[andyz0]

I had pads and discs fitted by my local (non specialist) garage a few months ago as my previous ones were knackered. However they have already warped and they are having a look tomorrow. My indi specialist said it was due to cheap discs and pads which don't cut the mustard. The local garage said they were decent discs. Should cheap discs warp so quick? What are a good brand to get? Is it reasonable to request they replace free of charge but then I pay the difference to upgrade to a good brand/oem discs and pads?
I do mostly motorway miles so not much braking required, so seems really premature.

Cheers!

[Digitalize]

Cheap discs, locking of brakes when hot, pads not being greased correctly, quick temperature changes. But I'd be saying cheap discs/a bad batch.

[DTB]

I doubt it will be warped discs. Most likely cause is the new discs and pads were not bedded in properly. Warped brake disc is actually a bit of a misnomer - the juddering is caused by an uneven build up of material on the disc surface not warped metal.

Sometimes when garages fit new discs and pads they take the car out to check the brakes and inadvertently make an arse of bedding in the brakes. Their test run might involve hard braking to a stop a few times at junctions which is absolutely the wrong thing to do with new brakes.

This article will probably do a much better job of explaining it than me.

http://www.mossmotors.com/SiteGraphi...ake_discs.html

Or this one

http://www.stoptech.com/technical-su...nd-other-myths

[phil200tdi]

Sounds like pad transfer as stated above..

Give this a try:

http://www.skimmydiscs.co.uk/

[dj219957]

seazed caliper piston would do this also assuming they are 2 or 4 pot setup. not sure how many there are on the e90

[Subzero2003]

I had genuinely warped discs on mine.

First fitted Pagid discs and pads and got judder after a few hundred miles. Then tried Bosch discs and pads had the same. Then tried genuine BMW ones and nothing.

I don't know what the difference with genuine BMW discs and pads were but they were completely judder free compared with two other sets of "OE quality" brakes. And there was no abnormal pad transfer either, the discs were completely clean and were bedded in properly.

[Subzero2003]

Op is this on a 335 or 330 with large discs?

[xenon]

Originally Posted by dj219957

seazed caliper piston would do this also assuming they are 2 or 4 pot setup. not sure how many there are on the e90

Precisely none, except after-market BBK.

It's also often caused by rust / debris build up on the hub flange which isn't cleaned off so when the new disc is fitted it's on the piss right from the start.

[doughboy]

Cast iron does not warp! It can have thickness variations, or wear unevenly, or be machined off-true, but it cannot warp, it will crack before then.

What ever the wobbles, vibrations etc it is not warped discs!

If it wobbles from day 1 then the dics are most likely not flush on the hub due to dirt / rust etc not being cleaned off, this can seem most like warping and give the worst steering wheel wobbles as the road wheels will be off-true also.

Or you may have uneven thickness (DTV, disc thickness variation) or uneven expansion causing high spots which overheat.

If it comes on over time it is 99% due to uneven pad transfer or hot spot overheating. Go and brake hard till it judders then stop and have a look at your discs, I be they will have blue patches or streaks on them.

Often high spots will occur where the ventilation spines are cast and the metal is thickest. This causes the rumbling / wheel wobbles etc but is not warping, it is a thermal DTV as above.

More often this is due to the pads rather than the discs. As soon as I put EBC red stuff pads on my OE discs, they began rumbling and hotspotting. Put Cheap ECP pads ones back on and problem went away.

OE pads are the same cheap Jurid or Textar you get from ECP etc, so they will give the best "factory" i.e. foolproof feel.

They are organic pad material and are very good at bedding in quickly and bein able to fully recover from overheating. But they trade off performance and fade resistiance, this is fine for 99% of users.

Try some OE / Jurid / Textar pads and see if that helps.

[Alex.J]

In steps the materials engineer and after fighting this on the forum before !

They won't be warped!

I see cast steel at 560degree's and being thermally cycled and it's happy!

I doubt a few degrees from braking will both a disc!

The man above me( doughboy) speaks truth!

[qa15ar]

i used pagid pads.... but they werent very good....

had to change discs and pads due to poor pads, swapped for Apec discs and pads.

When i took the disc of you could see where the pad had marked the disc as it was discolored

[dj219957]

warped or not. check the piston can move, the sliders are working and the discs are seated true.

[tmarshall57]

I had the same problem - felt like warped disks when I replaced the original OEM disks/pads with Pagids. The cause was me not ensuring the hub flanges were absolutely free of contamination. A small rust flake trapped between the new disk and the hub flange, or rust on the surface of the flange can cause the judder. A quick rub down with wet and dry on the disk and hub flange surface cured the issue.

[andyz0]

Thanks for your comments guys. I had them replaced for free. Watched them do it this time and they wore brushed and cleaned flanges first, also cleaned up the calipers. Only time will tell if this fixed the problem but at least it didn't cost me anything!

[Kerr]

Originally Posted by phil200tdi

Sounds like pad transfer as stated above..

Give this a try:

http://www.skimmydiscs.co.uk/

Any idea what the cost of this is roughly?

[phil200tdi]

I was quoted £100 all round.

Much cheaper than new discs/pads.