I am having a little bit of a problem stopping the car at the strip. My car traps 130mph+ and it slows down pretty good to about 40-50mph, then the pedal feels like it goes limp.

I have tried to 2-foot it and rev the car in neutral while braking to see if it was vacuum related (242/246 cam), but it doesn't help. I can put the pedal all the way down and the car doesn't seem to stop like it used to.

I'm using the Rotoworks drilled/slotted rotors from WS6 store and a set of Morse ceramic pads from Autozone. I was always pleased with the braking and thought it performed just fine in the past, but I've just noticed it being like this since my last track trip and a few times driving around town. A truck pulled out in front of me the other day and I hit the pedal so hard it went all the way down to it's stop, car didn't feel like it was slowing down hard enough, and I was only going 25-30. I barely got the car stopped in time.

Now, I've got pretty heavy wheels/tires and the car weighs 3900lbs with me in it. It seems like a long time ago I wasn't able to push the pedal to the floor, and also I've noticed that even when I slammed it down as hard as I could at 30mph the ABS didn't kick in. It has gotten worse and worse over time and I just got used to it I suppose.


What would you guys suggest?

 

Sounds like the pads/rotors are cooked. Look for a blueish tint to the rotors or a very polished/shiny finish. You could try doing just a surface refinish of the rotors and take a scotchbrite pad to the brake pads and resurface them, it may help. I would also recomend changing the brake fluid at this point and putting that superblue stuff in that has a higher boiling point. To check for a hydraulic problem, pump the brake pedal and then hold it at a stop. If it gradually fades to the floor, then you have a leak or bad master. Based on your description, I doubt it's hydraulic or it would be even worse and the red brake light would be on. I would say the pads and rotors are toast from trying to stop 3900lbs.

 

Hrmm.... The rotors don't look too shiny, but the fluid has probably been in there for 134k miles.

The pads/rotors only have about 3-4k on them, the car is a weekend warrior.

I may try bleeding them out and see if it helps, I'll also check the pads/rotors. Is there any special way you have to bleed the brakes?

 

When you bleed the brakes start=RR-LR-RF-LF. I guess you are going to gravity bleed them right?

 

I was going to apply pressure then crack the valve then pump the pedal then repeat etc. Same way I bleed the clutch. Any other suggestion?

 

Yep, but dont pump the brakes just push the pedal to the floor and hold it there until your helper closes the bleeder. You may have to do it a couple of times until a solid flow of clean fluid is all thats comming out of the bleeder.

 

Haha, yeah, I knew not to do that. Years ago I thought it would be a good idea to drain the clutch fluid by opening the bleeder and pumping it all out. Took me about 3 hours to get it bled again.

 

UPDATE!!!!!!!!!!!!!

So I took the rotors/pads off and buffed the **** out of them with surface refinishing disks and a 90* die grinder. I then bled the brakes until the cows came home. Still stops shitty. UNSAFELY shitty.

Could this possibly be a brake booster issue? It's been around since 1997 and has about 135k miles on it. My car is getting faster and faster and stopping worse and worse. Even at 25-30mph, it won't kick the ABS on if I jam the brakes as hard as I can. The car is trapping above 130mph and getting faster. I've got to fix this problem pronto.

I also thought about swapping out my ceramic pads for some more aggressive units. I'm not that concerned about brake dust anymore, considering I hardly ever drive the car. Would putting some non-drilled/slotted rotors help? Sugestions?

 

If you've bled properly and if you checked the rotors, calipers, and hardware all around, I would say that your master cylinder is shot.

 

wait, did you resurface the rotors on a brake lathe? I don't know about resurfacing them with refinishing disks. Also, you have drilled/slotted? I had a set (front and back) and eventually had cracks growing from the drilled holes, made the car shake a like a s.o.b. Swapped the fronts, still had a shake, had to swap all 4 back to the stock rotors.

Does the car pull to one side at all under braking?

You should still be able to lock them up though. Oh, and I don't know if you have ASR (traction control) but according to the GM service manual for an 01, it's RR then LF, LR then RF for trac control cars as opposed to the normal RR, LR, RF, LF method.

 

What brake lines are you running? Are the the originals? If those arent bad then i would go to the master cylinder. And if thats not bad then you could try the booster but i would think if its holding a vacuum then it should do its job just fine. If nothing else you could check that brake module just below the master and see if its bad.

 

So you've bleed the brakes, did you run at least 2 pints of fluid thru them? That's about what the system holds. FWIW, I bleed mine about twice a year, but then again I am autocrossing them.

There is no brake performance advantage with cross drilled or slotted rotors, it's purely bling and weight savings.

The brake pads you are using are find for a D/D, but you are trying to slow down a 3100+ lb vehicle from 140 mph, you probably should install a better pad ON THE FRONT ONLY! Try the Hawk HPS. I use the HP+ on the front of my SS. Don't put these on the rear or you will quickly find out what brake hop is, especially if you are running a shorter torque arm.

I don't think you have a booster issue because the booster is a power assist tool, and you complained that the peddle goes to the floor and is spongy. Think about it, if you depress the brake peddle with the car off, it's alot firmer vs. when the car is on. Think of it like power steering.

Check the caliper guide pins, they should all move in and out freely. The only resistance should be from the boots.

Now, I am not sure if the following could be your issue, but I had the exact same symptoms you are describing this year. I purchased a set of re-manufactured front calipers from autozone because I was too lazy to rebuild and clean mine prior to painting. The brakes felt spongy, but I thought just maybe it was me, not the car cause I hadn't driven it all winter. However I put about 12 L of really expensive brake fluid through the system and even bench bleed the master and it still didn't get better.

It wasn't until I almost put my car into a curb because it wouldn't stop did I actually take my issue seriously. I swapped out the autozone calipers for my orginal stock calipers and I'll be damned if the peddle didn't firm right up and the car now stops on a dime. I believe that the remans were fatigued and maybe spread so they couldn't develop the same clamping load as my original calipers, which only have 50k on them. So if all my above suggestions don't work, then consider replacing the calipers, but only use GM replacements. I believe you can get a good price on them at gmpartsdirect.com. Think of it as a small investment into saving yours own life.

You'll probably want to replace all the rubber lines in the system, they to do fatigue over time.

I hope this helped

 

Try a SSBC Residual Pressure Valve from AutoAnything.com
Its blue anodized & machined from aerospace-grade billet aluminum .

 

Keep the info coming guys! Hurricane Ike knocked my power out for 8 days, just now remembered about this thread.

Here's something else I remembered today. When I swapped in my 408 I disconnected the lines from the ABS block that run down to the K-member/suspension so I could drop it all out the bottom. The brakes were SHITTY when I got it back together, but I thought it was just because I was running a 253/263 camshaft lol. I guess I just sort of got used to them because now I have a much smaller cam (242/246) and they still blow.

I've been reading about air bubbles in the ABS block, and how it takes a Tech2 to bleed the air out. Is this true? Does anyone have any experience with this? I'm pretty sure the car stopped good before I yanked the motor and disconnected the lines.

 

I pretty much drained my system dry this winter and I was able to bleed all the air out the system using the Motive pressure bleeder after I bench bleed the master. Give that a try first before going all crazy with part swapping and dealer Tech 2 bleeds.

 

I was going to suggest using a Motive Power Bleeder and then I saw that post ^
I tried to bleed mine the traditional way but the pedal was still spongy so I ended up taking the car to the dealer to have them do it. The next time I needed to bleed them I used my buddy's Power Bleeder and that thing worked great! Are you still having the problem or did you get it fixed by now?