As a new member I would like to say hello and thanks for the information provided on this site. I have a few questions to ask as I do some work on my car. I have a 66 convertible which I put new brake calipers on about 1000 miles ago and switched to a fully synthetic brake fluid. Now when I go to stop the brake pedal is VERY hard and I have to depress it with all my strength to get the car to slow (even harder to stop) I have new brake pads and new DOT 5 fluid throughout. As I have had a seal go a few months back. Any ideas of what I could do? I am really not comfortable driving it this way.

Thanks for any comments,
SVXr

 

Welcome to Corvetteforum :D :D I'm sure someone will answer your question in short order....

 

Are you saying the brakes started giving these serious symptoms immediately after changing the pads and fluid? If not, then it may not be related to the work you did.

You didn't mention whether your car has power brakes... a bad power brake booster (or perhaps a leaky vacuum hose to the booster, or even a valve leak that lowers engine vacuum) could have this effect.

A bad master cylinder (internal leak) could also have this effect, if your front or rear brakes are failing because of the dual master. Touching the wheels near the hub after sustained braking from speed might give you a clue if only the front or only the rear hubs seem hot.

If the problem happened fairly suddenly, well after the work you did, I'd bet on the booster or M/C.

If not the booster or M/C, then either the caliper pistons aren't moving to their full travel, or they are AT their full travel under pressure and still not squeezing the rotor, or the rotors and shoes are so glazed that braking has little effect. Measure the thickness of the rotors to make sure they aren't thinner than specifications (sorry, I don't know the spec offhand). Did you have the rotors turned, or roughed, when you did this work? Did you buy name-brand or cheapie pads?

In any event, you probably ought to have a brake shop inspect the car before you kill someone!





[Modified by waynec, 8:10 PM 11/6/2003]

 

Thanks for the welcome, and thanks for the ideas. I re-read what I wrote and I did leave allot out. Honestly I can’t remember if it did it right after the new calipers or not? I don’t believe so but I must tell you that 1000 miles ago was probably 10 years ago. The brake calipers were replaced as well as the brake lines all the way to the master cylinder. The calipers and lines came in a kit ordered from Corvette America. I don’t drive it as much as I should and for the last two years when I get it out after winter the brake reservoir is low. I replaced the seals in one caliper but it looks like another one is gone—but I assume it could be the master cylinder that is leaking. The M/C has never been rebuilt to my knowledge. Maybe that is were I will start, thanks for the tips, SVXr

 

You didn't confirm/deny the car has a power booster. If it does, check for a vacuum supply at the check valve. If you do, I would suspect the booster is the problem.

If you have had brake fluid leak on your pads, you will also have no stopping power but it will not make the pedal unusually hard.

A flex hose can collapse and cause blockage in the line. This will give a feeling of a hard pedal along with reduced stopping power.

 

Sorry, It is not a power brake system. Also it is not the dual chamber master cylinder that is most commonly seen. Mine is just the little round copper one. Very simple, and everything up to the master cylinder is relatively new. So where is the best place to send my master cylinder to be rebuilt? I would take it somewhere local but every time I do I get taken advantage of. Or should I just buy the rebuild kit and do it myself?
SVXr

 

You mentioned that you replaced the braking system about 10 years ago. If steel brake lines were used they may have rusted on the inside, thus causing blockage.
This happened on my car about 5 years ago. The brake lines looked new on the outside but had rusted on the inside.

Good luck :chevy

Savin' de Wave :seeya Dave

 

If you have a high, hard pedal and the "copper-top" single master cylinder, it's probably not the master cylinder. What kind of new pads did you put on it? With manual brakes, the semi-metallic pads take a LOT of pedal effort - lots more than the organic OEM pads do. :thumbs:

 

:iagree:
Most of the other possibilities would give a soft pedal instead of firm like yours. Most metalic pads are intended for use in power brake systems and will perform just as you've descibed with manual brakes. Unless the car is used for road racing or a lot of mountain driving, standard organic pads will work just as well, or better. Fortunately, our pads are easy to replace and aren't very expensive. If the problem is metalic pads, it should improve some as they get heated. You might try dragging them (foot lightly on the pedal) for a few blocks to see if it helps.

 

Well I now have a list of things to check and more importantly an idea where to start. Thanks for everyones help, SVXr

 

Check the flex lines between the calipers and steel lines. They will swell and cause symptoms like you described. Its a quick and easy check.

Tyler