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View Full Version : Rear discs are locking up after a short drive



RBEAST
04-27-2013, 01:44 PM
I have a 68 CAMARO that I have installed corvette C-6 front and rear disc brakes on and it seems after a short drive the pedal comes up to top and gets harder until back brakes are locked up on car.

wilwood master cylinder, new 3/16 lines (hard) , new stainless flex lines, 13" front directional rotors, 12" directional rear rotors, calipers are in good working order, After installing new system and bleeding with a hand vacuum pump brakes worked excellent for about 15 mins of driving then i noticed the pedal was getting harder and was grabbing sooner than before and the back brakes were starting to grab and lock up without touching the pedal at all . glad i was close to home as i pulled into driveway they seemed to lock up completely so i let them cool down overnight and in morning they felt ok , i did some reading here to see what i could find on this issue and saw that i may have overfilled the master cylinder so i removed some of the fluid to where it was about half full and replaced cover and tried again to drive car , same thing happened again i checked brake temp after about 10 mins of driving and fronts were about 115 deg, rears were around 300 deg. that tells me same problem is still happening I have a wilwood prop valve that i didnt install as tobin from Kore3 said i wouldn't need it... also i am running lines directly from m/c to calipers (2 seperate lines for front and a single line to rear flex line with spliter block) i dont have any type of factory block or any thing else in my system (if that makes any sense)

help! any ideas why this is happening? i really had planned on making it to the so. cal challenge today but due to this it dosent look like im gonna make this event thanks in advance everyone

Hydratech®
04-27-2013, 02:29 PM
https://www.pro-touring.com/showthread.php?92619-Wilwood-Brake-Problems!&p=935412&highlight=#post935412

:6gears:

RBEAST
04-27-2013, 03:14 PM
I forgot to mention this is a manual set-up , I will try shims and report results.... THANKS PAUL FOR FAST RESPONSE!

Hydratech®
04-28-2013, 07:37 AM
A manual brake setup has an adjustable pushrod under the dash, and also a rubber pedal stop. Climb under the dash and back off the pedal rod adjustment (loosen the 9/16 jam nut and then thread the pushrod going into your horseshoe clevis further) instead of shimming the MC further out of the firewall. You should set it up for about a 1/4" of freeplay when the pedal is at rest. This will make sure that your MC pistons are being allowed to go into a full state of release when your foot is not on the brake, which should clear your problem up.

Apogee
04-28-2013, 11:59 AM
...I have a wilwood prop valve that i didnt install as tobin from Kore3 said i wouldn't need it...

While the proportioning valve being installed or not wouldn't create the issue you're experiencing, it looks like Paul has already addressed that, we generally recommend running an adjustable proportioning valve in a balanced system so that you can fine tune the lockup point of your rear brakes. I'm not sure where the misunderstanding came from, however I would never suggest that someone running performance aftermarket brakes front and rear not install an adjustable proportioning valve.

Tobin
KORE3