Master Cilinder on a '87 GTA

[umarth]

Hello,

I bought a 87 GTA last fall to learn mechanics, so as you can guess it has a bit of repairs to be done to it. So far I've been able to figure out (with a bit of research) how to fix/replace everything that I've tackled, but this one has me stomped: the brake pedal travel almost all the way to the floor before the cars starts to slow down. When pushed far enought, I have moderate braking power, but forget about hard stops.

I've pressure bled the breaks, had the calipers adjusted by a real mechanic and I tested to make sure that the booster does not leak (when pedal is pressed almost to the floor, but still has a bit of traval left, and held there, it stays there).

I spoke to a guy a few weeks ago that hinted that it might be the master cynlinder that is not the correct model for my car. He had had this very problem after converting his Firebird from drums to disks.

So my question is, how do I determine if my master cylinder is not the proper model? Anybody know the part number for an 87 GTA? Also, any other hints as the what might be the problem would be greatly appreicated.

Thanks,
-Jason

[Cashmunson]

check and see if you're 87 GTA came with disks already installed.

[Corey]

The master cylinder can be bad and still not leak. If one of the seals inside is busted it will just leak fluid into itself instead of pushing it down the brake line. If you are sure that there is no air in the lines I would just go ahead and replace the master cylinder.

You may also want to check the freeplay in the brake pedal. If you pull the pedal up by hand there should just be a barely noticeable (like no more than 1/4" at the pedal) amout of slack between the high point and the point at which the pedal engages the master cylinder.

Also, there is a problem with the automatic adjusters on rear disk brakes, so if you have rear disks, that could be a problem too.