Ok, I put on SS lines a few weeks ago and the pedal felt rock hard. Changed my pads at the same time. The screws LAPD sent me were too short so I later tried to replace the screws and I broke the head off 1 so the stock bolts went back in. Still felt good. Then I noticed a squeak so I pulled the fronts again because the little adhesive shim on the back of the pad was all bunched up. basically it was pulling towards teh front. Anyways, I depressed the calipers by hand fixed the pads and put them back togethe. Since I had not opened anything for air I didn't bleed them. Got to Houston this week for a track day and my brakes felt "funny" to me. Defintely not as stiff. After bleeding them they felt the same.

Basically the pedal seems like it takes a while before the brakes start to engage. Could the master cylinder be messed up. I'm a moron at this stuff. I can follow directions, but diagnosis of brake issues isn't my cup.

 

Did you bleed the brakes again? Compressing the pistons to change pads often lets air in resulting in spongy pedal feel.

 

I did at the track and they are still bad.

 

Big D,
Which "Screws" are you reffering to?
Which Brake lines did you get?
Which Pads are you using?

When you changed the SS lines, did you let the Master Cylinder go dry? You may have gotten air in the system and didn't bleed enough fluid through the system to clear that out.

Mark

 

I'm refereing to the banjo bolts
G-force from LAPD, they originally came with the wrong bolts
Dana Pads from ACDelco

 

Did they feel this way before or after your track day? Tapering of the pads will make the pedal go lower during a day of track type braking. Drives me nuts personally and I chased the squish until I finally came to the realization that this is "normal". I find after a couple of days of regular street driving, pedal height comes back as the pads wear the taper off of them. Hope you find your answer :yesnod: :cheers:

 

Okay,
The Bolts (screws) are for the banjo fittings. Are you getting any signs of fluid leaking?

As far as I know, the Dana pads are do not have the coefficient of friction that say the Hawk or PF "Z" pads do. Is it possible that you over heated the brakes at the track, which could have boiled the brake fluid? I'm just guessing here, but it is possible that your new lines don't have anything to do with the squishy peddle and that maybe it is just air in the lines from either the installation or overheating the brakes.

Not trying to tick you off, just solve the problem, so what method did you use to bleed the brakes?

I watched this one Porsche driver up at the track "Bleed his brakes" by attaching a hose to the bleed screw and cracking the valve open, and waiting for the fluid to run through. He must have been there for a half hour when I went over to see what he was doing. When I explained that he needed someone to press and hold the brake peddle down while he opened the valve and close the valve before the guy took his foot off of the peddle, he just looked at me with amazement. I could hardly help form laughing, but he then confessed that he had never been taught how to do it and asked me to explain the whole deal to him. Then I felt bad that I was about to laugh at him. We are now pretty good friends and his brake peddle has never felt better. :D

 

I guess I'm not being clear really.

I replaced the pads and lines all at once. After that the brakes felt great. Very stiff.

After that LAPD sent me replacement banjo fitting bolts because I got the short ones. I put them in and twisted the head off of one of them. put all the stock bolts back in. Bled the brakes and it still felt stiff and engaged quickly.

Then I noticed my shims were folding up on the front pads. Took the front pads off again (had to compress the calipers to do that) and fixed the shims and put them back together. Didn't bleed the brakes after that.

Then I noticed they felt squishy. This is all before racing.

When I got to Houston I decided to bleed them since I hadn't. I didn't see any bubbles after 3 pumps of the brakes using the old fashion, depress, open, close, let up method using the brake pedal. Went out on the track and they felt better, but still don't seem to engage until the pedal is down a ways. After running around on the track they do get progessively worse.

I'm using Motul so I'm thinking 5 minutes of short track time isn't heating the fluid up that much.

You think I need to do a full flush just to rule that out? With Motul that is expensive, but I can do it if someone thinks that would help.

 

It really sounds like you still have air in the lines. You may not have bled them enough to remove all air that possibly entered the system. Be sure the master cyclinder does not go empty while bleeding and be sure you have pushed enough fresh fluid through to clear any air that may be in the system.

 

Forget the fluid!
The pads are most likely tapered. I have seen it many, many times.
Put a new set of pads on and I will bet the firm pedal will come back.
Dave

 

So when you bled them after fixing the pad shim they felt crappy, right? What do you think are the chances that there was a bit of air in the caliper that got displace up into the hose? If that is the case, then it might be worth while bleeding that one corner. Maybe tap the caliper with a small hammer between purge as to get air to rise up in the caliper. 1/2 a pint would do it if there is air at the caliper or flex line at that corner.

Did the MC ever go really low while bleeding the brakes. Could you have drawn air into the MC? in that case you would need to bleed nearly a pint to fully flush that air out.

Check the caliper where the piston is for any fluid leak. you may have dislodged the seal when you pushed the piston back. I have seen this on other calipers, just not a corvette caliper.

When you originally bled the brakes, prior to fixing the pad, did you bleed through at least a pint of fluid?

 

thanks for all the help guys.

I didn't fully flush after changing the lines, although I did push quite a bit out of each line. I think since I have nearly a full pint of fluid (just barely less) I will just bleed the system. Anyone ever figure out how many pumps of the pedal it takes at each wheel to bleed that particular line?

I looked at my pads and they don't seem tapered. Again, they were firm, I then removed and replaced the pad and they weren't firm anymore. I just didn't know if I may have damaged something else compressing the pistons. I think it is just air.

Donald

 

Donald,

Here's one more thing you might want to try. You stated that the problems started after you compressed the pistons back into the calipers. I'm wondering if you might have unseated the pistons in the ABS system slightly. You could try getting out on a quiet road and get on the brakes hard enough to engage the ABS system. This should "re-home" the pistons.

Again, don't know if this will help, but it can't hurt (except your tires ;)).

Have a good one,
Mike

 

bigDvette - I don't know how many pumps, but I do know that it takes about 3/4 of a liter (750ml) to fully flush/bleed the system of old fluid. If you use less, you aren't getting all the old stuff out.
The sequence is Right rear first, then left rear, then right front, then left front.

I have no experience with what Vettedreamer's ABS thoery, but what the hell, it is worth a shot. Plus a full ABS assisted stop is kinda fun anyway. :D

 

Thanks guys, I'm off to bleed.

As for the ABS thing. I engaged ABS so many times this weekend racing time trials that I don't think I need to try that one again.

Thanks,

 

With that much braking you've bound to have gotten a decent amount of pad taper (as mentioned above). So, don't be surprised if, after you've bled the system, the pedal travel is quite a bit more than normal. However, once you've got the brakes engaged, it should be firm.

Did the bleeding help? (brakes, that is) ;)

Have a good one,
Mike