Warped disc - Oooops!
Discussion
Just been given the bad news that the slight vibration under braking is a warped disc. It's off for skimming... 300mm monster brake upgrade and I still managed to warp the discs 
Also my rear pads are 85% worn in 12000 miles
I know I drive 'enthusiastically', but this is ridiculous! I can't blame my recent rev-limited laps at Castle Combe as I never even smelt the brakes.
Also my rear pads are 85% worn in 12000 miles
I know I drive 'enthusiastically', but this is ridiculous! I can't blame my recent rev-limited laps at Castle Combe as I never even smelt the brakes.
Green stuff all round.
I do get quite a lot of brake dust on the front alloys after as little as a blast around the block (8 miles).
Unlikely to be brakes stuck on as this set of pads were fitted to freshly refurbished brake calipers. I haven't asked whether the wear is even both sides but I'm assuming it is as Peninsula haven't mentioned that either of the calipers needs attention.
I do drive quite enthsiastically and it's quite normal for me to be able to smell the brakes as they warm up in a good stretch of twisties. The stretches I use are kind of 25->50->35->70->30->65 etc, etc. I.E. max acceleration, max brakes for four miles plus...
Putting this in perspective, I didn't smell the brakes while going around Castle Combe recently; probably greater cooling effect due to the higher speeds and greater time between periods of hard braking.
I could certainly smell the brakes at the end of the Duxford runway last year
I do get quite a lot of brake dust on the front alloys after as little as a blast around the block (8 miles).
Unlikely to be brakes stuck on as this set of pads were fitted to freshly refurbished brake calipers. I haven't asked whether the wear is even both sides but I'm assuming it is as Peninsula haven't mentioned that either of the calipers needs attention.
I do drive quite enthsiastically and it's quite normal for me to be able to smell the brakes as they warm up in a good stretch of twisties. The stretches I use are kind of 25->50->35->70->30->65 etc, etc. I.E. max acceleration, max brakes for four miles plus...
Putting this in perspective, I didn't smell the brakes while going around Castle Combe recently; probably greater cooling effect due to the higher speeds and greater time between periods of hard braking.
I could certainly smell the brakes at the end of the Duxford runway last year
Hmm , warped two sets of discs on the Chimaera , less than 5k each set . Brand new EBC discs and green stuff . Green stuff on both the 400 and the SEAC , but those discs are fine , and to be honest I am lighter on those brakes ( Lack of confidence in them )
This isn't a case of hot brakes and holding the car on the pedal rather than the handbrake ?
This isn't a case of hot brakes and holding the car on the pedal rather than the handbrake ?
I'll try to dig out the article tomorrow. It was written by an engineer who helped to develop the brakes for the original GT40 amongst other things. In 40 years in the motor industry and motorsport he'd never seen a warped disc. Many people had come to him supposedly with warped discs but that was found never to be the problem. Warped discs do seem to be another urban myth.
19560 this is a link to the article you were thinking of.
Duncan, don't rush out and get the discs skimmed until you have read this.
www.stoptech.com/whitepapers/warped_rotors_myth.htm
Duncan, don't rush out and get the discs skimmed until you have read this.
www.stoptech.com/whitepapers/warped_rotors_myth.htm
I've got to admit, that explanation feels right!
When I'm at really low speeds, there is a pronounced grab in every wheel revolution that I've never felt entirely comfortable that a bent disc could cause that much grab. A sticky disc on the other hand fits the symptoms very nicely.
With the monster brakes I probably never get anywhere close to the use/abuse needed to prevent deposits forming on the disc. This also makes complete sense.
The article does mention that in bad cases the discs sould be skimmed as a start point for their reccommended procedure. It notes that this is not a cure as the problem will quickly reoccur.
So I plan to let Penninsula finish the skimming and then go and practice what that article preaches.
Top stuff - thanks all
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