Too much brake boost

[FickleFinn]

I have a 67 chevy shortbed that I put a 87 chevy TBI motor into.

I seem to have way too much brake boost as if not careful I would go out of the windshield!!

How do I reduce the boost or is there something else I should do?

[geezer#99]

Did you change your pedal ratio?
Manual brakes have a 6 to 1 ratio and you need about 4.5 to 1 for power. Drill a hole in your brake pedal and move the brake rod down about 1 1/2 inches.

[FickleFinn]

Thanks, will do when the weather gets a bit nicer!!

[elf w/capital T]

haha that's crazy, I put power brakes on mine many years ago and felt the same I laughed in astonishment of how well they worked and just got use to it. but yeah try adjusting the pedal rod down a bit...? good luck...

[57taskforce]

Man I don't think I've ever heard some one say the brakes work too good. It's always the opposite!

[SierraMtns]

Originally Posted by FickleFinn

I have a 67 chevy shortbed that I put a 87 chevy TBI motor into.

I seem to have way too much brake boost as if not careful I would go out of the windshield!!

How do I reduce the boost or is there something else I should do?

My truck was doing the same thing. I am working on going back to manual master with disc/drum.

Let us know if re-drilling the hole lower fixes the problem.

Thank goodness for all this rain. ha ha

[Craftsmen]

I installed the ECE drum to disc conversion, drop spindles on the front of my 1970 SWB. I also installed the power booster along with the new master cylinder/ perportion valve, nice kit by the way. I followed the instructions and redrilled the brake Clevis hole in the lever 1 inch lower, a bear to do in the truck I might add. When I took her for the test drive I dam near but myself through the windshield, LOL. The truck actually stops better than my 2011 Silverado. I was so used to pushing them pedal so had with the drum brakes to stop ( all the while praying no one was going to pull in front of me) it took a while to learn to ease up on the pedal. Best money I ever spent.

[JonnyC10]

Wish mine worked that good.

[SierraMtns]

Originally Posted by FickleFinn

Thanks, will do when the weather gets a bit nicer!!

So any updates? Did re-drilling a hole lower help?

[FickleFinn]

Sorry to be so late with the update!! Haven't worked on the truck in months. Today I moved the rod down @ 1.5 inches and it made a world of difference. Much better feel on the brakes! I may still need to do a brake adjustment to get it right as I seem to pull left.

[BC10]

I can absolutely relate to power brakes being to strong.

I had not installed my seat belts yet, but just installed the power brake system, pulled out of the driveway, gunned it down the street, stopped suddenly, and WHAM banged my big head right into the windshield.

I was so glad I didn't crack my windshield, my wife was glad I didn't crack my skull. What can I say, we have different priorities.

Glad you figured it all out, I might have to do some adjustments myself.

[Ruscal]

Many years ago I was redoing my 57 chevy power brakes. I replaced the brake shoes with some high friction type, and also replaced the powervac with the larger diameter diaphragm. The brakes were way too sensitive to control. I ended up keeping the high friction linings, but ditched the larger diameter power vac unit for the smaller one. Everything was good after that.
Russ

[LPoole]

Originally Posted by BC10

I can absolutely relate to power brakes being to strong.

I had not installed my seat belts yet, but just installed the power brake system, pulled out of the driveway, gunned it down the street, stopped suddenly, and WHAM banged my big head right into the windshield.

I was so glad I didn't crack my windshield, my wife was glad I didn't crack my skull. What can I say, we have different priorities.

Glad you figured it all out, I might have to do some adjustments myself.

step 1... check to see no one saw you
step 2... make sure the truck is ok
step 3... change your underwear
step 4... make sure You are ok

lol man I cant wait to get some good brakes on my old truck. ones I have now are pump and pray... soon