I converted front drum to stock disk brakes on 68 Camaro RS. Put in power brake booster and changed master cylinder and put proportioning valve. But when I engage the brakes they lock up. Any suggestions on troubleshooting will be greatly appreciated. Thanks guys!

 

are the brakes you put in used? if so see about checking the piston out, make sure its not sticking. also, make sure all the vacuum lines are secure on the brake booster.

 

Does it lock up and stay locked? Or are you just not used to good braking in that car???
Is the rod inside the booster adjusted proper?