What's next? I'll find this wobble if it kills me...

[Batesy9891]

I've got a JDM car for which parts aren't super easy to come by and have had a wheel wobble at motorway speeds since I got it not long ago. So when, after having the wheels balanced and finding the wheel wobble diminished but didn't go away, I had the brake discs skimmed.

Now I appear to have made the wheel wobble worse! I haven't replaced the pads because they were new only around 2000km ago.

What should I look at next? Current symptoms are a very light wheel wobble at motorway speeds when I'm cruising, which becomes more pronounced when I apply the brakes. At speeds <30mph it's not noticeable.

Is it naive to assume that the wheel balancers and/or disc skimmers couldn't have done an improper job?

TIA

[StuTheGrouch]

The wheels might be balanced, but are they free of any buckles?

Ball joints (track rod ends etc) might have some play in them too.

Instead of skimming the discs, I would just change the discs and pads. Then you can be confident it isn't the brakes. Could the caliper(s) be a bit sticky?

[Batesy9891]

I'd like to have replaced the discs but they're harder to come by as it's a JDM car with no equivalent over here. Skimming was the cheaper option but maybe I'll have to bite the bullet and buy some new discs.

Calipers are in great condition - no sticking or corrosion.

I've looked at ball joints and all of those are in good condition too - no noticeable play, and the boots are all looking clean and healthy too.

The engineering firm that skimmed them said they were out by 0.4mm originally but they said they corrected that.

Could the hub surface be out of true? It only has around 60,000kms and the underneath is pristine - no corrosion anywhere (as you might expect from an import).

[Batesy9891]

StuTheGrouch said:

The wheels might be balanced, but are they free of any buckles?

I hadn't actually considered that. How would I check for it? Would that not have been picked up at balancing? To my untrained eye they look great.

[StuTheGrouch]

Batesy9891 said:

StuTheGrouch said:

The wheels might be balanced, but are they free of any buckles?

I hadn't actually considered that. How would I check for it? Would that not have been picked up at balancing? To my untrained eye they look great.

I've had alloys with buckles in them, but not serious enough to prevent the wheels from being balanced. The wheels would need to be put on a balancing machine again, but this time ask the technician to check for any abnormalities. From my own experience the inner rims are where the damage is usually located, so I guess you could take the wheels off and have a close look.

Another option, but for after looking for damage on the rims, would be four wheel laser alignment. Unlikely to cause the wobble you describe though.

[itsnotarace]

Try and get it road force balanced. If its only noticeable at certain speeds its almost certainly due to balance as the frequency increases or decreases with speed

Also worth getting checked for roundness, might have been kerbed or potholed which is enough to throw it out of true

[GreenV8S]

Given that you made the problem worse by skimming the brakes, I suggest you check the hub is straight and true, and the brake and wheel are seating cleanly to it and each other. If you spin the wheel with a fixed reference close to the tread and sidewall if will be obvious if there is any distortion or runout.

[PositronicRay]

I purchased an old merc, always had a steering wheel shimmer.

I started with wheels, discs and tyres, progressed to suspension, shocks, top mounts, ball joints, control arms, rubbery bits, steering and alignment.

None of the changes were definitive, but each made a little difference, enough that it's no longer noticeable. Took time and money.

Good luck, mine was a frustrating experience.

[nsa]

Does it have aftermarket wheels or spacers? If so are they hubcentric?

https://www.superforma.co.uk/hubcentric-explained

[Batesy9891]

PositronicRay said:

I purchased an old merc, always had a steering wheel shimmer.

I started with wheels, discs and tyres, progressed to suspension, shocks, top mounts, ball joints, control arms, rubbery bits, steering and alignment.

None of the changes were definitive, but each made a little difference, enough that it's no longer noticeable. Took time and money.

Good luck, mine was a frustrating experience.

Thanks - I'm beginning to worry it might be the same as what you experienced!

GreenV8S said:

I suggest you check the hub is straight and true, and the brake and wheel are seating cleanly to it and each other. If you spin the wheel with a fixed reference close to the tread and sidewall if will be obvious if there is any distortion or runout.

Hub was what I was worried about too. Think I'll get myself a DTI gauge for the hub and will look at the wheel as you describe, thanks.

itsnotarace said:

Also worth getting checked for roundness, might have been kerbed or potholed which is enough to throw it out of true

Will try that too, thanks.

StuTheGrouch said:

Another option, but for after looking for damage on the rims, would be four wheel laser alignment. Unlikely to cause the wobble you describe though.

Alignment is a good call just to eliminate that, thanks. Will add that to the list!

nsa said:

Does it have aftermarket wheels or spacers? If so are they hubcentric?

https://www.superforma.co.uk/hubcentric-explained

It doesn't - no spacers and on factory alloys. Thanks though.

If I find out what it is, I'll post it back here for the sake of future wobble hunters...

[sunbeam alpine]

Have you tried swapping the wheels round? If the problem moves, it may help.

I had a wobble which was due to a tyre which had an internal fault.

[Batesy9891]

sunbeam alpine said:

Have you tried swapping the wheels round? If the problem moves, it may help.

I haven't as it happens, but that's a good idea. And cheap! Thanks.

[Batesy9891]

Just to close this thread, I bit the bullet to the tune of £150 and got new discs from Japan. I also stuck new pads on them.

Whilst everything was off I measured hub runout with a DTI gauge - admittedly not a super expensive one but good enough for this task - and got 0.02mm, which is close to the max permissible limit according to manufacturer's spec but still acceptable.

I gave the caliper and bracket a thorough clean - previous spanner of a mechanic had just put lithium grease everywhere, and I mean everywhere - and now I have zero wheel wobble under breaking. Smooth as the proverbial smooth thing. I still have a slight wobble at 120km/h+ but I'll put that down to the wheel balancing not being 100%. There's no trace of it at speeds lower than 120km/h so I'll leave it.

So the lesson for me is: don't bother with disc skimming. The only reason I tried this somewhat dated approach is to try to avoid the cost of the imported discs. In the end I just p**sed £50 up the wall when I should've just spent the £150...