well I got my truck back from a the shop today. I had the brakes converted to a power booster and master cylinder as far as stopping power, it stops far better. The issue I now have is there is very little travel in the pedal, before the brakes completely stop. anyone here have a suggestion ? I know it is probably in the set up somewhere.
I like the guy that did the upgrade, so this is more for my knowledge when I take it back.
Thanks

 

Do you know what the bore diameter is of the MC that was put on and, are the front calipers single piston or dual piston?

 

Not sure of the bore. The truck has 2.5 drums all around

 

The stock MC bore diameter for all wheel drums, power or manual brakes, was 1.00".

The MC for optional front discs on a '69 F250 with power brakes was 1.125". It's POSSIBLE a 1-1/8" bore MC was installed instead of a 1.00" bore MC.

A larger bore MC will have a very firm pedal with little pedal travel. A large diameter MC will move more fluid volumn but, will produce less output pressure.

A smaller bore MC will move a lesser volumn of fluid, will have more pedal travel but, will produce more output pressure for the same amount of force applied on the brake pedal.

Another possibility is there's a defect with the booster. Problems with a vacuum booster often result in a very stiff brake pedal.

 

Thanks ultra ranger. When I apply the pedal, it pulls down with very little pressure. I'll check the bore.
Any chance the rod length could cause it ?

 

Without seeing the booster, I don't know if it has an adjustable input rod (the rod from the brake pedal pin to the back of the booster)?

The tip of the booster output rod should be adjustable though. With the brake pedal in a static position (not being applied), there should be a very small gap (.005"-.010") between the tip of the booster output rod and the back of the primary piston of the MC.

If the rod is adjusted too far out, it will keep the MC partially applied, even when you aren't pressing down on the brake pedal. This will make the brakes drag and can make them lockup after driving a short distance.

If there's too much gap between the booster output rod and the MC, you'll have a long travel on the brake pedal before any significant brake force is applied to the brakes. It doesn't sound like the rod adjustment is the problem but, without actually being able to see/lay hands on the truck, it's hard to say for sure exactly where the problem is.