I converted to Wilwood front disc from stock drums on my 70 GS a few years ago. The front brakes always felt tight and hard to turn the front tires with the car jacked up in the air. I figured the pads would wear in a bit and loosen up. After BG this year, I jacked the car up, and I could barely turn the front tires by hand. Maybe thats where my MPH is hidden all these years? Anyway, I pulled the brake pads and the rotors spin over nice and easy. Re-installed the pads and the rotors are tight again. The rotors dont appear to be warped, and the rotor/caliper alignment is perfect. My 4 piston calipers are Wilwood. Always stopped the car good, no problems there. I have the stock type non power master cylinder, bought at Autozone and supposedly for disc brakes. The pistons in the calipers are very hard to push back after pressing the brake pedal, infact you have to pry them back with a small prybar. I have not installed an aftermarket residual pressure valve, but dont know if there is one in the master cylinder. How can you tell? Does this make sence to anyone? Should I go with a light master cylinder from Strange and ditch the stock type? Or is the problem with my calipers? I know this is killing et and MPH, and probly always has. Thanks for any help or advice.
do you have a residual pressure valve in your master cylinder? Make sure you have the M/C for a disc brake car.
Some of them can be seen in the fluid bowl or in the hole where the brake line fitting is. I've never actually had to remove one, as I replaced my master cylinder when I did the swap. If you didn't replace the M/C or remove the valve when you swapped out the drums then I'd expect that is it. You can get a brand new M/C from autozone for about $35. Just order it for a disc brake car.
Pressure is being held up in the system somewhere. Adam is right. I would start with a different (disc brake) master cylinder. Make sure there is play at the top of the brake pedal. The proportioning valve can cause similar problems if the new master doesn't do it.
