Hello everyone,

I have a break issue. Not anything like I've dealt with before, go figure. The master cylinder was said to have went out prior to it being parked ~8 years ago. It now has a new MS, one new caliper (said to have locked when the MS failed) and new gaskets / rings on the 3 remaining calipers. Here's what is strange: the breaks are soft when cold, go clear to the floor, the stop the car - but not well. Once she gets warm it feels like one or more of the breaks engage and hang and the pedal is exceptionally firm. Both of the afore mentioned conditions are, however, not consistent. Occasionally the pedal is firm (appropriately) from start and everything seems correct. When it acts up I get some vibration in the front end and can feel the motor pulling against a more significant load. I believe it to be on the drivers side front and rear, these are the wheels that smell hot and the rear started smoking a bit. I tried the reverse and stop trick thinking they just needed adjusted and it worked great initially but it quickly seems to bind back up. Once this occurs it will hold the car at a stop while in gear. Everything was too hot tonight when I got home so I worked on another issue and thought I'd ask for some advice in here while she cools down.

I greatly appreciate any advice!

 

If you apply the brakes and they don't release properly then look at the rubber hoses, the inside hole is very small and as the hoses deteriorates the hole gets clogged and acts like a pug (or check valve), and prevents the fluid from returning to the M/C.

 

That makes absolute sense. I'll pull the lines and replace. Thanks!!

 

Yes, you should replace all 4 brake hoses if old. 4 wheel disc brakes. The rear drum parking brake springs can break.

 

Alright! Rubber lines are replaced and the entire system has been bled. I'm fairly certain at this point that the guy that worked on the brakes failed to properly bench bleed the master cylinder. The pedal finally feels right! Now just need an extra couple of hands to get the new fuel tank in and i'll know for sure. Thanks for the advice everyone.

 

Update:

The pedal only felt right until I got the car started up, it then went back to a very soft pedal. I took it for a short drive and it remained soft until about 15-20 minutes into the drive. After a short trip down the freeway I began to feel vibration in the front end and the brakes got exceptionally firm. I'm sure one or more of the front brakes are still hanging up. The car would sit in gear and not move without pressing on the gas, and even then I could feel the motor pulling very hard against the brakes. At this point I stopped at a gas station and let it set for about 15 minutes to cool off. The whole time the motor was off, the brake pedal remained rock solid. When I started it back up to try and get back home, the brakes went back to soft!?!?

Anyone have an idea as to what is going on?

 

I believe I may have found my answer.

http://forums.corvetteforum.com/c3-t...n-lock-up.html

Going to try putting some washers b/t the master cylinder and the booster... we'll see if that does the trick.

 

Sounds like the pushrod between the master and booster is too long causing the piston in the master to not return fully and holding pressure in hte brakes. The soft pedal is likely air in the system yet.

With the brakes locked and hard, try loosening the nuts holding the master to booster and see if the front wheels release.