Problem with Wilwood Manual Brakes

[theastronaut]

Originally Posted by Keith Seymore

I ended up replacing the stock GM front calipers with some bolt on Wilwood dual piston calipers. That put me over the top. I'm now satisfied enough to drive it some and try it at the track. If I need more yet I can probably go to a more aggressive pad.

I still never got a firm pedal with 6:1 pedal ratio, which I can't really explain. I had the ability to drop to 4.5:1, which I preferred for the slightly less pedal travel and a little firmer feel (I don't mind pushing hard).

I also blew the pistons out of the original GM calipers and I'm thinking somewhere along the last 30 years I got some "quick take up" calipers on there accidentally. I believe the additional fluid requirements for those was not favorable. Probably time for some new front calipers anyway (they were the only remaining parts not new).

Sounds like quick take up calipers were the issue, they have to travel farther before the pads contact the rotor to actually start building pressure, by then you're out of pedal travel to build enough pressure. The Wilwood dual piston calipers that go in place of a D52 actually have less piston area than a D52 so they're making less clamping force than D52s, but since they're acting sooner (less piston retraction) you're starting to build pressure sooner in the pedal travel. If you swap back to regular early/non-QTU D52s you'd have even more clamping force.