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Brake problems

cowboyupmarine

New Member
Joined
Jan 20, 2009
Messages
4
I have a 1973 Bronco and I have been haveing major brake problems with it.

I has drums all the way around. every part of the brake system has been replaced exept for the Juntion block. the brake pedal is hard to push in, I have not been able to get the brakes to bleed right and there is to much pressure in the system I've blown both wheel cylinders on the passanger side. Can any one point me in the right direcsion.

I don't know if it's the Junction block or the master cylinder or even a combination. Please Help
 

bknbronco

Bronco Guru
Joined
Jan 17, 2011
Messages
4,378
Loc.
North Metro, MN
if your blowing wheel cylinders then maybe the master cylinder is WAY to big. Not sure what else would cause that problem in a all stock manual drum brake setup?
 

Ranchtruck

Sr. Member
Joined
Feb 7, 2008
Messages
766
The bigger the master cylinder is, the lower the max pressure in the system will be and the higher and harder the pedal will get.

As you go smaller in master cylinder size, the piston and pedal have to move farther to displace the same amount of fluid. That gives you more mechanical advantage over the system so the pedal is easier and the brakes can apply harder because the hydraulic pressure is higher for the same weight on the pedal. The drawback is the pedal has to move farther, so it's a balance between pedal height and effort.

The blown wheel cylinders have nothing to do with overpressure. They were either old and worn out or damaged in installation if you just replaced them.

If this is a power brake setup, make sure the booster is getting engine vacuum. The pedal should be harder to push with the engine off vs the engine running if you pump it a few times in either situation.
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
maybe you have very strong legs. I'd agree you dont have a MC issue or a H block issue H block doesnt do anything except provide a place for the imbalance switch and to tie lines together.
Blowing wheel cylinders either means they were crapppy wheel cylinders or your brake shoes were not adjusted properly and your brake drums are about worn out causing the wheel cylinders to extend farther then they should be.
If you havent done so already adjust the break shoes so you have some drag when you turn the wheel then bleed.
 
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