Edcase

Well, slightly more than a month after getting ProDrive Alcon 330mm brakes, the car has developed serious vibration under braking.

This only makes itself apparent when the discs are hot, but it is unbearable and makes the steering go light during braking.

Presumably this is a slight warp, that obviously gets exaggerated when the discs expand under heat???

Presumably they are covered by warranty? They are only just over one month old, and were bedded in religiously

johnfelstead

what pads are you using?

Edcase

What ever comes with the kit. I believe they are either 2000 or 2500's. Judging by the performance, I would guess 2000's.

johnfelstead

do you fancy getting your hands dirty?

Edcase

What did you have in mind?!

johnfelstead

quite often, what you think is warped disks, isnt.

You can get uneven pad deposits on the surface of the disk which when hot causes the same symptoms, quite often caused by running too hard a pad for the type of driving you do.

Take your disks off and go over them with some medium wet and dry using a flat block to wrap the wet and dry around until you have removed all the surface discolouration (usually a bit black, i dont mean rub the whole disk away just clean up the surface so you have clean metal). Then get the pads and laying the wet and dry on a flat surface like some plywood, rub the pad friction surface until it has a matt finish then wash it. Make sure you use plenty of water to stop the wet and dry paper from clogging.

Refit these and go try your brakes, do a few gentle stops first without putting too much heat into them or dragging them. If you are still getting a judder then you do have warped disks, if you now have good brakes you need to look into using diferent pad materials or change your driving style.

Edcase

Interesting John, thanks. I have to admit I was surprised, it just suddenly came on , during a not particularly spirited run. Previous to that they had been fine. Perhaps your theory is correct then!

Presumably also , the 2000 pad is harder than the 2500 pad?

Fat Boy

2000 is softer than the 2500 which is why you get pad deposition problems like the ones John is describing. A senior Alcon source has recently told me that ds2500 ( or as he said "the PF25 material, to be more correct"?) are the ones to go for, as long as you keep brake temps below 550C.DS3000 is fabulous in these brakes but it eats the disc and, as is usually the case with competition pad material, is also very noisy.

Having gone through a variety of pad materials and discs myself with the Alcon set up, I am now shifting my attention to cooling the brakes more effectively, so will be taking off the disc guard behind the disc on wednesday and then looking to sort out some sort of brake cooling pipe from behind the front splitter and aimed at the inside centre of each disc to see if I can stay below the magic 550C. Try to make this set last for a while as there may be a solution on it's way reasonably soon

Edcase

Okay thanks. I presumed this wouldn't be a problem , because that is what the grooves are for, but I guess when they get really hot and it expands it doesn't take much of an intolerance to make a difference.

Given how crap the standard fog lights are, I did seriously consider removing them altogether and ducting the air straight to the disks. Has anybody done this?

Presumably , the only use for the backing plates is to stop heatsoak?

Fat Boy

Not sure whether heat soak or not, but it's a good point, I'll have to be even more careful to cool them down after playing.

The orange or black triangle things would seem to be a good location for brake ducting as they don't do anything else. On the P1, which is what i've got, there are also a couple of vents in the splitter which i'm going to have a look at as well.