BMW 5 series (E60), new discs and pads on the front (at the same time), but getting a noticeable judder through the steering wheel under braking around the 50mph mark.

My summer wheels have recently gone back on, and am fairly certain they’ve gone back on how they were before I took them off. All bolts are torqued correctly (new bolts at BMW recently due to the b’stard locking wheel nut breaking), copper slip on contact points as well. Nothing seems untoward underneath.. any ideas?

ta

Warped discs or a build up on the surface. Also check behind the disc to make sure the mating surface between hub and disc is clean.

If the discs have really only just been fitted then the most likely thing is that the mating surface on the hub that the disc bolts to wasn’t cleaned up properly and the disc is running out a bit. If they were fitted by a garage, go back and have them sort it.

New discs are easy to warp if you brake hard before the pads have bedded in…..

How can they warp? Seen how think brake discs are? You need to re-bed the pads as there will be glazing/surface stuff that needs to come off. Online are some guides.

Same with if you sit on the brakes at lights after a spirited drive/braking. You’ll leave an imprint on the discs.

If it was warping why does it happen mainly at new pad/disc time? Its bedding in. Garages will tell you new pads/disc time though.

How can they warp?

Quite easily – warped loads of Brembo GT discs – expensive hobby at £600 a set…..

If the pads aren’t bedded in you get uneven friction which causes hot spots which causes them to warp (uneven expansion). They also soften in the hot spots, so even if you have them smoothed over in a disc lathe, they just warp again…..

You can also have problems on new discs when the bolts aren’t torqued evenly/correctly apparently- i.e incorrectly fitted discs by the garage.

I’m happy discs have been fitted well, I was there in the garage at the time at a friendly specialist, lots of rubbing down with wire brush and copper slip applied. Just like the !at speed” thread earlier, can wheel balancing do this, and/or alignment/tracking?

edit: also bed them in gently as well.

Warped discs most likely, you can get them skimmed

You can also have problems on new discs when the bolts aren’t torqued evenly/correctly apparently- i.e incorrectly fitted discs by the garage.

You ever fitted disks hora ?

All my bland mobiles have had little more than 2 m5 location bolts…..they were held on by the wheel nuts.

Disks are very easy to warp in the alps how ever doing it very quickly after changing inq the uk …. Id be pulling the wheels and making sure all the caliper bolts were done up right and all the moving bits were free to move.

Unless you have been track daying or alpine driving id be surprised if you warped the disks unless you fitted really crappy ones or there was. Material defect.

edit: also bed them in gently as well.

Try this- find a industrial park, accelerate to 60- brake hard down to say 10mph and repeat. Don’t sit on your brakes at any point or if you need to stop at lights during this.

Give this a whirl a few times. See if it helps.