The Stovebolt Site Forums The Parking Lot Big Bolts 53 6400 Rear Brake Adjustment?

Ok guys need ya' to school me on how to adjust the rear bracks on my 53 6400.

Here's the background.
Over thanksgiving I figured I'd try to get the brakes working on this truck so far I've not been too worried about them just driving it around the farm and in the fields at the farm, as the handbrake stops it fine, and the regular brakes work consistently after 4 pumps. The truck hasn't lost any fluid since we got it. We went ahead and bled the system at each wheel as we figured it was just some air in the lines. It had a little but all of them bled out fairly quickly and none of the bleeder screws were stuck.
Near as we could figure maybe the brakes hadn't been adjusted in a very long time and it was just taking 4 pumps to get them out to where they caught so I adjusted the fronts via the normal screwdriver in the slot method (they adjusted a long way out but then caught good). But I couldn't figure out how to adjust the duals in the back. I'm new to the big trucks so this is prob. simple and I just haven't run across it yet.

I did pull the drum on the front left and the pads look like they have alot of life left so I'm hoping this will be the quick fix.

Also the truck has a hydrovac and I've got no idea how it works or if it's working.

Thanks,
MONGO

There are 2 slots on each backing plate to adjust the brakes. I can,t remember which way to turn them but I think you pull the soon towards the axle. You should hear a suction noise from the hydrovac when you apply the brakes & the braking action should be strong if it,s working right. George

Some GMC's and Fords have a big cam bolt top and bottom on back plate. Loosen lock nut, adjust bolt/cam, tighten lock nut. There will be two seperate cyls to adjust on these. Get a brake spoon, much better than "driver" and has odd angles, easier to work with. Don't be suprised if you don't have to remove drum and work the adjusters some to get unrusted and moving. Adjust way out while drum's off, just enough to allow drum to slide back on.
Power booster will feel just like modern power brakes, plus when you let off, you should here a hiss or such at filter which is behind the rear seat in corner of cab. I drove mine w/out working booster for 5 years, just have to push a little harder on pedal. One day, the thing just started working after sitting half the winter, not sure why? Was much nicer to drive with a load after that, for sure.

I wondered what that filter was for back by the gas tank didn't make much sense to have gas tank vented into the cab but I haven't removed the tank yet to get it cleaned so didn't relize what it was hooked too. starting to wonder if maybe my supposed 4400 is a little heavier

kb3csw,

My 4400 has a hydrovac with the vent/breather behind the seat. Standard equipment on this size truck.


Stuart

thanks atomarc

Grumpy, great info. I just got a 49-6400 and it has no sign of any brakes. Looks like another total brake overhaul on this one, I doubt that the Flintstone method would work on this big beast-Oh and no emergency brake either.

The easyest way I have found to check the Hydrovac is to push on the brake pedal and then start the engine. If it is working you will feel the pedal fade down a little bit as the vacuum increases. Don't forget to add a small amount of 10w oil (3 in 1 oil should work also) to the Hydrovac canister from time to time. This keeps the leather seal soft. See the repair manual for instructions.

The breather cap found inside the cab is connected to the atmospheric side of the hydrovac canister. They were put inside the cab to help keep dirt from getting sucked in. My BIG trucks have this line connected directly to the clean air side of the engine Oil Bath Air Filter.

Mike