I'm wondering what might cause a low brake pedal after I've been driving on the highway without using the brake for an extended period of time. Yesterday I took my truck out on the highway on the rare trip out of town and drove for about forty minutes without touching the brakes. When it came time to hit them at the first stop light, the brake pedal was almost to the floor. I brought the pedal back up with two or three pumps and they worked fine. As soon as I could, I checked the fluid level and all the wheel cylinders and lines for leaks only to find no problem. When I used the brakes in town(stop and go traffic)there was no problem, but after they hadn't been used for a while again on the highway(return trip), the pedal was really low and had to be pumped to return to height. I checked the brake shoes and drums on all four wheels and the fluid/lines/wheel cyls agian without finding any leaks. I did my own brakes about 18 months ago and haven't had a problem, but I rarely take my truck out of town. I know that heat can cause brake fade, but where would any heat come from if I weren't using the brakes?(and it was 35 deg. yesterday) What gives? Anybody else experience this? Thanks!
Sounds to me like the master cylinder seals are faulty, providing that nothing else is leaking. When you did your brakes did you replace the M/C? I know I got a bum one the first time I replaced mine, had to exchange for another!
I didn't replace the master cylinder when I did the brakes originally, but about six months ago the seal in the back started to leak. I noticed this because the brake fluid wass eating up all of the new paint on my firewall. Instead of replacing the seal, I replaced the whole m/c and had no problems with it until now.. I re-bled the brakes and changed the fluid, but I'm not sure that that was the problem, because I've only driven the truck in town since them, and the problem only seems to occur on the highway. Thanks, and best of luck with the '65! --TrustyyRusty
I would say that your Mastercylinder is bleeding by. On the Highway you are not keeping the brakes pumped up because they are not in use, like when you are in town. In town they are used more often and are able to be pumped up more often. I've had more than one time that I have had to take new or bebuilt mastercylinders back to be replaced because of this problem. Don't mess around with brakes, get another mastercylinder. The life you save may be mine! Nobody wants to see that cool truck on the back of a rollback.
Thanks for the help. I put a new master cylinder on and replaced the rear brake shoes and all hardware except for the wheel cylinders(They were still brand new and looking like it). This seemed to bring the brake pedal and tension back to where it should be. I'm ordering new brake hoses all around because my old ones look like they are about ready to pop. I know, Iknow, I should have done this long ago--but. . . I was wondering if there was anything tricky about putting these on or tricks to make this easier. By now I'm sure sick of brake work! Thanks again. --TrustyRusty R.K.
>I'm ordering new brake hoses >all around because my old ones look like they are about >ready to pop. I know, Iknow, I should have done this long >ago--but. . . Don't worry, I haven't been driving the old pile since this unpleasant discovery except to test what my other repairs and adjust them! I really don't want my jalopy to be a road hazard-
