I have a 1985 4x4 pick up with 35" mudders (25% tread fronts , 10% - bald rears). Proportioning valve is zip locked in the up position, which I understand will make the back brakes work more than normal as if I had a heavy load. The brakes worked fine other than occasionally the rears locking up, if I tried stopping too fast, due to the two factors that I mentioned above. My dilemma is I slammed on my brakes to avoid hitting a deer and now the brake pedal is hard and I have minimal stopping power. I should add that I have the driveline style emergency brake so I can't check the rear brakes by pulling the e-cable. Any ideas would be appreciated, thanks !

 

i'm guessing that if the brake booster went out the pedal would be hard to push.

engine off, if you push the brake pedal down, and hold it while you are starting the truck, what does the pedal do?

 

Thanks for the response. It fixed itself sorta speak... I took it for a test drive and pushed down a little harder than I wanted to, in fear of breaking something, but I needed to stop and as I was pushing down something popped and the brakes were back to normal. I'm guessing it might have been one of the cylinders stuck... ?

 

that is strange, hope that it doesn't come back!

 

Ya, it is strange but I'm just glad that I didn't have to fork out any money to fix it.
So far the brakes seem to be working fine,

 

you need to consider doing a brake upgrade. the stock brakes were designed for 225/15/75 pizza cutters.
when i went to 35's on my 81 i converted to Vented FJ rotors, V6 IFS calipers it was night and day improvement.'
I through in a dual diaphragm brake booster out of a turbo truck with a 1" bore master cylinder. I could stop on a dime. best bang for the brake mods you can do on a SA toy truck, well that and high steer to get rid of the crappy push pull steering