C50 Vaccum assist brakes

[fbaurley]

I have been having some problems with the brakes on a early 70s Chevrolet C50 grain truck. The pedal is extremely hard to push down, and when you finally get it to move it wants to lock the brakes, or stop you all at once. I think it may be something to do with the vaccum assit. It is not like the convential assist on a more modern vehicle, with the diaphragm mounted below the master cylinder. Does any one have any ideas? or is any one familiar with these trucks?

 

[jrobinson2]

Have you tried bleeding the booster, I assume you found it mounted to the frame behind the step on the driver side, the bleeder is on the top rear of the fluid end. I have also found problems with the plastic vacuum check valves (mine are mounted beside the master cylinder) there are also filters, usually mounted in front of the booster, if the lines to the filters are broken it can cause problems with debris in the booster. Check the fluid line from the master to the booster for kinks or crushed spots.

Check for good vacuum at the booster, Honestly it sounds like something sticking inside the booster, the last one I bought was around 300. 00

Jared