'65 Disc break problems

[Leland C.]

I have a recently acquired '65 coupe (manual breaks) that has developed a break problem unlike any that I have ever encountered. The breaks work fine until about 5 miles/10 minutes after the car reaches normal operating temp. After about 5 miles of driving, the breaks at all four corners begin to lock-up. If I shut the car down and let it cool for about two hours, the breaks unlock. Being totally confounded, the only thing that I could think of was that perhaps there was too much fluid in the break system, so I removed some fluid, but that didn't help. I appreciate any suggestions that anyone might have.
Thanks, Lee

[Jim T.]

Re: '65 Disc break problems

Leland since you say all "four corners begin to lock-up" , I have not read about this before. One brake location locking up is an indication that the brake hose to that wheel is ruptured inside and requires replacement. Replace all the rubber brake lines and eliminate the problem for many years.

[Leland C.]

Re: '65 Disc break problems

Leland since you say all "four corners begin to lock-up" , I have not read about this before. One brake location locking up is an indication that the brake hose to that wheel is ruptured inside and requires replacement. Replace all the rubber brake lines and eliminate the problem for many years.

Thanks, Jim. I'll give it a try. Like you, I wouldn't have been surprised if it were only one caliper, but, in this case, it is all four calipers! Lee

[Michael W.]

Re: '65 Disc break problems

Next time, take a wrench and loosen the two nuts that secure the master cylinder to the firewall. Pull the M/C forward and see if the brakes (not 'breaks') release. If so, there's a problem with the M/C piston not fully returning to release pressure.

[William C.]

Re: '65 Disc break problems

Another approach is to open the line slightly using the fitting at the master cyl and see if it releases pressure in which case you have a master cyl issue.

[Bill M.]

Re: '65 Disc break problems

I had the same problem on my power brake '65. There was some crud in the small port to the left in the picture. I used a paper clip to clear it. Make sure the seal is not covering the port; you could damage the seal.

[Leland C.]

Re: '65 Disc break problems

Thanks for all the suggestions (and the very sharp photo). Sorry for the misspelling. I'm out of town on business all next week, but I'll post the final fix... once I get to it. LC

[John H.]

Re: '65 Disc break problems

Leland -

Also, make sure you have the required brake pedal free travel (1/16" to 1/4") at the top of travel; if you don't, that will also cause the compensating port to be covered by the seal, blocking return flow of brake fluid to the master cylinder reservoir.

[Paul J.]

Re: '65 Disc break problems

...One brake location locking up is an indication that the brake hose to that wheel is ruptured inside and requires replacement....

It's the other side, Jim. The collapsed hose prevents the caliper on that side from getting full pressure, allowing the other side to brake harder, and causing the pull to the good side. I agree that when you have this problem, you should replace both hoses, if not all four.

Paul

[Jim T.]

Re: '65 Disc break problems

Paul my experience with a ruptured/bad original brake hose many years ago, over 25, with my 68 was with the caliper attached brake hose on the right front. Did not notice any difference in stopping the 68 one day, but what was wrong got my attention was after leaving a stop was when the right front wheel brake started emitting smoke because the brake pads had enough pressure from the released brake pedal to begin smoking going down the highway going home. Did not notice any pulling. Pulled off the highway seeing the smoke and waited until the caliper cooled down and was able to drive about 16 miles home. Planned my route home to avoid stopping, used gearing to slow when needed. All brake hoses were replaced years ago.