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| | | | Joined: Feb 2010 Posts: 54 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2010 Posts: 54 | I've had this problem before and thought I had it licked but I don't.
I have a 46 Chevy 1/2 ton with huck brakes, when I got it I rebuilt the master cylinder, the wheel cylinders, installed new brake shoes and replaced the hoses and the front drums. I also replaced the steel line running to the rear.
Now when I run the truck around town and warm it up the brakes slowly tighten until they completely lock up (all four wheels!).
The first time this happened I thought I had the brakes adjusted too tight and I thought the heat expanded the fluid and locked them. I readjusted the shoes and now its doing it again.
Is there something not releasing in the MC? Too much fluid?
I'm stumped, any help would be greatly appreciated. | | | | | Joined: Mar 2000 Posts: 784 'Bolter | | 'Bolter Joined: Mar 2000 Posts: 784 | I'm no brake expert but it sounds to me like you have a problem in your MC. If I remember correctly there is a small port in the MC that lets the fluid flow back into the MC when you release the brakes. If that port is blocked heat can build up pressure as you have discribed. You might want to also check to see that your return spring is pulling the MC plunger all the way back when you release the brakes.
I'm sure others will come along with more info for you.
Good luck
George
Last edited by 46forme; 06/28/2010 12:01 AM.
| | | | | Joined: Dec 2006 Posts: 720 'Bolter | | 'Bolter Joined: Dec 2006 Posts: 720 | Have you tried pulling the pedal back with your toe? How do you get it rolling again, just waiting it out?
Like George said, if the MC piston isn't coming all the way back it's not gonna relase the line pressure back into the resivior and every time you push the pedal you'll increase the residual pressure in the lines till it locks up. This also allows the fluid to backflow as you get thermal expansion.
I've had that happen with 'Tater, the spring was too loose on the end of the return so it wouldn't release the line pressure, a new spring fixed that.
1956 GMC 370 dump " 'Tater "1970 VW Volksrod "the Black Bomber" 2007 Chevy Avalanche 2020 Jeep Cherokee Trailhawk, 2005 Harley Davidson FLHTCUI I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P
| | | | | Joined: Feb 2010 Posts: 54 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2010 Posts: 54 | The pedal will be solid (no up or down movement) so I can't pull it up to release the pressure. I have to wait until everything cools down to move the truck again, then it rolls fine. It is the heat that does something I just can't figure out what. | | | | | Joined: Jul 2001 Posts: 3,887 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Jul 2001 Posts: 3,887 | how close is the exhaust to anything brake related, like the MC?
Bill | | | | | Joined: Jan 2009 Posts: 1,644 Shop Shark | | Shop Shark Joined: Jan 2009 Posts: 1,644 | Read the post by rustbucket "brake issue"in general truck talk he had the same thing happen
Pete | | | | | Joined: Feb 2010 Posts: 54 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2010 Posts: 54 | Sqeeze I checked for anything close to a heat source no luck. Pete I read the thread, that gives me some things to check...maybe tomorrow. Thanks | | |
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