E39 M5

[andy3781]

Hi all,

Just putting the feelers out before i stick an ad up to see if anyone here is interested in a used pair of E39 M5 front discs for trackdays or whatever? I removed them from my 1999 car as i thought they were warped, turned out after dismantling everything and having already bought new discs and pads that the osf piston in the caliper was the offending item and so the discs were fine. With having shiny new discs infront of me, i decided to change them anyway. So these are now surplus to requirements. Anybody interested then please message me with an offer, will be fairly cheap because they are taking up space now and i'm getting grief from "her in doors". Think they've got around 20-25k miles and thats all motorway mileage. Also, i've not tryed to clean them in anyway so they are as they came off the car so are sporting surface rust.

Cheers Andy

[CarbonBlackM5]

Andy, don't want the discs but was interested to know how you identified a knackered calliper. Mine goes in again today with shudder after the discs were replaced under warranty in Oct. I have checked that the wheels don't get hot but they are fine.

[plenty]

This article gives a point of view on the "myth" of warped discs.

Carbon, have you tried re-bedding your pads and checking your upper control arm bushes?

[andy3781]

Basically once the disc were off and the calipers were exposed, the mechanic put the piston retractor into the caliper and one of the pistons wouldn't budge or push back so we could get to put the new pads in, hence when driving it gives a warped disc effect like a small shudder. It wasn't a violent shudder but got very annoying. Since i've had this done, apparently BMW do a rebuild kit for the pistons. Also found out that the caliper is basically the same as a 540 without the ///M stamped carrier.

[CarbonBlackM5]

Well, the dealer has confirmed the discs are fine so I am a little stumped because all the other components are fine. I did try the mentioned bedding in process on the last discs so I will probably give it a try on this set because Im not sure what else it could be otherwise.

[plenty]

A tyre or wheel perhaps? Could you obtain a different set of front wheels to try?

[CarbonBlackM5]

I know one of the wheels is slightly buckled because I went down this route before. However, the tracking and balancing seem fine and there is no indication of any problems when driving at speed until I use the brakes.

Im going to find a quiet road tomorrow and try the bedding in process and see what that does. I also found out that I need a new Oxygen Sensor and thermostat .

[DVandrews]

A few years ago I had a similar problem with an E39 540i, turns out that the material on the pad had a hairlie crack across the centre and this had destabilised the pads, as they heated up the pad backplate would distort causing the vibration and shaking, a new set of pads and careful running in fixed the problem permanently (they were OE pads both times).

Dave

[CarbonBlackM5]

Last night I carried out the bedding in procedure and this morning they do feel a whole lot better.

Im going to replace the reaction bushes with Powerflex ones too so hopefully that will help.

I think I will get them to check the pads too.