Archived brake combination valve or rubber lines

[RCapehart]

I have just put the 2nd master cylinder on my 96. I still have brake fade. I made some plugs out of old brake line to plug the MC. When I plug the rear and have the front hooked up I get the fade. I have no leaks. My only choice is the combination valve or the rubber lines. I can not detect any swelling with the lines. Could they be breaking down inside? Any ideas?



Ron

 

[SDrake]

What are you referring to as brake fade? Are you talking about a spongy pedal which can be felt while sitting still or you describing something that happens in a road braking situation. I don't get the connection between fade and the master cylinder (MC ?) malfunctioning.

 

[RCapehart]

What are you referring to as brake fade? Are you talking about a spongy pedal which can be felt while sitting still or you describing something that happens in a road braking situation. I don't get the connection between fade and the master cylinder (MC ?) malfunctioning.

I guess brake fade is not the right term. Sitting still the pedal falls away when I hold steady foot pressure on it. I have no leaks so we thought that it was a MC leaking internally. I first put a rebuilt on it. Still had the problem. I took it to the dealer and they checked it for codes because of the anti-lock and brake lights being on. No codes. They thought I had a bad rebuilt MC. So I put a new one on it and still have the problem. I made some plugs out of old brake line and plugged the MC off. With the rear plugged off and the front hooked up the pedal falls away under foot pressure. Again I have no leaks. So I am looking at the rubber lines or the combination valve.



Ron

 

[tp0d]

I recently redid my calipers, rotors, and brake lines. The crossover line from drivers front to passenger was in pretty bad shape, had to put a custom bender on there... I had a lot of fade before the work, but with the new setup, same booster and MC, I have none now. I rebuilt my rears about 4mo's before that. The front hoses I took off were wayyy more flexible than the new ones I put on. I`ve heard about fade because of this, but what you're describing sounds like air in the system. The pedal should stop at some point, not just bottom out.



good luck



-jerry

 

[LandShark]

I'm with tp0d. Sounds like air in the lines. Get yourself a couple of quarts of brake fluid and some help and bleed the lines until the fluid is clear and without bubbles. As I recall there are also bleed ports in the master cylinder/anti-lock controller area that also need to purged. This is all described in the factory service manual.

 

[Bschneider]

The hoses can collapse inside with no visible scars on the outside - you may not be able to tell anything is wrong simply by looking at the lines. If they look dry/cracked/time-worn, you may want to change them out anyway - they're not that expensive.