Extremely touchy brakes

[ohmsc10]

Just bought a 71. Truck has been converted to power brakes sometime in the past. I can tell by the new hole in the pedal arm. The brakes are so touchy I think I am going to fly thru the windshield if I don't just barely touch the pedal. Anyone have a solution?

[beautimus]

my guess is that you still have the non power brake calipers on it.
i think, there may be a difference in the calipers from power and non power disks. you could check with a parts store and see if there is a different part number for power and non power assist, just to be certain.

[OhOneWS6]

Check for contaminated pads and shoes. Grease on brake shoes = touchy breaks.

[ERASER5]

A bad poppet valve in the vacuum booster will cause extremely touchy brakes too.

I am pretty sure that the calipers are the same for power and non power brakes. The MC has different bore sizes to obtain the needed pressure for the calipers to work. A manual MC bolted to a vacuum booster would result in to much pressure too fast. As will having the rod attached to the wrong point on the pedal arm.

There should have only been 1 hole on the pedal arm. The 71 vacuum booster assembly should have leaver assembly on the rod and not a rod that goes straight through the firewall. That leaver assemble has a reducing effect on the pedal instead of a different attachment point.

A picture of what you have would be nice. Something has been changed. Also, in my limited experience, I have never seen a 71 disc brake without a power booster from the factory. It is possible I suppose. Maybe LMH can tell us for sure.

[crushermechanic]

my 71 was non power discs when i bought it. i converted it to power with a new booster and master cylinder. the calipers are the same. mine works great.

[ERASER5]

OK then. Does your MC/booster have the linkage setup?

[crushermechanic]

yea i put the linkage i pulled off a parts truck.

[Shyguy]

My '71 is also a non power disc brake setup from the factory and it works so well I see no need for power brakes.

Of course I am an old guy that grew up with vehicles that did not have power brakes, lol.

Heck when I was just young boy we had an old F*rd car that you had to run the slack out of it, as my mom says to stop it. What she was saying was you better anticipate when you needed to stop and let off the gas and let it coast to a stop, it had a manual,lol.

Danny

[JRBECK64]

Have you thought about installing an adjustable proportioning valve? When I bought my 69 Short Step the back end of the truck kept locking up on me and I was about to install one and decide to waite until I figured out if I were going to install Disc Brakes on the back or not. Its an Idea.

JRBECK64