Contour Enthusiasts Group Archives Forums Modifications Brakes First(I think) 13" Wilwood kit..INSTALLED!

damn it!...I'm not done with all my brake stuff and now I'll have no one to show it off to!

A kit the cover the whole area of a 13" rotor is going to start at 2,000-2,500. Mine was much less than that.

Learn how brakes work. Good reading out there if you want to find it.

You don't need to cover the entire rotor for the brakes to 'work' properly. In fact they'd likely work less if the pad were to be placed the other way. To cover the entire rotor would take about 12 pistons in my mind and one helluva big caliper. That's not how it's done.

How about giving us a quick overview, on how it is done, if it not too much to ask. You are the expert, but here is what I believe. (Any corrections(no flames) would be appreciated)

Braking torque is determined by a few things rotor size, pad pressure on the disc, pad center, and the co-eff of friction between the rotor and the pad(These are inhereint in the pad and the rotor)

Pad Pressure is determined by two things , caliper piston surface area and brake line pressure.

Brake performace (High speed, etc) is determined by rotor+pad heat capacity (this depends quite a bit on rotor mass), and the rotors ability to disappate heat.

So back to larger pads(same calipers).
Larger pads increase surface area on the rotor, but this has no effect on braking performance (only pad and rotor life). So where is the loss? it is that the center point of the pad is further in on the disc (also there is the added warmup time), thereby reducing brake torque.

Larger pad (larger calipers SA)
By increasing the size of the calipers, and accordingly pads, you now have more pad pressure on the disc, and this will (more than) compensate for the inward location of the pad.

So basicly large pad size has very little to do with performance (unless you are running endurance races, which none of us are)

Optimally we would all be running 15+" rotors with 12piston calipers, and also 19" wheels with 8.25" wide tires, and ... but none of us are actually competing in the supertourings races. Even there, the 12 piston calipers are still fairly close to the edge. The only question I have is why they don't turn the un-used rotor area into the best heatsink you can imagine.

Thanks

Pretty well. It's running Bilstein's PSS9 coilovers with adjustable damping. Upgraded sway bars all around. Upper and lower stress bars in front. Every single bushing is now polyurethane.

Brakes are half decent too, it's a 12.5" Audi TT conversion.. No Wilwood kit, but with a set of Hawke pads they have a lot more bite than I expected!

The suspension was setup on corner weight scales. It's the most neutral car I've ever driven, bar none. Lots of fun.

Geoff has it covered pretty well as I know it. And I have to state that I don't feel I'm an expert, only one with 8 years of hands on experience in manufacturing the kits you see here. It came about not as a result of being a brake engineeer, but rather my time at Bondurant, as well as later working on the SHO kits which statred it all.

For those who prefer to crunch numbers, start with The Brake Handbood by Puhn.

In short, a slightly larger rotor with perhaps 1200 psi line pressure, put through a high Cf pad will provide much improvement.

The only comment I can add is that 'bigger is better' is not always true. With the proper pad and a reasonable size rotor (12.2) using only the smaller NDL caliper will net results that are well within the needs of most drivers. We can of course build bigger, badder kits, but the cost certainly goes up rapidly and the results are not going to keep up with it except at the most extreme levels.