so whats ur reccomendation on adjusting them? i just adjusted them not 700 miles ago, and that was to get the e brake working good. are the shoes to tight against the walls of the drum?

What can i change at this combonation valve?

 

The shoes shouldn't be tight against the drums, that will make your rear brakes lock up with any sort of firm brake pressure.

Block the front wheels.

Put the truck in neutral.

Lift the rear wheels off the ground.

Remove the rubber plugs on the back of the brake drums.

Using either two flat head screw drivers or a flat head and a brake adjuster tool crank the adjuster until you feel drag when spinning the drum.

Back the adjuster off until you don't feel any drag.

Replace the plugs.

Put the truck in park.

Lower the truck.

Remove the blocks.

Drive forward and make a complete stop.
Drive backwards and make a complete stop.

Repeat 8-10 times so the automatic adjusters can even out the brakes.


That is how the service manual says to do it and that is how I do it, it always works out good.

The service manual also says to adjust the parking brake but I've never bothered with it since my parking brake engages when the pedal is about half way down.

 

Do your drums heat abnormally during normal driving? If not, the shoes aren't dragging so they're not too tight against the drum.

I hate to admit that I didn't think as much about this as I ought to have earlier -- I was running behind for an appointment and should have just walked away. I apologize for that.

Have you had your drums turned, or at least checked to ensure that they're not out of round? An out of round drum will do the thing you're describing even with a weak system leading up to it. With your upgrade applying more force, an out of round condition that you got away with before might be enough to bite you.

That said, if all of your parts are perfect and this still happens, the cheap/easy way out is to install smaller wheel cylinders because the factory units are neither repairable nor adjustable. I don't know how street legal an aftermarket proportioning valve might be... and if you install one and don't adjust it correctly you'd just be putting yourself and others in danger.

My nickel bet is on the drums being out of round.

 

Thanks for the correction on my explanation.

I would hazard a guess that the proportioning piece of the combination valve is diverting too much to the rear for the larger wheel cylinder then.

I have a balance bar on the track car (with a custom AP Racing MC) and it was difficult to adjust. (Not to mention re-adjust.) This does away with the proportioning valve. It ended up needing to be driven and adjusted based on actual performance behavior to get it right.

But you would probably have the same hard-to-get-right adjustment issue on the valve if it is an adjustable type.

 

The anti lock system in these trucks pretty much sucks. If only one wheel is locking, the sensor can't see that......

 

ive never smelt them burning... but never actually felt them with my hand to see

ok, guess ill first adjust them and if that doesnt solve it ill look to the drums themselves.

 

should the drums get hot to the touch after hard braking? there is also a clicking noise in one of the rear drums now, is that the self adjuster?

 

Warm with normal driving. If you have a click or any other noise, something is not installed right or broken.

 

Mine were making a clicking noise then right before I popped the drum off to inspect them I heard a slight grind.
A spring popped off and half of the springs along with the adjuster were ground almost completely to dust, along with the pads.

 

i adjusted them and it was perfect, no wheel lock. then it progressively rebounded to being just as bad as it was, why wont it stay adjusted right?