Persistent Steering Wheel & Car Vibration at Highway Speeds (E85 Z4)

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Datoshkae

Member
Hey guys, a long time lurker but a new member :)

Hoping some of you experienced owners might be able to shed some light on a persistent steering wheel vibration issue I've been battling with my E85 for the past couple of months. It initially started as a noticeable shake around 55mph, only really making its presence known at highway speeds.

Naturally, I jumped into troubleshooting mode to try and nail down the culprit. Here's a rundown of everything I've done so far:

1. Alignment and Bushing Replacement:
My first thought was an alignment issue, so I got a full alignment done. While at it, I also had some worn bushes replaced in the front suspension. This actually seemed to improve things slightly, but a noticeable vibration was still present (and I know Z4s can have a firmer ride, but this felt beyond that).

2. Replaced all my tyres:
These needed a change anyway but with this out the way i confirmed that it's not an imbalance or bulges in the tyres. They're the nice ones too (Michelin & Continental) - I also have the pressure to spec.

3. Wheel Balancing and Buckled Wheel Replacement:
Next up, I had all my wheels balanced. Unfortunately, one of my wheels turned out to be buckled, so I went ahead and replaced it with a new one, which was also balanced. I was really hoping this would be the end of it!

4. Brake Discs Replaced (Separate Issue):
I also noticed a wobble in the steering wheel specifically when braking. To address this, I replaced my brake discs, and thankfully, that particular issue is now resolved.

5. Wheel Refurbishment and Loaner Wheels:
Thinking maybe there was still an issue with my original wheels, I recently had all four of them professionally refurbished and powder-coated. During this time, I had to drive on a set of loaner wheels, and surprisingly, the vibration issue was actually worse with the loaners than with my original setup! After getting my refurbished wheels back and fitted (and presumably balanced again by the tyre shop), the steering wheel vibration is still there. In fact, it now seems to occur across a broader speed range, roughly between 45mph and 70mph, with it being most prominent around 60mph.

6. Bearing and Tie Rod Check:
I even tried to check the wheel bearings myself by giving each wheel a spin and a firm tug, and I didn't notice any abnormal noises or obvious play. Similarly, I had a look at the tie rods, and they seem to be in good condition with no noticeable looseness

So, here I am, still experiencing this frustrating steering wheel vibration, and I'm completely stumped on what the cause could be. I've thrown quite a bit at it already, and the fact that the loaner wheels made it worse is particularly confusing.

Has anyone else experienced a similar persistent vibration after going through these steps? Any thoughts on what I might be missing or what I should investigate next? Any advice or shared experiences would be hugely appreciated as I'm starting to run out of ideas!

Thanks in advance for your help!
 
You say 'some worn bushes' replaced at the front.
Do you know which ones, and more importantly, which ones were not done?
 
Thanks for the replies!

When going for the alignment the garage said I had to change the control arm bushes - pretty much nothing else was done recently.

Interesting advice on the seized brake callipers. I didn't think of that since i didn't feel any resistance in the wheels. I will check them this evening.
 
Datoshkae said:
When going for the alignment the garage said I had to change the control arm bushes - pretty much nothing else was done recently.
Click to expand...
So the ones at the rear of the front wishbones? Known colloquially as lollipop bushes?
Are you sure there is no play in the other two mounting points on the front wishbones, particularly the inner joint that bolts to the crossmember.
 
Easy to check for a seized caliper, the affected wheel will be baking hot after a drive. If you don’t have an excessively hot wheel, then you’re unlikely to have a seized caliper.
 
Apologies guys for the late response - I had a run-in with the BMW garage.

Callipers all good. Consistent temperature both sides on the front, same for the rear.
Yes I replaced the lollipop bushes, whilst that was being done all other bushes were checked by the garage and found to be good.

I realised I did not mention a crucial point; Spacers. Car came with them on, I should've checked. I've ordered a set of shorter bolts so I can test the car without spacers on at spec - should arrive Tuesday.

Had a bollocking from the BMW Service mechanic today that I had the wrong alloys on, had me to go to Parts dept to find the right ones - turns out mine are the correct ones. Seems like a reluctance to touch an older car - bit ageist - may go to another dealer/specialist if I can't find the fault after Tues.
 
You need to jack it up and try spinning the wheels by hand. It wont be fully seized (if that's the problem), just enough to cause issues and to not make the wheel unduly hot.
 
Gotcha, I gave it go this morning. All four appear to be fine with the calippers.

I removed the spacers on all the alloys, the wobble is not as bad but it is still present.
 
The spacers likely did accentuate the problem, I removed them and have felt a difference.

I realise now why there are spacers on the car (installed by prev owner); the rear alloys are actually the same as the front. They're supposed to be alloys that are already staggered... My guess is the previous owner didn't know and staggered them anyway. Also the tyres aren't to spec so I've changed that too.

After a road force balance I've managed to significantly reduce the shaking. There's still some shake and that's likely due to a buckle (driver front & passenger back) so will look to remedy that too.
 
Out of interest, what wheels are you running. The 17” wheels which were fitted as standard across most E85 models were not staggered (all 8”x17”), whereas the upgrades were all staggered (8”x18” and 8.5”x18”), so this shouldn’t be a factor.
You may also have a failing wheel bearing, which you might be able to detect by spinning the wheel, or a poorly fitted wheel bearing, which you probably won’t.
If you have a buckled wheel which the garage hasn’t spotted, then shame on them.
 
It's the later case for me. I have:

all four are 8J X 18H2 IS47 - 135M Sport MV2 10 Double Spoke 18″ inch (36117896470)
‎ ‎‎When going to BMW they said the rears need to be 8.5J X 18H2 IS50 (36117896490) when running with the above wheels at the front.
The buckle was only finally spotted when doing the road force balance recently, so yes it's a shame no other garage could spot that.

I did give the wheels a spin to check for bearings, i did have an issue in my prev e85 (2.0i) so I know what to look for but cannot find it :/
 
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