Z4M steering wobble

G

gallj

Member
Hi all, firstly to introduce myself - i've owned several BMW's over the years including motorbikes & have recently got my hands on a Z4MC.

Absolutely love the look of it, handling & most of all the engine note, however, anytime i go over a bump or imperfection in the road at any speed the steering wobbles. What i mean by wobble is a judder from left to right which when holding firmly on the steering wheel isn't all that bad but when loosely holding the wheel it physically moves in your hands.

I've checked the obvious things (ball joints, bushes, control arm lollipops, inner & outer tie rods, shocks etc) & have also had the wheel balance checked & the rims checked for any runout but everything checks out fine. Hunter alignment has also recently been done.

I should also note that the car has had a recent MOT (no advisories) & also has FBMWSH.

Maybe its just the sensitivity of the hydraulic steering but should it be that sensitive to bumps in the road?

Bit stumped with this one so hopefully someone on the forum might have some ideas?

Cheers
 
Hi. Congratulations on your purchase. As you suspect I would definitely say what you are describing is not normal. Alas, it sounds like you've checked obvious culprits and I can be of no more help. Certainly though the steering as you describe should not be like that. Whereabouts in the country are you? Have you taken it to any kind of indy specialist? I'm sure we could all recommend a few.
Best of luck with it.
 
Thanks for your response. Im up in the north east of Scotland & have taken it to the local BMW dealer who reckoned control arm bushes but after inspecting said they were fine & could see nothing wrong. After this I then re checked everything again myself & all seems normal.

Only thing I could think of is possibly the steering rack but the cars only done 40k miles & there are no leaks in the system etc
 
Not my part of town so can't help on location, but I would suggest getting it to an m3 or bmw specialist of sorts for their opinion. They will often have more ideas and experience on these cars than many Bmw dealers to which these are old cars.
 
hi chap,

what camber setting do you have on your fronts (or rears for that matter)?

are the roads you drive on quite cambered/crowned?

These factors can have a serious effect notwithstanding the lack of a mechanical problem. What about the motorway - how does that work?

I suppose, given your location, you might tell me to go take a hike (pun fully intended) if you're not a huge mototrway user.

If your roads are totes flat and your steering is dodgy, you have a problem. :!:

Stevo
 
I don't have an M, but I had a similar issue a little while ago.
When it was in for a service they changed my bushes as well and the wobble you mention has 100% gone.

I know you said you checked them already, but replacing mine fixed it.
 
Thanks for the reply's so far. This morning i got the car back up on the jack stands & got the pry bar out again - there is the slightest amount of play (like 2-3mm) in one of the bushes on the passenger side control arm. That being said the amount of force I was using was quite heavy.

I would have expected this to be normal as there surely needs to be a small amount of play in any bush for it to operate correctly?

Is this normal or should there be absolutely zero play?

Thanks in advance
 
gallj said:
Thanks for the reply's so far. This morning i got the car back up on the jack stands & got the pry bar out again - there is the slightest amount of play (like 2-3mm) in one of the bushes on the passenger side control arm. That being said the amount of force I was using was quite heavy.

I would have expected this to be normal as there surely needs to be a small amount of play in any bush for it to operate correctly?

Is this normal or should there be absolutely zero play?

Thanks in advance
Click to expand...

Had a similar issue when I bought mine. Although to be exact the steering wheel wobble can be described as oscillation when the steering wheel moved from left to right ever so slightly. After checking all of the above,

Balancing,
Bushes and other suspension parts
Wheel / tyre condition - as tyres can be faulty or become faulty!

Turned out there was a small about over overspray when the wheel was refurbished. Actually it was probably a lump of paint! so the wheels looked to balance ok but obviously not when on the car.

In regards to the bushes, the chap who worked on the car mentioned that the bushes are rock solid and if they were dud they would show. BMW Warranty work by the way...
 
One thing I did forget to mention is I tried a set of winter wheels on the car to rule out tyres, alloys etc & the problem was still there.

It's not as if it's a balancing issue as even if I'm crawling at a snails pace on a bumpy road the steering wheel wobbles.

Does rock solid mean absolutely zero play?

Also, is it possible that a bush/ball joint may be knackered if on visual/pry bar inspection it appears ok?
 
Hi all,

Just incase anyone had the same / similar problem or is interested, this was finally traced to the top mounts being at fault on both sides. Replaced both & no more wheel wobble.

There was around 1/2" of play when levering the tyre upwards which would have allowed around the same amount of play side to side, hence allowing the suspension geometry to change when going over a bump & causing the steering wheel to wobble.

Interesting note though, the top mounts which came off the car were a BMW part but were not the Z4M part no as specified by BMW - they were in fact the part no for an M5 / M6 2005 onward models. They looked original as well as the top nut still had the torque paint from the factory.

Bit of a strange one & possibly why they have failed!?
 
That's peculiar, good you found the problem though. I presume there's no evidence of crash damage elsewhere that might suggest they were replaced after a the originals were damaged?
 
Perhaps the previous owner had a strut brace fitted & removed it when he sold the car hence the different mount bolts ? :?
 
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