65 Disk Brake Woes

[Dave McDufford]

Re: 65 Disk Brake Woes

Does you comment that "the brakes are deplorable" mean the front brakes do not work correctly?

The problem you seemed to be descibing is the rear brakes would work somewhat but would not release and return to their normal position (hot brakes). The fronts were being applied and releasing in a normal manner.

If there is an obstruction, as I suggested, that is preventing the rear pads from releasing rather than bad calipers, loosening the bleed valve will allow them to relase. If they can be moved, and the front brakes are ok, it is likely an obstruction in the line. If they cannot be moved it is the calipers.

If it is an obstruction you may need to disconnect the two ends of the line and blow it out with clean air. Which of course means you will need to rebleed the brakes.

If the front brakes are not properly working the answers may change...

Dave

[Daniel K.]

Re: 65 Disk Brake Woes

Dave,

The front brakes do release and I can not be certain if they are working correctly. I can see the rotors look bright and clean. It takes, in my opinion, an unreasonable amount of force to stop the car. That is to say, more brake pedal pressure than it takes to stop my 63 coupe. Just so you know, this car has 26K original miles and has sat for a lot of years. This too could be a part of the issue for the all the crud I purged from the brake system. These are the reason why I elected to replace all components (excluding the majority of the steel fluid pressure lines) on the car. If you don't mind, please let me know what your thoughts are on the front brakes as well. Maybe I should blow out all the lines....... Thanks again for your help. Dan K.

[Joe L.]

Re: 65 Disk Brake Woes

Dan-----

Keep in mind that even if the front brakes are working PERFECTLY, if the rear brakes are not, then you will have, overall, VERY poor braking performance. To have satisfactory braking performance BOTH the front AND rear brakes MUST be operating properly.

[Daniel K.]

Re: 65 Disk Brake Woes

Thanks Joe. You are correct. I've just called it a night on the car. I won't sleep well thinking about how to fix this problem. Tomorrow is a new day and perhaps a new way of looking at and assessing the problem. Thanks again for your help. Dan K.

[Eugene B.]

Re: 65 Disk Brake Woes

Dan,
If there is a line obstruction, perhaps you could find it by getting a large syringe and injecting brake fluid from the back, forward to the master cylinder. If the fluid flows freely, then I would say that there is no obstruction. If it does not flow freely, then perhaps a compressed air blow out would be in order.

Many years ago I bought this brake syringe at Bloomington. The originator said it was the hot setup for filling the brake system from the caliper bleeder screws forward to that all the air comes out in the master cylinder and no brake bleeding is required because there is no air in the system.

Good luck with your brakes. I'm going to install my '65 brakes soon and don't want to go through what you're going through.

Gene

[Wayne W.]

Re: 65 Disk Brake Woes

You can tell if there is a line obstruction if the caliper bleeds normally or not. You should have good flow when the bleeder is opened. Another check would be to turn the wheel and note the resistance, then press the brake. Let off the brake and check the resistance. If there is an obstruction, the turning resistance will hold even after a time.

If you cant easily push the pistons in and out with the bleeder open, there definitely is something wrong with the caliper, or the pistons are cocked sideways and stuck. This occcures sometimes wheen the caliper doesnt fit correctly, which can be caused by a bent mounting plate. Did you or anybody remove the spindle with a Kent Moore tool? Most will bend the mount plate if they dont know what they are doing.

[Daniel K.]

Re: 65 Disk Brake Woes

Thanks Gene.

I'm going to work on the car this weekend (rather than yard work) to see if I can put to good use all of the suggestions given by all the folks that took the time to respond to these issues. I'll post what I did and if it worked.

Thanks again. Dan K.

[Daniel K.]

Re: 65 Disk Brake Woes

Thanks Wayne.

On bleeding the system, I determined that there was good flow of fluid to the calipers (at least I think there was). Once we were satisfied with pedal pressure, we went back to the RR caliper and "pumped" the brakes and then opened the bleeder and fluid would shoot into the collection bottle. We did this at all bleeder points in the system. I had read by using this technique, we could eliminate the little air bubbles that may be hung up around the pistons and therefore get even better pedal pressure.

I will be looking closely at the calipers today and cleaning all lines as best as possible. I have access to some catheters used in angioplasty and are just about long enough to reach through the longest fluid pressure line.

Thanks again for your help. Dan K.