brakes! (pedal to floor)

[lytemup]

hello! just got a beautiful '81 w/18,600 miles a few weeks ago. the brakes were kind of 'mushy' when i got it, but now the pedal goes to the floor and almost no braking force is produced.
it has not leaked anything what-so-ever onto the ground since purchase, and the master cyl is pretty much topped off, so am i looking at a bad master cylinder here?

any ideas or diagnostic tips would be appreciated! thanks!!!

also, i've noticed zip products has a master cyl rebuid kit, anyone recommed this?

 

[Eric]

First of all, welcome to the CAC, we'll do our best to get you all the help you need. Browse around the site, there's a lot of info already here at your fingertips.

As for your problem, before investing in a rebuild kit, try flushing the system with new fluid. Though the symptoms you've described are the same as one would see with a failing master cylinder, it may also the result of years of moisture and crud built up in the system. Even if the fluid in the MC is clean, the rest may not be. You say your 81 only has 18,000 miles so it must have sat for a while at some point, do you know how often it was driven before you got it? Sitting is not good for these old cars and sometimes the brake problems can take a while to show up. Mine sat for off and on for ten years and after a good flush, the mushy brakes gave way to solid pedal pressure. Since then, I've had other problems but the fluid flush is an inexpensive place to start and may very well be the solution you need.

Try out the search button at the top of the page and you'll find lots of us have had similar problems.

Keep us posted and let us know if a flush fixes it for you. If not, my first bet is a master cylinder.

 

[lytemup]

thanks for the info, the car really hasn't been driven much in the last 10 years, so that sounds like a good place to start.
thanks again

 

[Yoda]

lytemup ~ Welcome to The Corvette Action Center Community ~

71Shark provides some good advise. Brake fluid in the master cylinder is misleading, it usually always looks good, once you start to bled the calipers you will probably see quite a difference in color on consistancy. Out with the OLD and in with the NEW.

Here is an old thread about brakes you may find interesting too: Brakes .

I would like to also extend an invitation to visit the L81VetteRegistry and here is a tech article from the L81VetteRegistry on Brakes

Welcome and enjoy the ride

 

[Nut]

Been there, fixed it....

Lytemup,

Had the same problem this year with my '81. Mushy pedal, no leaks.... What's up with this? As stated before, flushing the fluid (may) help. But if you do so, determine which caliper(s) have the air in them. Likely candidate....out of round rotor(s). Calipers are great for keeping fluid from leaking, not so good from keeping AIR from entering. How so? Likely a warped rotor. A warped rotor will cause the pistons in the calipers to cavitate. Even if the pedal exhibits no "pulsating" when braking, the rotor may still be warped. In my case I had a shop turn all my rotors (on their individual bearing assembly) to true to rotor to the bearing. Replaced the calipers after scuffing up the pad surface a little. Haven't had a single problem with well over 6,000 miles since. Brakes are perfect. Cost $150.00. I'd go here before I'd start replacing parts. Hope this helps.

Regards.......... Nut

 

[lytemup]

fixed

turned out to be two leaky calipers that let some air in. thanks 4 all the suggestions

 

[Eric]

Re: fixed

turned out to be two leaky calipers that let some air in. thanks 4 all the suggestions

A problem solved . Now go drive that Vette before winter comes calling.

- Eric

 

[rpounds]

If I might add . . . a common problem with C2, C3 Corvettes are warped rotors which cause the pistons in the calipers to pulse back and forth. As this happens, air is drawn into the wheel cylinders (calipers), in some cases causing disastrous brake failure. Bleed the brakes and everything will be fine - for a few miles. Then, you're back to the pedal to the floor. The only real fix is to turn the rotors, preferrably on the car. There are a few shops around that will turn the rotors while on the car. If your problem persists, I would seek out this type of fix.