Drum brakes too tight after short distance

T

Thegeach

New member
Before I get to my question I’d like to say thank you to all who contribute to the forum. This site has been a wealth of IH knowledge and assistance.

My truck: ’73 Scout II 4x4, 345, 727 auto, Dana 20 transfer case, drum brake Dana 30 front, drum brake Dana 44 rear. No brake booster.

Problem: my brakes get very tight (hard pedal) after about 6 miles of driving. With foot off the brake pedal the resistance is enough to prevent rolling at idle but not enough to stop the truck. It's like I'm driving with my left foot resting on the pedal. When in this condition there is zero play in the pedal, it's tight in the up position and hard to press. If I park the truck for 30 minutes everything returns to normal, no undue resistance felt and the truck rolls freely in neutral. At no time is it difficult to stop. The problem seems to be too much tension but only after driving a bit.

History: my Scout had been sitting for years while I was living overseas. I went through all systems a few months ago and replaced several components. Drums were replaced up front and resurfaced in the rear. New brake cylinders and linings were installed at all four wheels and tension was adjusted. Fluid was changed and flushed though all lines- no air in system. At this point the brakes worked correctly. After a couple months of driving the master cylinder began leaking so I installed a reman from the local parts store. At this point the brakes seemed quite good considering they are unassisted drum brakes but after driving a bit (6-10 miles) the tightening problem occurred.

Thoughts: is this a bad master cylinder that is building pressure but not releasing it? Could the adjusters at the wheels be too tight and need more play because the master cylindar is new? I read where some vw guys had similar issues caused by heat/friction but don't know if that theory fits here. Any thoughts, experiences or suggested testing measures would be appreciated.

Thanks to all.

Geach
 
Make sure the pedal push rod is alowing the master cylinder to uncover the vent holes that you can see from the top in the bottom of the resevoir.
Is the fluid still clean?
One test you you to do. Drive it untill the tight brake condition exists. Loosen on front and one back bleeder (one at a time) and see if fluid releases like it's under pressure. Then see if it rolls easily but don't press on the pedal until you see if it rolls ok.. If it does you're going to have to back the push rod off untill there is some free play.
 
Ok, I’ve always said I wasn’t going to be that guy. You know… the one who asks a question, gets a response and then never tells everyone what fixed the problem. Well I’m late responding but came back to report it was improper brake light switch adjustment. I guess the old master cylinder allowed more brake pedal travel so the switch needed to be all the way in to function properly. With the new master cylinder installed everything was tighter and the switch was preventing the brake pedal from traveling far enough back to relieve pressure on the brake lines. It’s amazing what another half inch of travel will do for you. So I reset the switch depth and all is well. My Scout rolls freely and stops great. Thanks to those who offered suggestions and sorry for the late reply.
 
That's good to hear. Reading your situation, I am in the same predicament. My truck's been having this kind of problem just recently. I'll try what you did and see if it works for mine.
 
maurice.cowell said:
that's good to hear. Reading your situation, I am in the same predicament. My truck's been having this kind of problem just recently. I'll try what you did and see if it works for mine.
Click to expand...

Well, did it work for yours? It is really appreciated that when you present a problem you come back a tell us what works.
 
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