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Uneven rear suspension

Discuss problems you have had or are having with your Z4
Chris1981
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 9:00 am

So after realising my car was sitting way too high in the rear... suspecting that someone had fitted incorrect springs when the original ones snapped, I bought a set of H&R lowering springs as all 4 cost me the price of 2 new rears and I'd get nice new fronts too!

However the car now sits uneven at the rear and is noticeably lower on the drivers side and it's very annoying! I've had the car up a few times since and ensured springs are orientated the same and seated correctly but I can't get rid of this uneven height!

I've read that 'they all do this...' on a few forums, that it's due to the car being designed as LHD so there is a weight imbalance to counteract the driver's weight but I'm not sure about that, does anyone else on here suffer with uneven rear ride height?

Worth noting I'm still on standard shocks if that has any bearing, I do plan on replacing them but want to sort this ride height issue before I go spending more money! I also think it was uneven before I lowered it and hoped that new springs would resolve it... they didn't!

Any assistance on where to look next or what may be causing the height difference would be greatly appreciated? Does anyone else suffer with uneven rear ride height?

Car is an e86, 3.0si Sport Coupe
E86 Coupe 3.0si Sport - Montego Blue, Pearl Grey with Piano Black dash
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Uneven rear suspension

Post by markplant » Mon Jul 24, 2017 9:27 am

I'm sure there's meant to be a rubber pad that the spring sits on are they all in place, does the strut tube have signs of oil leaking, on the side that's lower, before you did anything, other than it been high was it level
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Chris1981
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 10:07 am

Yes both spring pads are in place, I've even made sure they are aligned the same too in case there's any difference in the thickness of the material as they aren't round.

No signs of leak, I've only had them disconnected at the bottom but I would think any leak would make it's way down there pretty quick!

I'm not too sure if it was even or not before changing the springs but part of me thinks it was uneven then too!

Would a weak shock absorber cause uneven ride height? as it's the drivers side I would think it has a lot more wear than the passenger!? I could swap them over and see if the issue moves sides I guess....

Would worn bushes affect ride height?
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BC BR series Coilovers, powerflex bushes, 15mm spacers, Custom SS exhaust, CDV delete

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Uneven rear suspension

Post by jamie_z4 » Mon Jul 24, 2017 10:09 am

you can get different thickness in spring pads from the dealer. they vary from about 3 mil to about 15mil depending how far its out , not a great fix but thats what its like on E46s too.
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 10:39 am

That could be an option, cheers Jamie!

Think I'll start swapping components from one side to the other and see if that does anything... if it's spring or shock related then I would think the uneveness will switch sides and the passenger side will sit lower!?
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Uneven rear suspension

Post by jamie_z4 » Mon Jul 24, 2017 10:53 am

yea think the shocks n springs wont do anything mate. always worth a try tho, have you checked the Anti roll bar drop links are both connected?
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 11:04 am

Fair do's... saves me the effort, cheers mate!

Will check the antiroll bar but would have though I'd have all sorts of problems if it was disconnected at one end!?
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Uneven rear suspension

Post by jamie_z4 » Mon Jul 24, 2017 11:33 am

not nesescarily mate- my front droplink had totally come out of the bal and socket and only time i noticed was a long sweeping bend coming off the motorway - iit looked like it'd been off for weeks
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 2:14 pm

I recall there being enough resistance when fitting the new springs in to make me think the bar was connected correctly but will defo check it out tonight!
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Uneven rear suspension

Post by Ewazix » Mon Jul 24, 2017 2:35 pm

The LHD thing is an urban myth. The springs are not handed Left or Right, the spring pads are the same L/R, besides which fuel weight and having a passenger would make the differences redundant. Some wheel alignment operators will adjust alignments slightly to take account of left or right hand road camber but this wouldn't affect ride heights. BMW TIS ride height spec's make no mention of L/R height differences.

If you call up TIS for your car it will give you the ride height range including permissible variation (which is more than you might expect).

There are lots of factors that make one side/corner sit lower, including wear and structure drooping due to loose strut braces or braces re-torqued whilst jacked up or not on a dead flat surface (or accident damage), also possibly damaged bushes or arms etc, but taking account of tubby Germans isn't one of them :wink:
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Chris1981
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Uneven rear suspension

Post by Chris1981 » Mon Jul 24, 2017 2:57 pm

Yeah I don't buy the whole LHD argument either! The theory of tolerances could explain this issue, it's about 10-20mm difference so if a tolerance of +/-10mm could give a theoretical difference of up to 20mm so will look into BMWTIS and see what it says!

I'll be checking out the ARB tonight so will take some measurements to be sure!

Thanks for the advice so far... be interested to know if any other forum members suffer from uneven rear ride height too!?
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Uneven rear suspension

Post by jamie_z4 » Mon Jul 24, 2017 2:58 pm

Ewazix wrote: Mon Jul 24, 2017 2:35 pm the spring pads are the same L/R, besides which fuel weight and
they aren't. see above, you can get different thicknesses from BMW to compensate.
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Uneven rear suspension

Post by Ewazix » Mon Jul 24, 2017 5:21 pm

jamie_z4 wrote: Mon Jul 24, 2017 2:58 pm
Ewazix wrote: Mon Jul 24, 2017 2:35 pm the spring pads are the same L/R, besides which fuel weight and
they aren't. see above, you can get different thicknesses from BMW to compensate.
I know you can get different thickness pads to adjust anomalies but that's not the same thing as BMW setting the cars up deliberately 'wonky' for left hookers and not bothering for the UK market, that's an urban myth.

Again, there is nothing in TIS to suggest that different thicknesses are fitted L/R according to which side of the road the car is designed for. I've had my rear suspension off and when I checked them for condition they were the originals and the same thickness, until someone comes up with an authoritative source for the wonky LHD set-up theory I can't see any reason to believe in it 8)
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Uneven rear suspension

Post by jamie_z4 » Mon Jul 24, 2017 6:54 pm

Ewazix wrote: Mon Jul 24, 2017 5:21 pm
jamie_z4 wrote: Mon Jul 24, 2017 2:58 pm
Ewazix wrote: Mon Jul 24, 2017 2:35 pm the spring pads are the same L/R, besides which fuel weight and
they aren't. see above, you can get different thicknesses from BMW to compensate.
I know you can get different thickness pads to adjust anomalies but that's not the same thing as BMW setting the cars up deliberately 'wonky' for left hookers and not bothering for the UK market, that's an urban myth.

Again, there is nothing in TIS to suggest that different thicknesses are fitted L/R according to which side of the road the car is designed for. I've had my rear suspension off and when I checked them for condition they were the originals and the same thickness, until someone comes up with an authoritative source for the wonky LHD set-up theory I can't see any reason to believe in it 8)
Fair enough. Just saying there is a solution relatively cheaply available from bmw the selves so if they endorse it it must be feasible solution for the op
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Uneven rear suspension

Post by Steve84N » Tue Jul 25, 2017 8:22 am

My money would still be on the spring not being quite seated properly. I had difficulty with this as it looks on but when you check the distance between the edges of the arm it was out. You can also feel under the pad if it's seated over the node.
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