1978 ford f600
 

Hey guys newbie here. My father in law and I just bought this 78 ford f600 dump truck to haul some rock and topsoil around our property. The problem is the brakes. They don't work. We have replaced the master cylinder. All 4 front wheel cylinders. And bled all the brakes. Still goes to the floor on the first push. Builds up on the second. Im thinking the rear brakes need adjusted. My question is how do you get the drums off the rear wheels on this thing? Do you have to pull the axles? If yes how do you do that? Thanks for any help.

Moved to the Large Truck forum.

Ok guys im loosing my mind here. not that theres much to loose. I have got the wheels all off and adjusted. I still cant seem to get a solid pedal. i found out the brake booster under the cab was out. took it to get rebuilt. put it back in and still no pedal. turns out it was not rebuilt right. took it back again and they gave me a different one. put it on and still no pedal. turns out it is bad too. so I put a line in bypassing the brake booster. bled the brakes and still no pedal. goes strait to the floor. can someone tell me how to bleed the brakes correctly? maybe im not doing it right. thanks.

Could it be you just don't have enough fluid in the system? That F600 is a big truck, it takes a lot of fluid to fill up all those lines, hoses and wheel cylinders. You could have a leak somewhere else in the system. On my pickup the line to the rear brakes had rusted completely in half!

You probably know this, but to bleed brakes open the bleeder screw, have someone push and hold the petal all the way down, then close the bleeder screw, have them let the petal back up. Repeat that process until you get nothing but clear fluid several times in a row, then you can move on to the next wheel. Start at the wheel the furthest from the master cylinder, usually the right rear, then do the left rear, then the right front, then finally the left front.

When you put on the new master cylinder, did you bench bleed it too?

Sam

years ago we had the same problem with trying to get a firm pedal on these trucks and the way i found to work the best is to take a BUG SPRAYER a small 1-2 gallon one and put brake fluid in it and take the spray nozzle off and put some hose over the tube and connect it to the bleeder screw and pressurize the pump and then fill the lines till it runs out of the master cylinder ! do this on every wheel and it will work ! always start with the right rear , then left rear , then right front , then left front ! DONT LET THE PUMP RUN OUT OF FLUID !

Thanks that's exactly what im going to try. I already picked up s sprayer this morning.

I got everything put back together this morning. everything was empty of fluid. I started at the back passenger wheel. hooked up the pressure bleeder. pumped it up to 15psi. opened the bleeder screw. and let the fluid flow. I did get some air for a few seconds then it started with fluid(in the master cylinder).I let it run a little until I noticed no air bubbles. I then moved to the rear drivers. let it run and not much air came out. moved to the passenger front. not much air either. then the driver front. and the same not much air. I used a large surenge to suck the fluid out of the master cylinder so i wouldnt overflow as I did all this. I also did the brake booster last. the pedal still goes to the floor. there are no leaks anywhere. Im not loosing fluid that I can see. Anyone have any other ideas? thanks

now that you have fluid in the system try pumping the pedal and bleeding the system again , just dont run out of fluid !

update..... I did get the lines all completley bled out. but the pedal when strait to the floor. so I went to the local parts store and got some caps with the flare in them. I capped the line at the back of the truck on the frame rail before it splits off to the 2 rear wheels. instantly solid pedal. so that tells me i have a problem with one of the back wheels. so i hooked that line back up and moved the cap to the line where it splits off the rear eliminating the drivers rear wheel. hard pedal agian. that should have told me there was a problem with the rear drivers wheel. so I removed the drums and checked everything out. the lower wheel cylinder was blown out. I ordered a new one replaced it and bled the lines. but the pedal still goes to the floor. any other ideas? thanks

Recheck that wheel. Is that wheel cylinder the correct one? Are the shoes so worn or the drum so far out that the wheel cylinder blows out before solid contact is made?

Thanks for the response 85. I don't think the drums are that far out. I can adjust the shoes out to where they are dragging. The shoes are good. How would I check if the drum is too far out?

The drum will have the limits stamped into it. You will have to measure and compare against the numbers on the drum.

If the shoes are adjusted out to the drums, that would normally kill the possibility of the wheel cylinder overextending. But I would look at it again, as you have already narrowed it down to those brake positions.

F600 brakes
 

i have a 1977 f600 dump truck and have had the same issue before. i just kept bleeding the brakes after i was sure they were adjusted correctly. i would bleed them until there was no air. then id drive the truck around my property working the brakes. about 20 min trips. after returning id bleed them again and find air. after about three times i had 1/2 pedal the first pump. hope this helps. does yours have 6'' rear pads and dual wheel cylinders? if so do you know the part number for the lower wheel cylinder. i have been unable to find one for my truck. thanks

I also just got a 78 F600 Dump Truck. It needs a master cylinder. Where did you buy yours? Reply to joe.porter67@gmail.com
Thanks.

1977 F600: What size are the rear brake shoes, 15 x 5 or 15 x 6?

What is the AXLE code that is stamped on the Warranty Plate?

Besides needing the shoe size, I need the AXLE code to determine the rear axle type and weight capacity.

Drum brakes = shoes / Disc brakes = pads.