Thanks in advance. A newbie style question that I can't figure out. Don't want to spend more money if I am just overlooking something. I have what I believe is a set of Juice Brakes from the late 40s, early 50s. Currently sitting on my 23 T-Bucket. Running a master cylinder from a 57 thunderbird. Coming off of the MC, I have a T valve that splits off, one line runs to the rear and the other to the front. The line to the front then splits off and goes to it's respected side. When I bleed the brakes, pump, squirt, pump and finally get a good pedal on the car I run into this issue every time. The front brakes stay fully applied (locked up) but the back brakes act as they should. I had one fella tell me that the line from the MC to the front T is bad. One fella tell me that the rubber hose brake line is bad. And another say just get rid of that dang headache. My question, as novice as it is, would the actual brake lines themselves be bad? Or since I don't have a traditional style proportioning valve coming off of the MC, I should get one?
If the rear brakes release that eliminates having the pedal rod ajusted too tight. That is usually the issue when someone thinks he needs to take all the slack out and in turn the piston covers the return hole from the cylinder to the reservoir. A few thoughts. Front brake shoe return springs either weak, wrong for the application or installed wrong. Back in the 70's when I was doing ten or fifteen brake jobs a week I'd often get one on Monday morning that the customer starts out "Me and ______ did a brake job on it on Saturday and now it doesn't work right. 90% of the time they had parts out of place. Restriction in the front brake line due to using a fitting with too small an orifice or a twisted line from tightening it up, kinked line from when you bent the lines. If both brakes are doing it it is probably in the line between the T at the Mc and the T to split the lines. Pressure from the MC could push though the restriction but it is very slow to flow back.
Thank you. I double and triple checked the brakes and made sure that they were installed properly. If I crack the bleeder valve, the brake cylinder releases it’s pressure and then I’m able to get the drums back on. The holes on those T’s are significantly smaller than the ID of the brake lines. I will look into finding some new T’s at autozone (hopefully) tomorrow and see if that works before I go changing out the brake lines.
One side or both sides of the front brakes? Old rubber flex hoses (from the brake slave cylinder to the rigid hose) are known to fail internally and prevent the pressure from off of the brake slave cylinder (this locking the brakes). First diagnostic: Loosen the bleeder valve on the slave cylinder and see if the brakes unlock. >> "Coming off of the MC, I have a T valve that splits off, one line runs to the rear and the other to the front." Is this a "T valve" or a "T fitting". I've never heard of a "T valve" - at this point a picture would help. EDIT: I see your reply now - disregard this reply
It does it to both front brakes. From the master cylinder there is a T (front to rear), at the front there is a T (left to right). The metal brake lines go into a rubber house which then connect to the wheel cylinder. If I get the brakes pumped and bleed, both front brakes stay locked until I crack the bleeder valve. Should note, This car hasn’t been on the road in the past 50+ years. I have put new wheel cylinders in the front due to horrible corrosion.
If you crack the line at your T on the master to the front brakes,does this release the front brakes? If so it’s in your master, if not it’s forward of the T .
It's the rubber brake hoses, you said the car hasn't been on the road for 50 years. In 50 years the rubber hoses go bad, even if they look good on the outside. Have seen this many times. Driving on 50 year old hose is dangerous even if the brakes work correctly.
If the rubber hoses are old, replace them. If the metal lines are old, you need to either replace them or check that they are totally clean inside. If they have any rust in them, it could be causing the same problem. And no matter what, also check the free play at the master cylinder push rod. It needs to have a little bit of free play, when the pedal is released. Someone mentioned and dismissed this as a possible cause, but you still need to check it.
I had the same thing happen on my 50 chevy styline. It turned out to be the small hole (you can see it by looking in the reservoir directly below the fill cap) plugged with rust. I cleaned it out with a small drill, and the problem went away.
I toss old masters right in the garbage if a car has sat for even 6 months. Change all hoses and wheel cylinders, look at the hard lines. Blow the old crap out of them with carb cleaner and compressed air. Then hang your new parts on the car.
Ditto Squirrel's comment Brake fluid expands with heat and if you dont let your brake pedal completely relax from the master cylinder, this could be the cause. I have personally helped two of my buddies resolve this problem on their cars.
Look at my thread on my 3 Window issues. Changed over to Wilwood discs from Buick drums and had the same issue. Two different master cylinders, new lines, new residual valves, new proportioning valve and I solved it by not using a vacuum bleed
If the master brake cylinder does not fully retract, the hole to the brake fluid reservoir is covered by the piston. The brake fluid can not return to the piston. As the brake fluid expands from the heat of braking, the pressure on the brake slave cylinders increases and the brakes will not release.
If I read his posts correctly, the brakes aren't locking while he's driving, they are locking up while he's trying to bleed them. And he's doing that with the drums not in place. He can't get the drums on after he's bled them, and he has to crack the bleeder to get the drums on. That's a problem you don't bleed the brakes without the drums installed. I'm not sure he has a problem at all, just not performing the bleeding process correctly.
Hmm, maybe. But how do the front brakes get stuck if the drums aren't on? I love a good mystery. A digital photograph or three would be wonderful
No, if there is a restriction only in the front brake line. Case in point, in about 1974 I bough a 57 Chevy Panel with a 327 that had 12.5 Jahns pistons, an Engle solid lifter cam 202 heads and a Corvette 2x4 intake with matching carbs. The truck would lift the wheels in a hard launch in first but run out of gas just before you shifted, then pull hard in second until it died out and pull hard in third. Turned out that one of the brass fittings in the line to the carbs had a tiny orifice intended for natural gas in a home. Threads and diameters were right so the PO used it. After it was swapped out for the correct fitting the truck would run heads up with a Honda 750 in a street race. I'm thinking that is what he has, a fitting with too small an orifice to allow the brake fluid to flow back to the master cylinder in a timely fashion. If not that it is check every inch of the line from the T to and including the T for left and right front brakes. The problem is between and or including the Tees
My guess is the brake hoses, it's been sitting a long time, with fluid in can make the hoses spongy inside, you can force fluid through with pressure but the return spring pressure on the shoes isn't enough to force the fluid back through the hoses. Found it on cars been sitting many times. Also double check Freeplay on pedal to be sure. Sent from my VFD 710 using The H.A.M.B. mobile app
Yes, I was using a motorized vacuum pump to bleed with. Just make sure there is no restrictions in lines and hoses first.
First things first, make absolutely sure there is FreePlay in the master cylinder rod when the pedal is at rest. Secondly, are there residual valves in the lines anywhere? Third make sure the drums and return springs and all the parts and the front drums are installed correctly.Are these self energizing breaks?
Thank you everyone. I was able to find someone who could make me a set of rubber brake lines. Got them put on today and everything is working as it should. Pretty happy. Now, to go post one more thread and hopefully not bother everyone with another dumb question. But this new issue, really is driving me crazy. Again, Thank you everyone for the input and help
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