Brake Judder

[starmist]

I bought a second hand set of Wilwood 4 pots and 300mm disks which when braking from high speed (building up some heat) start to judder.

Anyone any ideas what might be causing this?

[stesrg]

starmist said:

I bought a second hand set of Wilwood 4 pots and 300mm disks which when braking from high speed (building up some heat) start to judder. Anyone any ideas what might be causing this?

And what pads are you useing ? hard / soft

[ferlin]

The secondhand brake discs could be warped.This would cause judder

[tvrgit]

you might have a piece of grit wedged between the hub and the disk flange, pushing the disk slightly to an angle. This is magnified at the disk edge and can cause "disk warp" sensation. I have known less skilled garages change perfectly good disks for this reason - ie they haven't fitted them carefully enough.

[GreenV8S]

Could be the discs are warped, or have surface contamination. This paper describes the problem:

www.stoptech.com/whitepapers/warped_rotors_myth.htm

[starmist]

Could be any of these things. I don't think the discs have been off the car since I first fitted them, but the symptoms only happen when the brakes get hot - i.e. if I brake hard, they are fine, only prolonged braking, when they get some heat into them causes them to judder.

The pads are standard Wilwoods, grade 3 of 5, I believe. (Too hard IMHO).