640 GC shudder under heavy braking

[CSK423]

Car has nearly ticked 20k miles and has over 10k left on the front brakes (bit more on the back).

3 Tyres have around 3-4mm all round aswell, one only has 5k miles on it.

Under light braking from 70mph there is no shudder but as soon as you apply a bit more pressure the car shudders slightly almost as if you're going over a bumpy surface. The steering wheel ever ever so slightly shakes, again feels as if the road surface is bumpy. No shaking through the brake pedal.

I didn't notice it and must have gradually grown a custom to it, it was the wife as a passenger that commented and drew my attention to it. Now I feel it all the time !....to the point I'm starting to think it's getting worse.

I bent a wheel around 5k miles ago, now repaired and new tyre but felt not shaking during or after that and it's been into BMW for a service where I specifically asked them to check the suspension.

All tyres are wearing correctly so no misalignment issues.

Anyone came across this before ? I'm starting to think a sticky caliper ?

[CSK423]

REALIST123 said:

My 5 series does it. Brake from 70+ it's OK and at low speeds it's OK. You feel it between about 60 and 40.

It's apparently very common and often down to the discs having some pad pick up or localised corrosion that causes the vibration. I plan to have the front discs skimmed unless someone on here knows better, which may well be the case.

My car was fine until it was left standing outside for a month back in February, it's normally garaged. I don't know if that's connected but I'm positive that's when it started.

Interesting as the car sat for nearly 3 weeks on my driveway last month.

[CSK423]

Turns out it’s a warped disc off side front only and the reason it’s warp is due to the heat not being dissipated properly...and why hasn’t it been dissipated ? because the alloy has been refurbed and in doing so the hub of the alloy was painted which meant the heat transfer from the disc to the alloy hub is unable to happen and in turn warps the disc with excessive heat build up.

Google confirms this theory with many BMW owners experiencing the same thing.

The dealer removed the hub paint on the alloy to stop it getting any worse (won’t get better) they wouldn’t skim the disc but suggested new front discs and pads at £700.

I’m going to get the disc skimmed at £95 as front brakes are reading11k miles left, if it was 4/5k I would change them.

[CSK423]

ashway said:

Ive had loads of alloys referred over the years but never had this problem, which part of the wheel has been painted that shouldn't have. Is it the surface of the wheel that mates to the wheel hub. The hub itself is not part of the wheel so not sure why that would have been painted?

Yes the surface of the wheel that mates with the hub.

[CSK423]

REALIST123 said:

Whilst perhaps not being good practice to paint that surface, for mounting accuracy reasons, I struggle to accept that that could cause a disc to warp. Warped discs are very rare, in fact, they more normally suffer from surface issues that cause vibration.

A painted surface might theoretically slow the rate at which the heat passed through to the wheel but why would that cause a disc to warp?

Sounds like a convenient peg to hang it on to me.

I've still got the issue, original wheels still fitted. Just trying to decide whether to risk the dealer's fairy tales or just have the discs skimmed......

I checked both fronts and the OSF (refurbed wheel) drags on the pad when spun, the NSF (original finish) does not. It's not able to dissipate enough heat which results in the disc warping, this has been after circa 5k miles and generally braking from motorway speeds, it's taken a while and high speed braking to warp it. I have no doubt someone tootling around town probably won't see this level of heat build up and will never suffer the same consequences or it'll take a lot more mileage.

I would challenge your dealer and see what response you get, you don't ask you don't get.

[CSK423]

REALIST123 said:

Dino D said:

CSK423 said:

I checked both fronts and the OSF (refurbed wheel) drags on the pad when spun, the NSF (original finish) does not. It's not able to dissipate enough heat which results in the disc warping, this has been after circa 5k miles and generally braking from motorway speeds, it's taken a while and high speed braking to warp it. I have no doubt someone tootling around town probably won't see this level of heat build up and will never suffer the same consequences or it'll take a lot more mileage.

I would challenge your dealer and see what response you get, you don't ask you don't get.

I'm trying to work out how the wheel/paint can cause the pad to drag on the disc?
Or have I missed something?
It's the dragging that causes the heat regardless of what wheel is on that side if have thought?

I think the theory is that the paint caused the warping and the warps disc now rubs on the pads at some point in its rotation, which is understandable.

Thing is,this is a very common problem with the F10, I doubt there are that many refurbished wheels involved.

Dino - it's as REALIST has said.

[CSK423]

DinoD - If this had been a set of discs I would agree and contest further but as it's only one and is mounted to the refurb wheel I don't have anywhere to go with it but to accept this is the cause. If it was a pair I would be having a different conversation with the dealer.

I had both the front dics skimmed (only the OSF was warped) at a cost of £99. No more shudder and it's only after this has been done I can tell how bad the shudder was previously, I must have been growing use to it as it gradually got worse.

I know the disc will always have a slight imperfection from where it previously warped but hopefully it won't heat up the way had previously for the warp to return. Time will tell.