On-going M5 brake issue...
Discussion
What the hell is wrong with my car? 
New discs, new pads, all checked with whatever that cunning thing is that detects warps and other imperfections, all seems ok. Everything clean too.
But still, horrendous vibration via moderate-heavy braking, now confirmed by two colleagues and two mechanics.
Not keen on the local dealer because they employ escapees from a nearby kindergarten.
(Just had all the wheels balanced on and off the car and it drives more sublimely at any speed than I can recall - it's just these infernal brakes!!!)
Help, somebody, please!
New discs, new pads, all checked with whatever that cunning thing is that detects warps and other imperfections, all seems ok. Everything clean too.
But still, horrendous vibration via moderate-heavy braking, now confirmed by two colleagues and two mechanics.
Not keen on the local dealer because they employ escapees from a nearby kindergarten.
(Just had all the wheels balanced on and off the car and it drives more sublimely at any speed than I can recall - it's just these infernal brakes!!!)
Help, somebody, please!
derestrictor said:
What the hell is wrong with my car?
New discs, new pads, all checked with whatever that cunning thing is that detects warps and other imperfections, all seems ok. Everything clean too.
But still, horrendous vibration via moderate-heavy braking, now confirmed by two colleagues and two mechanics.
Not keen on the local dealer because they employ escapees from a nearby kindergarten.
(Just had all the wheels balanced on and off the car and it drives more sublimely at any speed than I can recall - it's just these infernal brakes!!!)
Help, somebody, please!
have the same thing at the moment, had the wheels balanced and the noticed the near side front wheel is slightly egg shaped, could be this although it only happens under braking so am not so sure, if I find out before the car is sold I'll let you know, not much help i know but at least your not alone
Nik
Your disks are either warped or more likely they have differing coefficients of friction on the surface due to the pads heat soak annealing the the steel after a they have got hot. Localised heating via the pad and caliper in one place that has been allowed to cool slowly has changed the crystalline structure near the surface and made the friction un-uniform as the rotor turns.
If the disk has this friction difference it is pain to cure as usual skimming is not effective. The easy remedy is change the disk or skim the surface by lathe when the disk is very hot (and this needs specialist kit)
My AP's suffered from new from this and I tried twice to skim them, eventually accepting defeat and buying new rotors. They are now perfect. I do not to this day know why they "warped" or similar, so early in their life, but running in high spec brakes is a black art and a bit hit or miss.
You should ask the dealer to rectify the issue under warranty if the parts are OEM and fitted by them.
If the disk has this friction difference it is pain to cure as usual skimming is not effective. The easy remedy is change the disk or skim the surface by lathe when the disk is very hot (and this needs specialist kit)
My AP's suffered from new from this and I tried twice to skim them, eventually accepting defeat and buying new rotors. They are now perfect. I do not to this day know why they "warped" or similar, so early in their life, but running in high spec brakes is a black art and a bit hit or miss.
You should ask the dealer to rectify the issue under warranty if the parts are OEM and fitted by them.
Brakes still juddering ? E39 M5'S have an additional suspension arm designed to absorb the force of baking, basicaly on a 5 series you have a lower wisbone, macpherson strut and an anti roll bar. On an M5 you get an extra arm on each side which prevents the lower wishbones flexing backwards under heavy braking (cannot for the life of me remember what its called!), the bushes on these can ware causing brake judder like affects.
derestrictor said:
What the hell is wrong with my car?
New discs, new pads, all checked with whatever that cunning thing is that detects warps and other imperfections, all seems ok. Everything clean too.
But still, horrendous vibration via moderate-heavy braking, now confirmed by two colleagues and two mechanics.
Not keen on the local dealer because they employ escapees from a nearby kindergarten.
(Just had all the wheels balanced on and off the car and it drives more sublimely at any speed than I can recall - it's just these infernal brakes!!!)
Help, somebody, please!
not the ABS cutting in when it shouldn't is it
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