The Stovebolt Site Forums The Parking Lot Big Bolts 49 6400 hydro-vac

Howdy all. My 49's brake system is a lil' suspect right now. When I first got her runnin' she had a tendency to lock the rear wheels. Hydr-vac was definitely working as there was a definite difference in eng running versus eng off. brakes were pretty touchy for awhile initially. I tried to adjust brakes in front and rear to balance them. But on start up rear brakes would initially lock. and then they would be a little smoother with running time. Now I get an initial lock and then my brakes take a lot more pressure to initialize then before. Like the vac isn't working. Much harder brake force is needed to stop her. My question is, do these trucks take a pretty stiff leg pressure to stop even when the vac is working propewrly. Or should I be able to just hit the peddle lightly to stop? Also, the air intake located at the hydro-vac is naked. No filter or connecting hose. Does this tube need to be routed to the air filter to the engine? Or just a simple filter at the source? I'm borderline tearing it apart and rebuilding it. But don't fix it if it aint broke? Appreciate all help. And sorry for the long thread.
1949 chevy 6400 dually 2ton
2speed rear end

Hy chebbydog, all the hydrovac brakes I've driven have been very easy to stop, anything more than a light to moderate pedal pressure will lock the rear brakes up. A simple test for hydrovac function is, run the engine for a bit, then shut it off and pump the brake pedal a few times, now with your foot pressing down on the brake pedal restart the engine, if the hydrovac is functioning properly the brake pedal should go closer to the floor when the engine starts. As to filtering the air, yes you should do that, the factory had a separate small air filter, but I can't think of any reason why you couldn't plumb it to the air filter, hope that helps.

Thanks a bunch Shop Shark. Will try today.If you read this. When bleeding Hydro The book says to do w/eng off. But should I bleed wheels in similar fashion? Or while running? Thanks again Shark.

Engine off for bleeding. If you have or can go to Keith Hardy's online manual site it will help to check it out. It takes lots of patience and if you can get a pressure bleeder that will help. Just make sure to keep an eye on the fluid level in master cylinder so you don't run it dry.

What model pressure bleeder are y'all using ?

I bought mine from Motive Products.
www.motiveproducts.com

I've had good luck with it.