7/8 master cylinder or brake booster

[Thigh19]

I've got a 1 inch bore gm disk disk master cylinder.
GM metric calipers on front and 8.8 Ford rear.
Brakes work good but the pedal is very hard.
From what I've search on the Web I get 2 answers.
First answer is a 7/8 bore master cylinder and the second answer is a power booster.
I have limited real estate under the hood so probably a 7" single diaphragm booster.
I need some feedback or recommendations on which direction I should go.
Thanx
Thom

 

[fuzz]

If it aint broke, don't fix it!! If the brakes work good what is the problem? Usually a hard pedal is a bad booster, if you don't have a booster now, maybe we need more info?[S

 

[Thigh19]

No booster now, just a hard pedal. Just need a strong leg. Won't lock up the brakes

 

[soltz]

Dumb Question

Have you gone through the master and wheel cylinders , make sure every thing is clean and working smoothly? Hard is ok but it should lock them up if your really get on it.
My 2 cents worth
good luck with it.

 

[Yankee Transplant]

Hope you find an answer ... I still havnt got around to finding out whats wrong with mine .. Mine is the same way hard peddle no skid tire ..

 

[Ol Blue]

Smaller master or larger bore caliper and wheel cylinder. Either will increase pedal stroke but give you a softer pedal. Speedway sells oversize metric calipers and I'm thinking about getting a pair to get more brake in front. I have a firm pedal and too much rear brake bias.
Blue

 

[Thigh19]

All calipers and master cylinder are new and front calipers are speedway. Came with the front drop axle kit. Been told a longer pedal would help but don't have the floor board real estate for that option.

 

[Willowbilly3]

I'm running the cheaper Speedy master, no booster and it is adequate. My problem is not quite optimal pedal ratio and yours might be to. In hindsight I wild say 7 to 1 minimum and I have just over 6. 2000 # car, disc/drum. It won't quite lock up the tires on pavement but stops almost like a car with abs. I never feel like I don't have enough brakes.

 

[Old Iron]

1. If you used a factory pedal, you probably have a power brake pedal assembly on a manual system.
2. A lot of the time the brake pads are too hard. Try a softer more aggressive set of pads and see if that helps.
3. You can drill another hole 3/4" higher on the brake pedal arm to change the pedal ratio.
4. If you're using a proportioning valve, make sure it's centered too.
The back brakes don't need to slide the tires, they just need to assist the fronts.

 

[zzrodder]

Seems the problem is your master cyl and 4 wheel disc system was designed to work with a booster. I don't know if a 7/8" bore master will move enough fluid for a 4 disc system but it would give more pressure. Like has been said already, increased pedal ratio is the another possible cure.

 

[Thigh19]

Gonna do a 7" dual diaphragm booster. I'll let everyone know the results. Wish me luck

 

[oldblueoval]

I would highly recommend what was suggested about increasing your lever ratio on the pedal. When I set up the pedal on my 49 IH I put it at 6.9 to 1, right at the 7 to 1 rule of thumb. Same problem, acceptable brakes, hard to lock up and a stiff pedal. Moved the pushrod attach hole 5/8" and made a world of difference. much better feel and you dont have to hurt yourself to lock the wheels. I have the original IH drums in front and 10 bolt chevy drums in back with a 1" piston master[