Mirage brake option of the 'vette guys

Because there is no "brake" section on this forum, I'm posting this here.

Some of us have utilized the C4 brakes on our cars, which is what I have done as well. One caveat to this option was my use of aftermarket 4-piston (Outlaw 4000 series) calipers with these C4 rotors (rather than the OEM factory calipers). Recently I tried to find a higher performance aftermarket rotor set-up for the C4 configuration from Wilwood, but unfortunately, they only offer it for the 13" rotors (the Heavy Duty option) and larger. Mine are 12" rotors for two reasons. 1) the McLarens used 12" rotors, and 2) these were the largest ones that would absolutely fit inside a 16" wheel (and a 15" wheel given the perfectly designed wheel). So recently I called Wilwood, but the sales person was not helpful in wanting to find a hat/rotor combination that would replace the C4 12" rotors. So I took pen to paper, and noted all dimensions of their parts, and came up with a very close assembly that may need only a .040" shim between my calipers and the mounting boss in order to use Wilwood 12.19" racing rotors and hats in place of the OEM C4 12.00" rotors. I've inserted photos of the rotors (OEM and Wilwood as a comparison) showing how they compare to each other in offset. The hat I'm using is their "drag" hat that has a 1.16" offset. Because the hat mounting flange is about .043" thinner than the OEM rotors, this will require the previously noted shim to make up for the difference. Other than that, the OEM rotor was .790" thick, whereas the Wilwood is .810" thick, so they are very similar in size.

Another reason for experimenting with the Wilwood parts is that they are lighter in weight, better metallurgy than the OEM, plus they are more flexible in rotor dimensions. With this said, I could simply increase the thickness of the shim, and then use a 1.25" rotor instead of this .810" rotor for only an additional pound of weight. For those that simply want to jazz up their street set-up, Wilwood has some very inexpensive, super-lightweight straight vain, medium temperature rotors that would work very well for street use.

http://www.fototime.com/30F4BAE86EC1B75/standard.jpg

http://www.fototime.com/AE4A45012829025/standard.jpg

http://www.fototime.com/7B60D09512174CB/standard.jpg

Those look very close. Let us know if you need to shim.

I am certain I will (math doesn't lie). The main reason is the Wilwood's thinner hat material (.25" aluminum) as compared with the OEM hat material thickness of .293". This is about .040" that gets at least the outboard face in the same plane as the OEM rotor. The reason why this is so critical is because my calipers are very close to the three-piece wheel assembly bolts, so the caliper cannot be allowed to move any further outboard. Being the calipers are mounded inboard of the brake mounting boss on the upright, this allows me to shift the caliper inboard by any amount I want to, so this will end up being pretty flexible, and allow me to burn up some cheap OEM rotors with extremely aggressive pads on track day, and then run the super-light rotors with street pads in between track days.