Lost brakes at the track

[Bill_Ritter]

I was at the track the weekend before last and lost my brakes. the pedal goes almost all the way to the floor and barely slows the car down at all.
I was launching the car using the E-brake and foot brake at the same time to build boost. i did this 3 times with no problem. the 4th time i did this i noticed the brake warning light stayed on, so i tapped the brakes (while going down the track) and they went to the floor! luckily i got the car stopped by using the e brake by the end of the track.
I looked the car over and didnt see any brake fluid leaks in the lines or the hoses, or bleeders. the fluid in the resovior is still at the full level. Could i have blown out my master cylinder??? is that possible to do by doing what i did?

 

[wagon]

Pull your drums. Are you running the oversized wheel cylinders? It sounds like maybe one of the pistons popped out and is no longer pushing out the shoe.

Brian

 

[Bill_Ritter]

No, im still running the factory size wheel cylinders. I replaced them with new ones last summer because the S-10 ones were too touchy for daily driving. When i was looking for leaks, I unbolted the slicks and pulled the drums off and everything in the rear looked good.

It feels like the little braking power that i do have is the rear wheels. (and its VERY little)

Thanks for the reply!

 

[salvageV6]

I lost the rears at the track this summer on salvageV6.

That was fun at 112 mph on a full run.

Fronts worked good enough to stop me and I always go to the last turnoff anyway....

Drove it home on the fronts too.

I had a large puddle under the car about 8 inches in diameter in the pits where the line was rotted heading to the back brakes.

No puddle sounds like an internal seal problem.

Blaming mine on the line lock, but better there than on the highway on the way home in a panic stop.

 

[Bill_Ritter]

Originally posted by salvageV6
IBlaming mine on the line lock, but better there than on the highway on the way home in a panic stop.

How would a line lock cause that? I have one too... mabey that could be what caused it?

 

[turbofish38]

It does sound like you have an internal leak inside the PM. That would account for no obvious fluid leaks.

Eric Fisher

 

[turbofish38]

Oh,and one more thing. Can you tell if the pump and motor are running constantly or does it run a little longer than it usually does before it shuts off. Possibilty the pump and motor are also on thier last legs. You might check into replacing the PM with a lifetime warranty unit from AutoZone as replacing the pump and motor or rebuilding the PM can be a little costly.

 

[Bill_Ritter]

Originally posted by turbofish38
It does sound like you have an internal leak inside the PM. That would account for no obvious fluid leaks.

Ok at the risk of sounding like an idiot here... what are you refering to as the PM? The master cylinder?

 

[Bill_Ritter]

Originally posted by turbofish38
It does sound like you have an internal leak inside the PM. That would account for no obvious fluid leaks.

Ok at the risk of sounding like an idiot here... what are you refering to as the PM? The master cylinder?

 

[salvageV6]

PM is short for powermaster brake system.

It is a pump and master cylinder and a bunch of other stuff all in one unit, should be on your car.

If not somone converted it to a vacuum system which should be easy to spot as there's no motor hanging under the master cylinder.