I recently bought a 69 that had very little brake pedal. The previous owner had just replaced the booster & mstr cyl before I bought it. I did not ask why they were replaced(stupid on my part). I assumed the guy did not know how to bleed the brakes. The brake pedal goes with in an 1/2" of the floor before the brakes will start to work(you sure don't want to be going very fast & try to stop it???)I have since replaced both the calipers, rotors, rr whl cyls & used 3 new, not remn mstr cyls. I have bench bled the mstr cyls, used a Mighty Vac pump to bleed the brakes, still no pedal, I have also used a pressure bleeder(30 psi) to force the air out, still not any better. The calipers have the bleeders at the top. Does anyone know how long the rod from the booster to the cyl should be & how about the rod out of the back of the booster?? The assy on the car now has 4 5/8" rod in the master cyl(The cyl has the deep hole, 1 1/8 bore). I also removed the round proportioning valve, no help. This car is a 4 speed,not sure its original set up, I don't know if the pedal assy is correct for the car, is there different year model that would physically fit, but not work properly?? Pleae help, Thanks

Sounds to me that either the master cylinder is faulty or there is a breech in the system somewhere. I have only experienced bad pedal with 1. bad master cyl. 2 bad wheel cylinder 3. air in lines 4. broken line or loose fitting. Take the rear tires off and check the backsides of rim for brake fluid. For $15 another master Cylinder is a good preventive maintenance investment as well as insurance. If it is not the master, move on.

I read your post again..It sounds to me you have replaced all possible parts which would cause this condition except for the master and brake lines..try a new master..I have even purchased them new and rebuilt and have had them go out soon after replacing. If the car saw little use after replacing, that can sometimes cause a MC to go bad.

I have read your question a couple of times and it looks like you have checked or replaced the master cylinder and wheel cylinders. One of the areas of concern to me is that when you try to source a master cylinder for a '69 with power front disc brakes, no one lists one. My '69 has power front disc brakes with a 4 speed manual. It is currently apart to be restored but the guy I bought it from encountered the same problem that you have described. He rebuilt his using a kit from someone and it basically did just as you have described. I have not attempted to rebuild mine yet - I have planned on sending it to one of the professional brake booster and master cylinder restorers because of access to the correct seals, springs, etc.

Have you noticed whether or not the front brakes stay "engaged" after you have pushed the pedal to the floor or do they release immediately and the pedal comes back up immediately? If they do not release immediately, take a look at the front flexible brake hoses. I don't really think thats what it is, but it doesn't hurt to double check.

I think that you probably have a master cylinder problem but have you checked the booster? I am very suspicous of the guy telling you he replaced both. What happened to the originals? Like I said earlier - I tend to think that parts are not readily available for a '69 with this brake/trans set up.

I plan to go up to the attic and measure the brake rod for you, but I need to move some stuff. Maybe later tonight or tomorrow.

Good luck. Let us know how it turns out.

Tom

Tom, I replaced the brake lines today with braided steel hoses, no improvement. The pedal does return as soon as you release it & the discs don't have much drag when I let off the brake. I did have a shop that rebuilds boosters check it & they said it was fine. They also said the rod from the booster to the mstr cyl appeared to be correct, but could not give me any lengths?????

Thanks, Danny

Danny,

I pulled my power booster from the attic tonight to try and measure the rod for you - but no luck. The rod is part of the back side of the booster and I do not have correct tools to disassemble.

I checked my repair manual and it references a different booster than other Pontiacs of the same year but on the exploded view of the master cylinder they reference the Tempest and Firebird together.

If you send me your email address I will be glad to try and scan the pages to a Word document and email them to you.

Good luck!

Tom

Sounds like it's definately the rod. The previous owner may have interchanged the incorrect rod for this. Check the archives from the Firebird-L mailing list, this topic was brought up a few times on the list...

I'd bet that this IS the problem!

Good luck - Brett - 67 Drop Top 455!

I am not sure if this is what is causing your problem, but I have seen internal failure/collapse of the front brake hose(s) produce similar symptoms.