strange brakes

[harold]

Gentlemen ,any ideas about this. Took the Cobra out today, first time in a few weeks, seems like it rains here all the time anymore, but anyway. First time I hit the brakes nothing, pedal went down a ways then got hard car would hardly stop. Came back home , no leaks and fluid was O.K. went out in the drive made a few stops got a little better. took it out and got up to speed , made a few hard stops, grabs alot at first and kind of eases up as the car comes to a stop. Usually a hard pedal will indicate a bad booster. Any ideas? thanks Harold.

[dscott]

Harold, It could be a bad booster but they usually don't start working again once they go bad. I would check the vacumn line to the booster to make sure it's not leaking. If you haven't driven it for awhile sometimes the rotors will get a layer of rust on them from sitting, that could make the brakes feel funny.
Don

[Double Venom]

Harold,
Do what Don says...but stay the heck out of traffic!

DV...Keep us posted-hey?

[TonyMadrid]

I don't know if you have power brakes or not. If you do, could be the booster.

Wheteher you do or don't have power brakes, what about blance/proportioning? If your using a proportioning valve, maybe you have to adjust the setting.

Whatever you do, I would at least bleed the system to be assured there is no air in the system.

Tony

[Excaliber]

If you DO have power brakes, indeed the vacuum unit is suspect: It's not getting it's vacuum quickly enough, or little or no vacuum was available? It's leaking somewhere, check valve, cracked vacuum hose, or just plain old bad unit.

Some other possibilities (especially if you DON'T have "power brakes") are:

The pistons in the calipers retracted to far back in there bore, while the car was sitting?

The piston cups in the master cylinder didn't seal right away (again due to sitting?) and the first pedal stroke or two was not effectivly building pressure?

Either way the end result would be a low hard pedal until the second or third stroke. The key here is, HOW low did the pedal go?

The symptoms described (low, hard pedal) would support such a theory. First stroke of the brake pedal pushes the pistons back into place, but the master cylinder piston has reached full stroke, it's hard, but cannot build up any more pressure. Second stroke (or third stroke) would apply pressure now that the pistons are in position closer to the rotor.

OR, second ot third stroke would establish a good seal in the master cylinder piston and pressure would THEN be available.

Ernie

This link just in from another thread! Excellent stuff here!

http://www.911brakes.com/