low brake pedal, 70 4 wheel manual drums

[70 shorty]

I did a search here, but pretty much every thread I saw dealt with disc brakes, disc brake conversions and/or power brakes. Mine is still the 4 wheel manual drum brakes. My pedal will go almost to the floor, but not all the way. I can not lock up the brakes either. I do not see any brake fluid on the inside of any wheel. At first I thought it was the front brake hoses, as they were cracked, so I guessed they were expanding. They are new now, and no difference. I need to replace the back hose just to rule that out. I have replaced the master cylinder as well, but that too made no change. I have bled the brakes and am fairly certain I got all the air out. I'm not loosing any fluid from the m/c. I still wonder if the replacement m/c is no good, and maybe I need another new one (or maybe was given the wrong one, as in one for power brakes as opposed to my manual brakes) Anyone have any other ideas to look for? On yeah, the truck used to stop fine (for a 4 wheel manual brake truck), but something has definitely changed.

[Steeveedee]

Do you know for a fact that your brake shoes are adjusted properly? Do you have manual or automatic adjusters?

[70 shorty]

Originally Posted by Steeveedee

Do you know for a fact that your brake shoes are adjusted properly? Do you have manual or automatic adjusters?

I don't know the answer to either. I was thinking it wouldn't be adjustment only because this situation started one time while I was driving, not over a period of time. I've never adjusted drums, but have researched it. I know on the fronts, as you spin them you can hear and feel both of them drag at one point in their rotation. Wouldn't that mean the adjustment it good on them?

[rockyrivermark]

I'm sure you bench bled the mc right?
I'm guessing you are aware of that.
Mark

[68Gold/white]

Originally Posted by Steeveedee

Do you know for a fact that your brake shoes are adjusted properly? Do you have manual or automatic adjusters?

X2
If your shoes are out of adjustment, you will not have a good pedal.
Checking adjustment will be first thing to do. Won't matter what type of adjusters you have right now. If they are not automatic you will have to pay attention to them in future to avoid the situation you have now.
A 70 should have automatic adjusters. If they are not present, someone has likely taken them off. You should be able to purchase all the automatic adjusters at a parts store.

[70 shorty]

Originally Posted by rockyrivermark

I'm sure you bench bled the mc right?
I'm guessing you are aware of that.
Mark

Yes, I did

[LockDoc]

-
You didn't mention whether or not you took the drums off and checked the brake shoes or replaced them. If not you should....

On the drum brakes, one thing I found on mine is when you put everything back together and adjust the brake shoes you can’t just adjust them out until they start rubbing and quit. You have to adjust them out as far as they will go and you cannot turn the wheel or drum at all. This centers the whole assembly in the drum. (I even tap around the drum as I tighten them to help them center themselves) Then you back them off until the wheel/drum just turns, and stop. If you only adjust them out until they start rubbing and quit, the first time you press on the brake pedal the brake shoe assemblies will center themselves and you will have too much clearance between the shoes and the brake drum. I also put three lug nuts on backwards to hold the drum tight against the axle on the rear when adjusting them.

I know it is a pain in the butt to try and hold the self adjusters off of the adjuster wheel while you back them off, but this is the only way I could get my drum brake shoes adjusted correctly.

LockDoc

[demian5]

Check this out:

https://auto.howstuffworks.com/auto-...drum-brake.htm

[hotwls13]

Jumping in here, hopefully this isn't a hijack. I also have a 70 GMC 1/2t all drums but mine are power. I have been working on wheel studs recently so my rear drum brakes have been exposed. My adjuster(s) appear to me NON self adjusting?? Or maybe they were put in backwards? The adjuster wheel is towards the left and doesn't sit against a lever. Is that right?

[demian5]

Originally Posted by hotwls13

Jumping in here, hopefully this isn't a hijack. I also have a 70 GMC 1/2t all drums but mine are power. I have been working on wheel studs recently so my rear drum brakes have been exposed. My adjuster(s) appear to me NON self adjusting?? Or maybe they were put in backwards? The adjuster wheel is towards the left and doesn't sit against a lever. Is that right?

Pictures man, pictures. And compare it to the other wheels. Answers are on the truck.

[hotwls13]

Originally Posted by demian5

Pictures man, pictures. And compare it to the other wheels. Answers are on the truck.

Haha, yeah I just look at a pic I have of the passenger side. Looks like the drivers side is assembled wrong. I'll fix it tonight.

[Steeveedee]

Originally Posted by hotwls13

Haha, yeah I just look at a pic I have of the passenger side. Looks like the drivers side is assembled wrong. I'll fix it tonight.

With a little finesse, you should be able to remove and replace that adjuster without tearing everything apart.

[BugzC10]

Originally Posted by LockDoc

-
You didn't mention whether or not you took the drums off and checked the brake shoes or replaced them. If not you should....

On the drum brakes, one thing I found on mine is when you put everything back together and adjust the brake shoes you can’t just adjust them out until they start rubbing and quit. You have to adjust them out as far as they will go and you cannot turn the wheel or drum at all. This centers the whole assembly in the drum. (I even tap around the drum as I tighten them to help them center themselves) Then you back them off until the wheel/drum just turns, and stop. If you only adjust them out until they start rubbing and quit, the first time you press on the brake pedal the brake shoe assemblies will center themselves and you will have too much clearance between the shoes and the brake drum. I also put three lug nuts on backwards to hold the drum tight against the axle on the rear when adjusting them.

I know it is a pain in the butt to try and hold the self adjusters off of the adjuster wheel while you back them off, but this is the only way I could get my drum brake shoes adjusted correctly.

LockDoc

X2...this is the old school way I learned how to adjust drum brakes

[Steeveedee]

I center the shoes by making adjustments and then stepping on the brake pedal. I don't like cycling the adjusters back after getting lockup, personally. It doesn't hurt them, but I feel my method is easier.