Need some input bleeding brakes....

**5abivt** · 10-10-2010, 01:34 PM

Here are the symptoms: when braking hard from 80-100 mph or even 3/4 pressure the car will slow for a few seconds and then the pedal will drop an inch and then in rapid succession the pedal will drop slightly further seeral times. I have ago stand on the brakes at this point to getvthe car to stop. I am insure if it's brake fade or contaminated fluid.

I just bled the brakes quickly with a friends help. It didn't seem like I was removing enough fluid as I had my friend pump and hold the pedal about 8-10 times per wheel ( when he held i opened the bleeder etc) and the fluid barely at the end was still close to the full mark. My pedal is prett mushy and there isn't very much travel. I went for a drive and got the brakes fairly hot with successive stops and I thought I was in the clear but surely enough on the last stop I was going to do the pedal went firm near the end (almost as if abs was working) and dropped and I had to Stand on it to stop.

Car is an 02 with no traction control. I am planning green pads and a full flush soon. Anyone experience anything similar or have Any thoughts or suggestions? I did replace the rubber boot in the brake master last month or so and within a day it had swollen to the point I was barely able to get it back on the cap and on the master.

**5abivt** · 10-10-2010, 01:35 PM

Holy iPhone spelling errors sorry

**Smittro** · 10-10-2010, 03:02 PM

Could be a few different things. I'd do the flush first and see. However if you're not running @ least a semi metalic pad you will experiance fade under hard breaking with cheap pads.. Rotor glaze could be an issue.. Bad booster, or master cylinder.. Issue with your ABS.. VACC leak coulds cause braking issues as well.. Some folks don't like full metalics because they sometimes chew rotors but our rotors are cheap so I replace them with every brake change and I use full metalic pads always... Imho try your plan first and go from there..

**Cutlass** · 10-10-2010, 05:31 PM

Sounds like it could be a bad master cylinder.

**5abivt** · 10-10-2010, 08:05 PM

Thanks for the input guys. I never considered the master. When I brought the car home and went over the fluids to check levels I found the rubber boot inside the brake master cap torn and expanded like 2x the size of the cap. i couldnt get it back on even. I had to drive like that to the GM dealer and buy another. $50 later and a short time later I took off the cap and almost the same thing. Any reason why the rubber boot would expand so much making it so it would barely fit?

Brake pads could very well be cheapos. i haven't changed them since I could see they had a ton of meat on them left and i never experienced this brake problem until I started pushing the car harder. I must say it's not fade like i've experienced before. Normally the fade I've experienced is pad fade where the pedal will still be hard and the car just doesnt want to stop. This time around its pedal fade it seems. the pedal gets mushy and the travel increases. So having said that i'm not so sure its the pads.

what are the symptoms of a bad master? When cold for the first 10 minutes of low speed stops etc I can get the car to stop really hard and even activate abs. I guess i should start with flushing the brake fluid...

**Cutlass** · 10-10-2010, 08:11 PM

Originally Posted by 5abivt

Thanks for the input guys. I never considered the master. When I brought the car home and went over the fluids to check levels I found the rubber boot inside the brake master cap torn and expanded like 2x the size of the cap. i couldnt get it back on even. I had to drive like that to the GM dealer and buy another. $50 later and a short time later I took off the cap and almost the same thing. Any reason why the rubber boot would expand so much making it so it would barely fit?

That can only mean one thing. Petroleum based fluid in the brake fluid. ie someone put engine oil, power steering fluid, or ATF in the master cylinder instead of brake fluid

**Cutlass** · 10-10-2010, 08:12 PM

In that case, you'll need to replace everything rubber in the system. Master cylinder, brake hoses, and all 4 calipers.

**5abivt** · 10-10-2010, 08:15 PM

Originally Posted by Cutlass

That can only mean one thing. Petroleum based fluid in the brake fluid. ie someone put engine oil, power steering fluid, or ATF in the master cylinder instead of brake fluid

Dayam... makes perfect sense. if the fluid boils would it reach the master? could that be a possibility? Anyone know how many bottles I would need to flush the whole system?

**Smittro** · 10-11-2010, 03:05 AM

Originally Posted by Cutlass

That can only mean one thing. Petroleum based fluid in the brake fluid. ie someone put engine oil, power steering fluid, or ATF in the master cylinder instead of brake fluid

Originally Posted by Cutlass

In that case, you'll need to replace everything rubber in the system. Master cylinder, brake hoses, and all 4 calipers.

This.....

If any of the old fuilds are left behind even in small amounts it will have the same effect you had before but over a longer time = unexpected/surprises.. Once everything has been replaced it should'nt take much to get the rest out of your lines.. however I'd flush the hard lines before installing your new calipers and soft lines..