Shuddering brake pedal.

[TylerZ281500]

why do you have to put it in reverse to make the adjusters work?

 

[sewlow]

Running in reverse, then hitting the brakes causes your adjusters to ratchet up due to the way that the shoes grab the drum. For some reason this doesn't always work on these trucks. I've tried it several times, just out of frustration & a last resort. Sometimes it works, most times, not. Sometimes, just one side will adjust.
This always worked on my square bodies, but then they have adjustment windows on the backing plates. I only did this if I didn't have access to tools, or was just lazy that day.
Speaking of backing plates, give those a once over when you do your brake job. Make sure that they are nice & clean, & not cracked.
If your not replacing the drums, before you get 'em turned, drop 'em on the ground from about a foot up. If they ring like a bell, they're good. If they go 'clank', they're cracked. And you probably wont be able to see the crack(s) if they are.

 

[DGA1]

I've heard that too. I think having clean, well lubed adjusters helps.

I know my semi floating 14 bolt has rubber inserts in the adjustment windows. I've heard that you can knock the piece of metal out on the 10 bolt to get to the adjusters.

I'm not sure that picking up my drum and drop it like that will do anything good for it...

 

[TylerZ281500]

anyone have pics of how the rear dum adjusters are supposed to be, i never saw a setup like that before so i actually guessed the brakes work but the adjusters im not so sure of

 

[sewlow]

The older trucks do have the adjustment windows, but once you get inside these truck's brakes, you can see a provision of some type to knock out, but it's at the bottom of the backing plate, & the adjusters on these trucks is at the top of the backing plate, just under the wheel cylinder.
Yea, that's what I said when the ole man asked me if I had dropped the drums. "Do WHAT? Drop 'em? Are you crazy? Why?" So that's when he told me that that's how to check for a cracked drum. Between my uncle & him, they owned over 30 cabs at one time. He knows maintenance, & brakes on cabs are one of the things that was a constant in their shop. He can do brakes with his eyes closed!
Every time I do that, I shudder & cringe, but I've never screwed up a drum doing it.

 

[DGA1]

Good to know.

Adjusters are at the bottom of the brake shoe on the 14 bolt SF axle. I'm surprised that the 10 bolt is at the top. Both of my old '69 chevy's (c20 and a Impala) had 4-wheel drums and all of those were at the bottom as well.

 

[sewlow]

Every vehicle I've owned, up until a GMT400 has had the adjusters at the bottom.
Where the're located on these trucks is maybe the reason why they don't work like they should. Crappy design!
The brakes on these trucks never were very good from day 1. 'Consumer Reports' has issued a notice concerning the poor performance of the brakes on these trucks. Basically it warns people to be aware of the prob when looking to purchase.

 

[DGA1]

I think my drums work reasonably well, once again its a 14-bolt SF. But I hear ya on the breaking of these trucks. The pedal mushiness is still there, even after a full brake rebuild all the way around, but swapping to a 1-ton calipers and stainless lines she stops a lot better.

 

[canuckz71]

Is there a write up or a step by step on here on how to bleed the brakes for these trucks? Talked to my Dad and he said he's never bled the brakes on something with ABS

 

[DGA1]

Same thing as without... I'll look through the factory shop manual tonight and report back.