Here are the symptoms:
Went to raise the car to remove the left-front tire (used my 3-ton jack under the proper jacking point). Noticed that I hadn't broken the bolts free so I lowered it, I also checked the e-brake and noticed I forgot to pull that too (note to self: don't rush). I pulled the e-brake and it came up much easier than usual.

I then raised the car and did my maintenance and lowered it. When I backed out of the garage the brake pedal went to the floor! I pumped the brake several times and got out to look for the puddle, but there was none and the resorvoir was full, so I got back in and tried the pedal several more times and it felt ok.

So I went for a test drive. The brake pedal was not as tight as usual (it was coming even with the throttle pedal, whereas I usually have to roll my foot down a little to heel-toe). The ABS was working fine. I also noticed that the 1st half of the brake travel was light, but after that it would get tight.

Did I pinch a brake line? Is my master or slave going bad?





Here's where it gets worse: The cause of all of these issues was this saturday's autocross, I went offroading at about 70 MPH (my shift from 2nd to 3rd in a turn unbalanced that car too much and I lost it on the runway at fort knox) and slid to a halt sideways in the grass. After that the 5/16's inch pin that holds the front left brake caliper on was no longer doing its job and I had limp home both sat and sunday. There was so much play between the caliper and the caliper holder that I rammed a 3/8 inch bolt in where the pin should go (it's very tight now ). I didn't think this was a huge problem because I've had the pin fail before and I figured that the caliper had been worn down and was finally too loose to hold with the 5/16's pin. Replacing the pin with the bolt is why I had the car up. The brakes were working fine until I replaced the pin, so saturday's spinout is not the direct cause of the brake problems.

Thanks as always,
Justin

 

This is just a guess - could you have a vacuum leak in the break system? "pedal goes to floor. comes up after running a few moments. different feel and pedal height" Won't cost you anything to look.
JMO
Glen

 

Thanks, I'll look into it. Should be easy to check.

I was hoping that I'm missing something obvious and someone would have a little lightbulb turn on over their head.

Having the pedal be soft for half the travel, then hard after that is something that rings a bell, but I can't remember which bell...

 

Maybe I'm misunderstanding you, but you can't just crank a bolt down in place of the pin. The caliper needs to be allowed to float on those pins. Otherwise you can bend/break the caliper or rotor if it only loads one side.

 

I agree. The caliper needs to float or it won't work correctly. I am wondering if the caliper in a fixed position caused the cylinder to extend to far to make contact with the rotor. This is why it is soft for the first part of the pedal travel, then stiffened up.

A vacuum leak would not cause the pedal to travel to the floor, only make the pedal travel harder than normal.

Good luck,
Dino

 

If the caliper is locked in position the brake pedal will have to travel farther to move the piston farther to contact the rotor.Just a thought. Tim

 

That solves it, now to determine if there's any way to rectify my problem without a complete front caliper/bracket replacement.

Thanks.

 

my wifes 93 has shucked the pins a few times autocrossing and I know of a number of other vettes with the pins that have also come out under hard braking/antilock active manuvers. Most of us have installed a grade 8 bolt loosely and double nutted it. effective and much cheaper than the pins/washers/and clips from Chevy.

Scott