Brake Disk Float Tolerance

Brake assembly          Section view

In order for the brakes to function with the most efficiency and least wear, it is imperative that the calipers and brake disks should line up exactly. If they are off by even a few mm, it will force the brake disk to be bent at an angle by the calipers. To prevent this from happening, it is a good idea to allow the brake disks to float on the bobbins so that when the calipers press the break pads onto the brake disks, the break disk can move over the distance necessary to be aligned. 

To calculate the float distance necessary, the variance of all the parts that will effect the alignment must either be calculated or estimated. 

The variance

-on the upright: 0.05mm

-on the spindle: 0.1mm

-on the hub face: 0.05mm

-on the calipers: 0.15mm (obtained from Wilwood phone call)

-on the brake pads: 0.17mm (on Wilwoods website it says the pads are 7.6mm thick, after taking an average of a sample of pads 7.59mm was found. The lowest thickness was 7.48mm and the largest thickness was 7.77mm so the variance was taken.)

TOTAL VARIANCE: 0.52mm

The brake disk/rotor can be between 0.15"-0.20" thick. Ours is currently a little bit too thin. 

http://www.wilwood.com/Calipers/CaliperList.aspx?subname=PS1