Sorry to tax your brain guys but this is strange. Drum /Drum application in my 53 Chevy. Dual Master Cyl- Fire Wall mounted / Power brake booster/ Automatic trans. * Recent build, have driven to "local (20-25 minuites away)shows few times, no problem. * I have done local 45 minuite shake down runs to see about eng temp etc, no problems PROBLEM - today, in 84 degree heat here in Pa I took it for 45 minute run with lots of local roads ,stop and go ,to a show. When I arrived at the show, I put in in park to pay entry fee . Then I put it in gear the car to enter the show and my brakes/something in my brake system locked up ! I had to inch my way in to parking lot ,dragging what felt like locked up brakes Emergency brake and cable was fine * My friends came over checked car and noticed 1) slight kink -bend in vacuum canister hose 2) felt there was not enough play in brake pedal and pulled the dual master off and adjusted the rod that comes through firewall and goes in to master cyl. to get desired pedal * We let car /brakes cool down for few hours at the show and drove the car home on highway to avoid lots of stop and go and made it home and the car was fine ??? I was told if I'm not sure /confident at this point to drive the car and recreate the problem. feel the wheels to see which are hot and diagnose from that point ** What are your thoughts ? What could this issue be of feeling like brakes were locked up ? I'm not sure the problem was resolved so I wonder if you all have thoughts/suggestions
What your friends did is the usual repair needed for this problem...especially on a new build. If the car had been on the road for several years and then suddenly started to have this issue other problems might be more likely. For example a damaged flex hose holding pressure almost like a 1 way check valve. Go for another long stop and go kinda run with someone following you if you are nervous. I mean you can't simply park the car and stop driving. The only answer is to find out if the problem is or isn't gone!
Sounds like the pushrod in the master...same happened to me, the rod is really sensitve and only takes a small adjustment to lock or unlock the brakes.
Your car is good to go -problem corrected? * As you can imagine ,it is really puzzling my buddies who helped with the build.
LBCD - We are puzzled as to why it did not happen on the few local runs we did and suddenly it happened now?
One other common thing on new builds is to have the brake pedal resting on the brake rod. Sometimes thats enough to keep the return port closed and heat then builds up and expands the fluid to the point the brakes lock up. The cure is as simple as a return spring on the brake pedal.
I have had a bad rubber brake hose do that also. Came home from a ride and the rear brakes were smoking. Bad rear brake hose between rear end and frame.
Bad rubber hose with a flaking particle inside can do that. Also- long long ago I had a very low mileage 57 Chrysler that suddenly started that. I had to drag a locked up rear wheel into a parking space. I found that backing up about 2-3 ft would release the stuck brakes, then I could move forward until I tapped the brakes, then it would lockup again. Reverse, release, drive forward until I tapped the brakes again - SCREECH. It turned out that a very small amount of grease got on the self-energizing brake shoes. A solvent cleanup and new wheel seal solved it. why be ordinary?
I have the same problem with mine, but it's only one wheel. I'm suspecting a faulty braided line I got from Speedway, but haven't had time to dig into it yet.
I would check the rod to booster adjustment. I had the same problem adjusted the rod and it went away. Does the pedal feel more firm after driving, compared to when just starting? Mine was great to start with then got worse as the drive got longer. I did some research on here and most people said check adjustment, and that was the problem. Tony
I agree with all the above. Drive it, if it does it again jack up the front try spinning BOTH wheels, then do the same on the rear. See if your locking up one end or both. If either or both ends are locked, while jacked up unbolt master cylinder. Did that release it? If not, then kick a bleeder loose on the end that's locked then see if the wheels spin. That will narrow your search on cause then go from there.
On my 56 Chrysler it was the rubber front brake hoses that were bad causing the front brake to lock up.Bruce.
It could be something as simple as the number of stops you made on the trips to the closer events or destinations as apposed to the one where it acted up. Maybe even just the stop and go into the event while in a line of cars waiting to get in and pay. Your bud did the exact thing that most of us would have told you to do and that is to adjust the push rod so there is a bit of clearance between the end of that rod and the bottom of the indent/hole in the piston in the master cylinder where it pushes. It doesn't have to be pushed in very much to cover the bleed back hole from the cylinder to the reservoir causing the brakes to stay on. Or maybe cover it just enough to where it won't bleed back fast enough and that is what I think happened in your case. In essence you were pumping up the brakes each time you hit the pedal on the way in. If you had rolled in and gone straight to a parking spot, left the car there for a few hours and got in and drove home without being in stop and go traffic it probably wouldn't have acted up noticeably.
If it still has problems after adjusting the brake rod, you might want to try a return spring on the brake pedal.
Ditto on the pushrod and return spring. I fought this exact problem. As LBCD mentioned, the rod adjustment can be very sensitive.
You have 2 adjustments that need to be right...pedal to booster rod and booster to M/C rod. Make sure your pedal rod has play with a good return spring, then try a couple of shims between the booster and M/C and see if that cures it. If so then that rod needs to be adjusted or shortened which will require separation of the booster from the M/C.
I think the bleed back hole is the key here, sometimes the hole is plugged by a piece of rust or something too. It acts just like a line lock if the hole is plugged.
Way back I bought a running/driving roadster, finished, debugged 1000+ miles I was told. ( Long list of stupid ****, some dangerous) Drove in city, stop and go and noticed front disc calipers were sticking. As I pulled into my first car show with it, got out and used a bleeder wrench to release brake pressure. A fellow noticed what I did and came over to talk and asked about problem, my reply was I had car 4 days and not sure why but seemed to build brake pressure, any ideas ? he looks under car and states, look at master cylinder to exhaust pipe clearance, 1/2 " was boiling fluid, made heat shield next day, 1 ******** item fixed, many more to go on that car, made a new friend that day that lasted for years. I have never built a car from scratch just fix as needed on what I purchase or trade for and understand some repairs/fixes will be nessary as these cars are not built by Pro's and some Pro builds that I have seen are pretty scary. I guess that's another discussion, definition of an Expert= someone on phone selling you something, Pro= a guy in business charging for his service, some good/legit, some full of BS and dishonest.
First idea matches what has been said by quite a few already; check the master cylinder push rod for proper length. Then check the wheel cylinders, even though you say they are new. I had a friend who had a '48 Hudson which developed a similar nearly the same as you describe. He had new wheel cylinders also but when we pulled the system apart to check everything, the cylinders had a bunch of glop inside each of them and that was what was preventing the pistons from retracting. Even though the cylinders were new, there was something inside them that was causing the malfunction. Once the cylinders were cleaned of all the goo, they worked flawlessly. Just a thought...
long ago i bought S/S calipers for a 66 corvette I owned, had a local guy change them out. first ride the brakes locked up. bled the whl cylinders to get home. couldn't figure out what to do, so I just put a single washer on each stud between the master and the firewall and never had another problem.
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