Coil springs knocking sounds

[JakeS76]

I had both rear coil springs replaced recently as one had cracked. I've noticed a knocking sound occasionally since. First of all I thought it was my large can of tyre weld rolling around in the boot. But I cleared out the boot and still get the occasional noise. It's from one side or the other not both sides at once , on the rear where the springs were replaced.Looking at other posts on the forum I think it's probably the spring pinching the rubber? And the suggested solution is to remove the springs, cover with talc? And then refit but 1/4 turn anti clockwise.

The car is booked back in the garage in 4 days but do you reckon it would be ok to still drive it in the meantime? Or is this likely to damage the suspension?

 

[B21]

Its just annoying..no damage will ensue..BMW issued a service note about this..assuming its that specifc issue

 

[JakeS76]

Thanks . Have you got a link to the BMW service note?

 

[flybobbie]

Yes my post years ago. I took out washed the rubbers, talc and refitted.
Right rear spring by chance ended up rotated 45 degrees forward of it correct posn. Lettering S21 should be outboard, but ended up 45 degrees forward anti clockwise.
Sound was like a rubber mallet hitting bottom of boot.
No noise now some 11 odd years.

 

[JakeS76]

Thanks. I'm pasting a link to your original post to help anyone else with the same issue. https://z4-forum.com/forum/viewtopic.php?t=129915

 

[JakeS76]

On the BMW fix that you found, it mentions putting the car on a lift so the wheels hang down. Then cleaning the upper coils and rubber mounts with a dry rag. Before applying talcum powder. Is it possible to see if the S21 lettering is facing outboard without removing the springs?
If the lettering is facing the correct way I guess the garage should be able to do this without removing and refitting the coil springs?

 

[Busterboo]

(As I posted at the time.)

The springs also break. Cheap to replace. 30 minutes labour + part. Less than £100 each at an independent.

Also easy check for breakage. On flat surface, measure top of each rear wheel arch.

 

[flybobbie]

Wheel off you can see the S1. (not S21, was 10 years ago, memory going).
I had to remove bottom bolt of shock absorber, detach bolt of anti roll bar and lever down the suspension arm.
Spring can be pulled out or just rotated.
Right spring.

I think barrel spring allows same effect as much long straight coil spring.
Only problem i think is the ends rotate on compression clamping on the rubbers, then rebound.
Also load not vertical.
Crap really.

 

[Busterboo]

Crap really.

True.

 

[mcbutler]

Just change the rubber seats dont arse around with talcum powder it'll only wash right off.
When i upgraded my 35 rears at 30k miles one of the rubber seats had worn through - talcum powder wont fix that
Seats are cheap and easy to fit

 

[JakeS76]

The car was back at the garage yesterday for them.to.try and fix the problem. I took in the forum members recommendations with the BMW suggested fix. They turned the new coil springs so that the lettering/numbering faced outboard. And cleaned them before using a specialist auto grease. That they told me would be fine on the springs and rubber mounts.

Like you, they thought that talc would wash off so didn't use that.
I didn't get your post in time to ask them to change the rubbers. But hopefully won't need to do this now. But it's good to know.
The old springs didn't make a knocking noise. I only had them replaced as one broke going over a pothole on the way to the MOT test.
The car seems ok now.

 

[flybobbie]

I think the talc idea was just a quick lazy fix suggestion by BMW to dealers.

 

[Five-O]

I tried the talc fix today as both the rear springs have been knocking since I changed them a few months ago.
So far after a 12 mile test drive it's solved the issue although I don't hold much hope for it. Seems a bit of a bodge really.
If it does fail are these the best spring pads to get?
https://floflex.co.uk/product/bmw-3-series-z4-compact-rear-rear-spring-pads-upper-lower/

 

[noz85]

We had both our rear coils swapped as they were snapped at the bottom, and the rubber seats replaced top and bottom on both, but there was still a knocking sound.

Turned out both rear anti roll bars had sheered and had to be replaced. It resolved the knocking. Might be worth checking.

 

[Five-O]

The talc bodge didn't last for long.
Does anyone know where to get these pads from?
Everywhere I've checked lists them for e85's but not e89's.

 

[noz85]

The talc bodge didn't last for long.
Does anyone know where to get these pads from?
Everywhere I've checked lists them for e85's but not e89's.

For our E89 2016 i got exactly these ones and they're fine.

https://www.lllparts.co.uk/search/33531094518

https://www.lllparts.co.uk/search/33531136385