This is not a traditional build but as many as there are on here I figured someone could help. My latest project is a 54 Chevy Truck. It's sitting on a 87 Dodge Dakota frame so the front brakes are stock disk from the Dakota. The drum rear end is out of an S10. Master and booster is on the firewall and came out of a 93 Caprice, disk/drum set up. I got the truck on the road a couple weeks ago and I have been puting around town working out the bugs. It stopped fine. The booster went out. I replaced it with one from a 94 Caprice. The next day I drove out the road and after 10 or so miles the motor started to stress. I slowed down to pull over and the truck almost toss me into the windshield. The brakes were locking up. I felt around on the rims and the front right would almost burn your hand it was so hot. It took some time but I got the truck home. I thought it was a stuck caliper. I went and bought one before ripping it apart. I took the rubber line off and no fluid came out. Didn't think about it much until I tried to bleed it. NOTHING! No fluid would come out. I took the rubber hose back off the caliper and had the wife push on the brakes. Nothing.. I thought maybe the hose come apart inside. I bought a new rubber hose and still nothing. Hard lines are all new by the way. I took the lines off at the master and would get fluid to come out of one line but not the other. I thought maybe it's the master. Went and bought one and just now put it on. Didn't help. It's doing the same thing. I'm stumped. Not sure if I'm over thinking something or what. Back brake will lock up if you hit them hard. Front is doing nothing. The front caliper was sticking for sure but now it's doing nothing. Did I happen to have a few problems happen at the same time? This thing is nickel and dimming me to death.
I do believe your problem is if you are still using the Dakota M/C with the Caprice booster. If so the booster to M/C pushrod is too long and keeping the brakes applied. If you are using the Caprice booster AND M/C the pedal to booster pushrod is likely too long. Quick trial fix for too long booster to M/C pushrod put 2-3 flat washers between booster and M/C on the mounting studs. If that fixes things you now know what to adjust. Ya just can't go mixing brake parts from diferent vehicles without knowing what you are doing and areas to check.
X2. It sounds like the master isn't bleeding back and it's just holding the pressure on the front brakes Posted from the TJJ App for iPhone & iPad
Worth knowing as well, Dakota brakes SUCK. The calipers on those sieze at the speed of light, After many comebacks I have begun replacing the calipers on Dakotas with brake jobs. Aftermarket ones seem better. They are cheap.
Are the '93 and '94 boosters the same, with the same push rod depth measurement? Do you have the fronts plumbed to the disc port on the master? Do you have a pedal return spring that fully retracts the pedal? The problem sounds like a bad bleed, along with the master pistons not fully returning past their comp ports.
Try a master cylinder for a 94 because it might be different from a 93,GM used to keep them the same for years but you cant count on that now.
It sounds like the master isn't returning, like everyone else has said, but about a year ago, I bought a faulty booster that would self apply. Strangest thing I ever saw, start the engine and the brake pedal would pull itself down. I doubt that is what's happening to you, but If you can't find any thing else wrong, check that.
It all worked great. The master is from the Caprice. Not from the Dakota. It was all 93 master and booster. Booster went bad so I bought one at a yard. It came off a 94. After I had these issue I bought a master for a 94. Looks the same. I didn't look up parts numbers. So the Master and booster is GM from the same year. As others said it sound like a push rod issue. I pulled the rods from both boosters. Old one and new one.. They are the same. I shimmed it, it didn't bleed. I removed the shims (washers) and went the other way putting washers on the studs to move the master away. Still nothing. As I said before I have been driving the truck without issues. I bled the brakes during the build and have put maybe 100 miles on the truck before I ran into this problem. The front caliper locked up. It was froze up good! I replaced it and did nothing else to anything. It wouldn't bleed. I took the rubber line off and no fluid. No matter how hard you pushed it. I followed that back to the master where I see it's not coming out. The brakes worked fine before the front caliper froze. That's why none of it makes any sense. Line are in the right place. Could I have bought another master with the same problem mine had? Seem highly unlikely. I have tried everything I can think of. I messed with it all day. If anyone can think of something I'm all ears.
Yes but I don't think that's it. The master's line is open above the proportioning valve and nothing is coming out at the master.
That is a symtom of the M/C piston not retuning fully. Won't let more fluid into the M/Cs bore. EDIT :I once managed to bend the piston retaining snapring insatlling a M/C . Would not let the piston return all the way =draging brakes.
I've owned 1st gen Dakotas and loved them but I did have a couple of minor brake qwerks. One time and only one time, after working on the brakes, the proportioning valve stuck to one side and needed to be re-set. This could be your problem. However in your post you mentioned the 2 things I highlighted that tell me that it could be a bad brake hose. I have had a hose go bad internally and act like a one way valve allowing fluid to flow in one direction. Because of this, one caliper would come out of the bore to apply the brake but not contract back into the bore enough to release the brake. At that time I had 1 wheel that was hot and, upon disassembly, had no fluid draining out. In the 16 years that I drove 1st gen Dakotas I only ever replaced 1 caliper due to pitting.
If it's the GM prop valve, it's damn near impossible to bleed them by the pedal unless you find a way to hold the reset button down.
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