[NathanJT]

I had my front disks and pads replaced by a local independent last August through no other reason than general wear. However after about 3 months of driving they'd built up to an intolerable squealing on braking and also a severe wobble when braking at motorway speeds. It wasn't as noticeable at slower speeds.

Anyway, the garage had the car back in just before Xmas and they replaced the disks under warranty claiming that they were warped. I'm happy with this, however it's now doing it again!

The car has been with the dealer today and they've come back stating that the local BMW dealer has had an issue with a certain batch of disks and that a new set will be coming direct from the factory, which they'll again be replacing under warranty.

My concern though is what might this have done to the rest of the car?

Should I expect that they'll be replacing the pads as well as surely they'll have worn irregularly?

How can I tell that they've used original BMW parts?

Is an OEM part more likely to suffer this issue?

And also looking on the "oh sh!t ££££" side of things; if it's NOT a bad batch as BMW state, what could be the potential root cause?

Thanks in advance.

[Dr Dave]

I bet they didn't use OEM discs.

And they've used copperslip or similar between the disc and hub.

Warped discs and excessive DTV is usually attributable to poor fitment practice.

I have a specialist on-car lathe to correct out-of-true brake discs :-/

[Em135eye]

My OE disks warped at 31k miles. Replaced and all fine - used Bosch disks and pads.

[F31-340i]

Originally Posted by NathanJT

I had my front disks and pads replaced by a local independent last August through no other reason than general wear. However after about 3 months of driving they'd built up to an intolerable squealing on braking and also a severe wobble when braking at motorway speeds. It wasn't as noticeable at slower speeds.

Anyway, the garage had the car back in just before Xmas and they replaced the disks under warranty claiming that they were warped. I'm happy with this, however it's now doing it again!

The car has been with the dealer today and they've come back stating that the local BMW dealer has had an issue with a certain batch of disks and that a new set will be coming direct from the factory, which they'll again be replacing under warranty.

My concern though is what might this have done to the rest of the car?

Should I expect that they'll be replacing the pads as well as surely they'll have worn irregularly?

How can I tell that they've used original BMW parts?

Is an OEM part more likely to suffer this issue?

And also looking on the "oh sh!t ££££" side of things; if it's NOT a bad batch as BMW state, what could be the potential root cause?

Thanks in advance.

Sounds like it might be non-genuine iffy parts to me - but could be anything.

You can't normally replace discs without replacing pads at the same time - they tend to bed into a given disc. In others words, new discs always need new pads.

Did they just refit the old pads??!?

[toxicnerve]

Are you sure it's not just uneven transfer of friction material from pad to disc?

Warped discs are much rarer that some might have you believe and more often than not when you experience wobble/rumble under braking it's because there are deposits of friction material on the disc in patches etc.

Try doing the usual "bed-in" procedure and see if that cures it...

[m1bjr]

Dave is right on the money.

I guarantee they never did a run out check with a DTI.

The disc is esentailly fitted a bit 'cock-eyed' but that alone isnt really noticable when new.
But because of this when braking hard and over a few thousand miles, the high spots wear faster and can also overheat.
Localised wear means the disc is thinner in some places and also the localised heating hardens the cast iron into cementite.
That's why the judder takes months to appear, genrally at speed and therefor high temperatures (long braking from 100+) at first.
Your pads are squeezing a rotating disc that is thicker in one place than another as well as being harder in places where its being cooked.

Cast iron wont warp. I have cracked a couple but not for many years and both were drilled.

Dr Dave, I have a little excess runout in a hubs, do you own the facility to grind new discs on the car as I wouldn't mind getting some mileage out of these new EBCs.
(ICBA to start fitting new hubs as I dont get through a lot of metal normally)

Ref. the runout on the new EBCs- was impossible to get all of them down to their 0.05mm or less.
Oddly BMW normally quote 0.2mm maximum for oem, which I could get easily on each corner.
The trouble with a BMW disc is the drilled locating bolt and no studs - makes it hard to just rotate the new disc one hole at a time to get the runout as best as you can, its a PITA

Steve

[Em135eye]

Mine were scanned with some laser thingy - they were warped.

New disks and pads completely sorted it.