I have been trying to get the brakes to work on my 75/79 F250 and i am stumped. The chassis of the truck is a 75 (i think) and has drum brakes all around. I have changed 99% of the brake lines, all four cylinders and have no leaks anywhere. I bench bled the MC and checked to make sure no fluild was leaking out into the booster. I then proceeded to bleed about 400ml of fluid out of each cylinder, starting with the one furthest from the MC.

After all of this i still have a brake pedal that goes almost all the way to the floor before engaging and when it does it feels like only the front brakes grab. I havent tested the brakes at any speeds over 20-30km/hr for fear that i will have no brakes at all. The booster seems to work since there is a noticeable difference when the truck is running.

At this point im thinking i still either have some air in the lines or i have the wrong master cylinder, the MC is from a 79, possibly even a 2WD, that would have been meant for front disc.

Is the MC for front drum alot different or different enough that it may be my problem?? Will a 75 MC fit my 79 booster?

Another puzzling fact is that when i bleed the brakes at any wheel, both resevoirs on the MC go down. I thought the 75 trucks only had a distribution block so im not sure how fluid could be transferring back and forth?

 

It sounds to me like your brakes are out of adjustment. I know when I tightened the rear brakes on my 79, the pedal got a lot stiffer. There is two ways to do this. The easiest is to put the truck in reverse get going a decent speed and push the brakes in to stop, (it will help to pump up a bit). This allows your automatic adjusters to ratchet and adjust your brakes out a little bit making is so that your brakes don't have to travel as far before they engage the drum. The second method is to take off the rubber plug on the underside of the drum, and tighten them manually with a flat head screwdriver.

 

then again it could be the mc. But tightening wouldn't hurt.

 

good call, i will try some more adjustment although i did adjust them so that i could hear a light rubbing on the drum at the time of the cylinder replacement. The truck has only seen a few miles since the initial adjustment. The brakes do work a little better in reverse, could this be a sign of needing adjustment?

 

I don't know if the brakes working better in reverse has anything with needing adjusting. But I would adjust them as tight as I could, then back off maybe a1/4 of aturn.

 

I would try a master for the specific application of your truck....

 

ya i agree i just wanted to know if there is a real difference between the two before i spend the $60-$100 on a reman. one. I dont want to spend the money only to have the same problem.

Jeremy

 

20.00 for reman.. 50 for a new one. These things are dirt cheap.

 

from who? all i got up here in kaanadda is PartSource and NAPA

 

Shucks/O'Reilly ....

NAPA online shows about 10.00 more for each, respectively...

Didn't see you were in Kanuk land....