trouble shooting drum brakes

[kevmic28]

I have an issue of the brake peddle moving too far when I hit the brakes and the truck doesnt brake very well. I have replaced the master cylinder, wheel cylinders, new brake hardware, new adjusters, I have replaced everything in the brake system but the drums. Bled the crap out of the brakes but nothing seems to help. I have no idea if the drums are original or not so they may be way out of spec but I need some ideas before I throw more money at it.
I have no signs of the wheel cylinders leaking either.

Im thinking a bad master cylinder or drums too far out of spec.
Any other ideas would be appreciated.

[brad_man_72]

Sounds like they need to be adjusted.
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[Sammy]

Agreed. If the drums are true then adjust them out more. Also insure the drums are clean where they make contact with the shoes. Sometimes they shoes need to seat for the drums after replacement.

[kevmic28]

They are adjusted. They feel better since I added the new hardware and adjusters but not good enough. Also this is something I have been dealing with since I got the truck in 2009.

[geezer#99]

Did you replace the m/c with one the same bore?
Do you have the brake rod that attaches to the pedal in the upper hole?

[kevmic28]

I have another MC laying around. I am going to swap them and see if it makes a difference.

[jptriumph650]

I Had alot of trouble with mine as well. Did you bleed the brakes in the sequence the books say. Plus what helped as well I made a bleeder bottle out a 1liter soda bottle and put some fluid in the bottle and a tube running from the bleeder into the fluid. It worked for me.

[geezer#99]

Originally Posted by kevmic28

I have another MC laying around. I am going to swap them and see if it makes a difference.

Check the brake rod first!
Bolt it to the highest hole.

[kevmic28]

Originally Posted by geezer#99

Check the brake rod first!
Bolt it to the highest hole.

Forgot to say I have a booster on it. All I did was swap masters on the booster.

[kevmic28]

Also checked the brake rod. Its in the only hole in the brake pedal.

[1972SUPERSB]

I am wondering about this too. My pedal seems to go to far and I am thinking the drums need to be adjusted more or brake pedal needs adjusting.
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[Boog]

If the truck was like this when you bought it maybe it had the wrong master cylinder on it at that time. The drum/drum master cylinders are different than the disc/drum master cyls.
Excessive pedal travel is most usually caused by brake shoes not adjusted close enough to the drums.
Even if the drums are worn past spec adjusting the shoes out to it will compensate for the extra travel.
I adjust the shoes until the wheel stops turning to seat them then back off until the shoes just barely touch the drum.

[cdowns]

Originally Posted by kevmic28

Forgot to say I have a booster on it. All I did was swap masters on the booster.

if you dont make sure the rods are adjusted with the master cylinder and booster as they tell you in the GM factory service manual the brakes tend not to work properly

it is not a just boltup a new cylinder repair

[kevmic28]

Originally Posted by Boog

If the truck was like this when you bought it maybe it had the wrong master cylinder on it at that time. The drum/drum master cylinders are different than the disc/drum master cyls.
Excessive pedal travel is most usually caused by brake shoes not adjusted close enough to the drums.
Even if the drums are worn past spec adjusting the shoes out to it will compensate for the extra travel.
I adjust the shoes until the wheel stops turning to seat them then back off until the shoes just barely touch the drum.

If I have time tomorrow Ill try adjusting them again. Wont driving back and forth in forwards and reverse move the adjusters to the right point eventually?

[Boog]

Well moving backward and hitting the brakes hard is supposed to ratchet them up but as we all know self adjusters don't always work. The surest method is remove a drum adjust the shoes out to where the drum just drags when pushed back on then install the wheel. Now turn the wheel by hand and listen for the dragging sound. With a tool make any further adjustment through the slot in the backing plate. Move onto the next wheel.

[buckskins4ever]

I am glad you mentioned your Booster. Pull your vac hose attached to your booster and look for fluid inside it. It sounds like your booster has a bad seal and is not performing well enough.
I had the same issue right after installing a new master, and bleeding them.

[kevmic28]

I should have mentioned I had this problem before I installed the booster.

[LSUMurse]

I doubt this is the culprit, but I've heard of MC's being tempermental if you don't bench bleed them. Apparently, they can even be next to impossible to completely bleed if not done on the bench first.

[kevmic28]

I bench bled it correctly. I may have time tomorrow to work on it after work so I will swap the masters then and see if that makes a difference.