Power Brake problems

[rustykustoms]

Ok, I put a aftermarket 7" power brake booster and corvette style master cylinder on my 60. The problem I'm having is hardly any brake pressure. I've bleed them till I'm blue in the face. They do stop eventually, but it's kind of scary. Do I not have enough vacuum? I don't have any vacuum leaks that I know of and the engine runs great. Just not sure what else to do. Never had this problem before when installing a power brake booster. Help.

 

[LittleStar]

Those 7" boosters work OK on roadsters and other liteweight stuff like that but my guess would be that it's too small for your truck. Try a 9" booster instead.

 

[rustykustoms]

I don't think that's it. I've used 7 in boosters on 50's cars, and they stopped on a dime. And they weigh as much, if not more than my truck.

 

[dvalentine]

I don't think that's it. I've used 7 in boosters on 50's cars, and they stopped on a dime. And they weigh as much, if not more than my truck.

The 7 inch booster should be fine if it's working correctly.

The first thing that comes to mind is the thrust rod off the brake pedal assembly may be too short. Mark the rod when it's pushed in fully now. Remove the rod from inside the cab. Then using something longer, measure the distance when the test measuring rod is pushed ALL THE WAY in and mark that distance. If you can see that the test rod went in further than the rod that's in there now, THAT might be your problem.

The only other thing I can think of is if you used a rebuilt Power Brake setup and it was DOA out of the box.

dv

 

[verdell]

Ended up putting a 9 inch dual diaphram booster on my '60 fleetside..also had to modify/fabricate a rod. That might be part of your problem..good luck!

 

[rustykustoms]

I will check the rod depth. That's a good idea. Thanks.

 

[66 KUSTOM]

if rod depth turns out to be your problem, this may help. hehe

 

[dvalentine]

if rod depth turns out to be your problem, this may help. hehe

"... lasting 4 hours, seek medical attention..."

I'm not seeing the problem !!

 

[drabo]

Sounds like the thrust rod is too short. One sign that you booster is bad is if the brake pedal is hard to push down at first and then goes soft causing you to slam on the brakes.

 

[66 KUSTOM]

you definetly dont want to go soft when at high speeds

 

[billybones]

pwr brk problems

Did you buy the correct booster for your truck year like I did? See my pics under billybones. Thought of a couple other q's. Bench bleed master before install. If 4whl drums, do not install proportioning valve block that comes w/kit, only use that if front discs are used. If all drums, re-adjust all 4 sets of shoes. Note: I have had the great experience 2x of having bad masters straight out of the box during Camaro restorations.