XSeries-forum

Hopeful for some extra insight.

Continuing with the ongoing programme of improving/maintaining the car. Done quite a bit so far on the mechanicals, with the latest round being brake fluid, air con regals and an intermittent vibration from about 50mph upwards.

Wheels have been balanced a few times with the new tires on. I thought it might be wheel bearings and it was booked in as such, but my specialist ( Darren Wood BMW) has confirmed that they are still good. They did point out the lower control arm bushes were shot ( 86k so makes sense) so we agreed to swap them out whilst it was there.. The car drives miles better, the steering is a lot tighter,so its another job off the list but alas, the wobble is still happening.

I've spoken to them, top blokes and they confirmed they checked all shafts at my request also checking the brakes for binding, all the usual/unusual stuff and they are stumped.

What are we missing?

Discs or sticky calliper maybe? Quick check is to go for a reasonable drive and if the issue occurs just gently touch the wheel hub (not whilst driving of course ) and if one of them is warmer than another it will be a sticky calliper. It’s quite common, as are warped discs. Sometimes the disc issue is caused if corrosion has got between the mating surface between hub and disc so slightly knocking a disc out of true and at other times a bit of demon braking will do it.

Other than that all that I can think of immediately is checking for a bent wheel (rim running very slightly out of true) or possibly an issue with a tyre. Neither will show up on a balancing machine.

its an odd one. And it looks like it might be a process of elimination that could prove costly until we find out what it is...

Wheels have been checked and balanced. I take your point about them being out of shape but they were refurbed recently and supposed to be ok. Darren Woods had them rebalanced as well and again, just to rule it out. Again, meant to be good ( few grammes out but not massive)

Also brakes. I suggested it could be brakes binding, they said checked and definitely not.

Could alignment potentially cause the issue? i haven't done it for a bit, but the last time it got looked at the tyre place said it was ok.

little things like this that piss me right off...

What about an on car balance? Just a thought.

Wheel runout will need a Dial Test Indicator against the rim to see if it moves.

I had an odd ‘wobble on the X6 and the alignment was fine when checked. The problem only occurred at random intervals and speeds and in the end was a stick calliper but it wasn’t constantly sticking so the warm hub test was the only clue. It would come and go so took a little while to find - mainly down the ideas from the assembled brain trust on this forum.

Any sign of a deformity anywhere on a tyre? Beyond that it’s blue sky thinking time and as you say a process of elimination!

Hi,

I've had some strange wobbles in the past!

Things that happened to my E70, and made things better; of course try the cheapest first:

Tracking - rear tracking (I think was toe) was out - was causing inner tyre wear so much that I didn't beleive the MOT man when he said my tyres had worn down to the cords. Vibration was there at anything above 50 MPH ish. It may have been the cords rubbing on the road, or just that the alignment was so much out that the lateral rubbing of tyres was causing the vibration. Had the lower control arms on the front of the car changed at the same time which made the steering tighter like yourself, but the vibration I think was down to the tyre alignment.

Rear Differential - Vibration (more like a rumble) again at moderate speeds. Couldn't fathom out what was causing this until the rear diff catastrophically failed. New/reconditioned diff fixed it on that occasion. Not sure how you'd detect it might be this without opening the casing. The oil that came out of mine was thick and black along with broken bits of gear. Maybe try an oil change and check the condition of oil if your car hasn't had one before. Mine went at about 80k.

Cheers.

Think the diffs are both ok, just had them serviced so lets hope so anyway.

The alignment is the next obvious thing so thats next on the list. I'm hoping that might make it better. Will report back.

Great cars, just getting on a bit!

Front calipers do tend to bind especially the twin pot ones, look for more brake dust on one side is a giveaway, it will be intermittent but will get worse as time goes on.

Well, doesn’t appear to have a binding calliper. Had a couple of drives in it and all hubs feel fine to touch afterwards. No extra warmth from any of the wheels so I think that rules that out.

4 wheel hunter alignment on Tuesday. Let’s see if that throws anything up.

okey dokey, so hunter alignment done.

toe and camber out at the back by quite a bit, and toe out quite a bit at the front.

They sorted the toe at the back, but camber bolts seized so thats still out. Toe at the front is worse as they could only do one side, so the adjustments they made have made it drive worse, with the steering wheel slightly off centre when going straight. Needs new track rod assembly...

So, new track rod arms and hopefully unseizing of camber bolts and another alignment required. Which might not solve the problem ( but its another thing off the might need doing at some point list)

Getting a bit frustrated with it now....Old shitters eh. Who'd have em.

From my experience of the E53 suspension (very similar) suspension bushes, ball joints etc are on their way out at around 80k causing odd tyre wear
Air suspension masks many worn components in particular the lower rose joints but my experience is if they are worn so is the rest. When I first got the 4.6 it had new tyres fitted (cheap ones I now believe fitted to mask the wear) inner tyre wear at the rear soon started to show as did front outer edge wear. After a bit of research and some reading here I decided to rebuild the suspension front and rear.
I brought front and rear kits from ebay plus Poly Bushes in the rear control arms, total cost was less than half that of a set of new tyres. I also replaced the eccentric bolts for toe and camber. Once full alignment was done the difference was a big surprise, the car drove well when I got it. After the rebuild it seemed quieter smoother and a bonus average MPG improved.