Greetings,
I've been reading Mud for a while and finally got my butt in gear and joined.
I've got an '83 PU that's truggy'd out. It's pseudo street legal, but rides on a trailer. I'm having a really strange brake issue and hoping that someone out there can help.
Description of brake system: Stock '83 booster behind 80-series (non-ABS) MC. I've got 2 line locks installed just past the MC, 1 on the FR circuit and 1 on the RR. From there the FR circuit goes through the factory hard lines to braided SS lines to IFS PU calipers. The RR circuit passes through the firewall right next to the MC and into a Willwood bias valve. From there the rest of the plumbing is SS all the way to the rear calipers which are factory '83 PU 4-piston units.
Here are the symptoms: Brakes feel great in the garage, very solid pedal feel, proper free play, etc. The brakes feel good initially on the trail, but after some length of time on the trail the pedal will go to the floor. If I pump the pedal a time or two the brakes will return and work normally. If I wait 2 or 3 minutes before applying the brakes again, same thing...pedal to floor, pump once or twice and things return the normal.
I've replaced the MC (properly bench bled) and it made no difference. None of the lines come anywhere near the exhaust and I'm not losing any fluid and can't see any leaks. It's not a fade issue in the traditional sense in that this condition will occur after a long steep hill climb at 2.5 MPH. It seems to be related to the under hood temp, no the temp of the friction surfaces, or that the brake fluid is boiling.
My current thought is that maybe the booster is bad. I'll replace that next.
THOUGHTS??? I'm stumped and frustrated, esp since I have to get the truck on the trail to get it to exhibit the symptoms. Even climbing the steepest/slowest hill (paved) around me won't cause the problem.
Thanks!
I've been reading Mud for a while and finally got my butt in gear and joined.
I've got an '83 PU that's truggy'd out. It's pseudo street legal, but rides on a trailer. I'm having a really strange brake issue and hoping that someone out there can help.
Description of brake system: Stock '83 booster behind 80-series (non-ABS) MC. I've got 2 line locks installed just past the MC, 1 on the FR circuit and 1 on the RR. From there the FR circuit goes through the factory hard lines to braided SS lines to IFS PU calipers. The RR circuit passes through the firewall right next to the MC and into a Willwood bias valve. From there the rest of the plumbing is SS all the way to the rear calipers which are factory '83 PU 4-piston units.
Here are the symptoms: Brakes feel great in the garage, very solid pedal feel, proper free play, etc. The brakes feel good initially on the trail, but after some length of time on the trail the pedal will go to the floor. If I pump the pedal a time or two the brakes will return and work normally. If I wait 2 or 3 minutes before applying the brakes again, same thing...pedal to floor, pump once or twice and things return the normal.
I've replaced the MC (properly bench bled) and it made no difference. None of the lines come anywhere near the exhaust and I'm not losing any fluid and can't see any leaks. It's not a fade issue in the traditional sense in that this condition will occur after a long steep hill climb at 2.5 MPH. It seems to be related to the under hood temp, no the temp of the friction surfaces, or that the brake fluid is boiling.
My current thought is that maybe the booster is bad. I'll replace that next.
THOUGHTS??? I'm stumped and frustrated, esp since I have to get the truck on the trail to get it to exhibit the symptoms. Even climbing the steepest/slowest hill (paved) around me won't cause the problem.
Thanks!
