Jon97Z

(I did search before posting this.)

Last night, I had the rear of the car up on jackstands trying to track down a rear end noise. I started the car and put it in drive at one point, when I noticed that rear tires kept spinning despite putting pressure on the brake pedal. (I understand that our cars have weak rear brake pressure as a rule, but I'm just trying to find out HOW weak.)

My rear pads are under a year old and the car does NOT pull to one side or the other when applying the brakes. The master cylinder and calipers have never been replaced either. They're all stock.

My question is this...when the car is in the air like that, even though the our rear brakes are weak...should the pressure (at normal rates) be enough to stop the tires?? I understand that the front brakes handle the majority of the stopping power, but it would seem to me that the rears should at least be able to stop the tires when NOT under a load.

Capn Pete

Could you not stop them at all even if you stood on the brake pedal?? Or are you just thinking that a little bit of pressure on the pedal should have been enough? Does seem kind of strange, esp. if you were pushing right down on the pedal!! I know I've had my car running up on stands, and I can stop the rear wheels no problem (although I can't say for certain exactly how much braking force it takes to do so ..... and keep in mind, I have an LS1, which has larger brakes front & rear).

Jon97Z

Yep. Stood on the brake pedal as hard as I could and the wheels kept turning. But we could hear the pads making some form of contact. Just not enough to stop the wheels.

Capn Pete

That ain't right!!!

Check your brakes!! Hard to imagine the pads are worn out in ~1 year, but who knows? Bleed them?? (air in the system)

What about if you pull the parking brake ... does it stop/hold the rear wheels?

Jon97Z

That, I did NOT try. I should have. I didn't think of it at the time.
Pads are still good. I could see the remaining pad that's left through my wheels and there was plenty there. It just seems odd, that both sides equally failed. If one side worked and one didn't, that'd be understandable. (Also more noticeable.) It makes me wonder how long I've been driving it this way, because there's been no noticeable difference in pedal feel.

I've never actually bled brakes before. Is there anything out there that makes the job easier?

rngilliland

This seems to be a common problem. My car does the same thing and there are several other posts about it. I have never seen a soulution to it. On one of the posts there is speculation that having the front wheels stoped causes the abs to limit the brake pressure to the rear wheels. I was going to pull my abs fuse and see if it made a difference but havn't gotten around to it. The problem seems to be unique to the lt1 cars or at least all the posts I have seen were about lt1 cars. I think the abs system was changed on the ls1 cars at the same time the brakes were upgraded. That makes me think there is a good possibility it is just a caracteristic of the lt1 abs and not a real brake pressure problem.

I have bled my brakes and abs module several times using the method in the service manual with no change. I have also used a pressure bleeder and vacuum bleeder with no change. I don't have any leaks or brake lights on and the brakes seem to oprerate normally except for the problem you describe. I have LS1 brakes on the front and rear now but the problem was there with the stock brakes also.