Rear-end clunks

B

boz

Member
 London
Hey, I was hoping someone could point me in the right direction as this has been driving me a bit mad.

A few months ago, my Z4MR developed clunks somewhere at the back. It would only happen when I corner and never in a straight line when I went over bumps.

Naturally I thought it was either the springs or the rear shock mounts and got them both replaced today. The RSMs were a bit knackered but the stock springs that were removed were absolutely fine (I was going to replace them for the eibach ones at some point anyway so i wouldn't have to deal with the typical snapped springs). Driving out of the garage, the knock was still there. The mechanics noticed it too but didn't really have an idea of what it could be without further investigation. The suspension is completely fine :?

Does anyone have any idea what else it could potentially be? :(

Thanks in advance!
 
Wild guess. Only when cornering could point to a diff problem, especially if suspension checks out. Consider changing the fluid?
 
Thanks for the pointers but I'm not that mechnically minded :s

@claymore - The car has done 27k. What's a flex disc/guibo?

@beedub - rtabs?

@bcworkz - the diff was going to be the next thing the garage would look at...
 
Take it that it happens when cornering both ways? Couldn't be something loose in the battery tray or even in the centre cubby bin? Sounds like a real mystery.
 
boz said:
What's a flex disc/guibo?
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Rubber/metal flexible disc that fits between two parts of the transmission that reduces vibration/shunt - #2 in the following photo...
367.png

boz said:
rtabs?
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Rear trailing arm bushes - the bushes (part #4) attached to part #1 in the following diagram...
227.png
 
I've already been through the boot and taken out pretty much everything to see if that was rattling around. I did recently change my battery so maybe I will check how tightly it's held again.

Thanks for the explanation and diagrams mmm-five :)
 
boz said:
I've already been through the boot and taken out pretty much everything to see if that was rattling around. I did recently change my battery so maybe I will check how tightly it's held again.

Thanks for the explanation and diagrams mmm-five :)
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thats a good point actually when you changed the battery did you use the furtherest in bolt in location, their are 2, one bolt location closer to the rear, one futher in, the furthest away battery bolt in location is for bmws that use the much bigger batteries, this will allow you smaller batt to shift backwards and forwards...... just a thought due to you changing the battery recently...
 
Just had a poke around and the battery is in tight - no moving around at all :/

Guess I will have to get the car back to the garage next week...
 
Took the car in today and the results weren't what I was expecting.

According to the garage, there wasn't anything wrong. They took the back of the car apart, tightened up all the bolts and the clunks were gone :)

Mystery over!
 
boz said:
Took the car in today and the results weren't what I was expecting.

According to the garage, there wasn't anything wrong. They took the back of the car apart, tightened up all the bolts and the clunks were gone :)

Mystery over!
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Interesting, I hope mine turns out this way (3.0 coupe)
 
Not sure how one removes the boot! I can't tell you how may times I took something apart, found nothing wrong, reassembled, and - voila - problem gone. Glad it's sorted!
 
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