photo of their subframe bushing from the same angle I did? I'm curious to see what it should really look like and I can't find any photos online

moots: ya the half shaft should have axial play, however, should it have that knocking noise when I move it around as in the video? that's what led me to think that everytime the half shaft is compressed from horizontal movement, it will have that same knocking noise

 

[moots]

yes if you force the half shaft that way it will exhibit that noise but under normal drives there will not be any forces acting on the half shaft to make it move that way.

attached is the closest that i have snapped on my previous e34....does not help much does it but believe me the gap shhud not be there as i have DIY my subframe bushes(on my e30) myself .

 

[evilnickwong]

So, an update finally after a long while. First thing, I tried pussy's suggestion of standing on the rear door sill and bouncing the car. I took a video from underneath. Bouncing the car like this did not produce the clunking sound and from the video, the subframe bushing doesn't seem loose or anything. Of course, the force of me bouncing it is probably much less compared to when the car hits an uneven stretch of tarmac.

[video=youtube;qPe7Y4_JT2Y]http://www.youtube.com/watch?v=qPe7Y4_JT2Y[/video]

So next thing, went to my mechanic to remove my rear shocks and inspect the aftermarket PU rear top mounts, in case they were faulty. They were fine.

However, noticed a few things about my rear absorbers, both of which are Bilstein blacks, replaced about 2 years ago.

The bottom mount seems to have become very worn, the metal sleeve appears deformed or enlarged as you can see:

Also, the rubber around the bottom mount is cracked.

Additionally, when I compress the rear shocks, they return to full position a bit slowly, but more importantly, I can feel or hear a very slight grinding as it moves back to the normal state.

Would worn rear absorbers (+ that funky looking bottom mount metal sleeve) be a cause for clunking? Certainly seems possible...

 

[evilnickwong]

No feedback from anyone? :-/

 

[moots]

nick,the subframe bushing gap....are they the same for both lh and rh?is the other side also showing the same gap per the first pic?

 

[evilnickwong]

moots: Yeah both sides look the same. Had 2 different mechanics (both of whom I have had no issues with in the past) say that they look normal.

Any comments on the condition of the bottom mounts of my rear shocks? haha

 

[moots]

the rubber bushings on yr shocks are cracked and that's all there is to it.it is still useable.the metal sleeve also no issue.
back to the rear subframe bushes.the gap is not supposed to be there!

gud luck

 

[evilnickwong]

Hmm OK. Perhaps I'll bring it to Optimum for a third opinion then when I'm back for Christmas break.

 

[pussy]

aiya... you got my number, call me or moots to meet up, show us the car, then we can help you. on the forum quite hard to tell.

 

[evilnickwong]

Haha OK will do when I'm back for Christmas break soon.
I'm in Singapore most of the time mar, usually only come back for short weekends here and there.