06 8600 brake issue

Remember the kiss system. Keep it simple stupid. First thing is check to make sure the slack adjusters are properly adjusted. Your previous post make it sound like you don't know what a slack adjuster is, let alone how to adjust it. So snap a picture of the thing the rod from the brake can attaches to and we can tell you how to adjust it.

 

An inch to an inch and a half of applied stroke is normal. Those pots stroke 2-1/2" so there's plenty left. Auto slacks should only require manual adjustment when brake work has been done or because the slacks have worn out. It should not be done on a regular basis (unless they're manual ones but they are super rare today).

Those look like Rockwell slacks. On the bottom of that one in the picture there should be a little square adjuster. I think its 5/16" but its been a while. I highly recommend searching the adjustment procedure up on their website. I'll give you a basic rundown of how I do it. You want to chock your wheels, build air pressure to cut out and release park brakes. See that little round button on the back of the slack in the picture? Its a spring loaded lock pawl. You need to gently pry and hold it out (I find side cutters are much easier than a screw driver. Just don't bear down on it and damage it). Then turn the square adjuster so that the cam is turning the same direction as it would if the brake chamber was pushing on the slack. Turn until the brake shoes are tight against the drum. Visually confirm it through the inspection hole in the dust cover. If it helps, jack up that wheel and have someone spin it as you take up the clearance. The wheel will start to drag as you tighten up the clearance. When you can no longer turn the adjuster easily with a small wrench or ratchet, simply back off the adjuster 1/4 turn in the opposite direction and you're done. Since this sounds like your first time doing this I highly recommend marking the pushrod with a paint pen at the chamber as you go. Once you've done them all, apply the brakes and measure pushrod movement. As long as its 1" or so your ok. Anything over 1-1/2" I'd re-check the adjustment.

Key points:
-Brakes must be released with full reservoir pressure, wheels chocked. Check the reservoir pressure after every axle.
-If you turn the adjuster the wrong way, you will often start to pull the pushrod out of the chamber. Stop right away and simply turn the adjuster the other way. If you keep going, you can eventually pull the rollers out of the ends of the shoes.
-Be aware that you won't always turn the adjustment bolt the same direction every time. It will change based on position of the slack (fore, aft, underslung, overslung, left and right). Never assume you're turning the adjuster the right way just because that was how you did the last one. ALWAYS check to see the cam is rotating in the application direction and confirm that the brake shoes are tight to the drum before backing off the adjuster 1/4 turn.
-Take your time, don't rush. Brakes are critical to safe vehicle operation. Better to make sure you've done the job right. If at any point you are unsure about something, stop and seek assistance.

I assume no liability whatsoever.

 

He said he used a gauge and had 85 psi at the wheel with the slightest press of the pedal. If that's the case, it's probably the treadle valve.

 

I agree. He just seemed a little confused about brake adjustment so I figured I'd take a crack at that one.

 

What northenmechanic said. Except i prefer backing it off half a turn on drives and trailer and a tad more on steers. Just watch the drums to make sure you are tightening and not backing them off. Also grease those slack adjusters often. They like to freeze up if not kept lubed with fresh grease.

So step by step. Build air to governor cut out, should be at least 90 psi. Chock wheels. Push in yellow parking break button on dash. Build air back up. Grease the slack adjuster and scam bushings. Only 2 or 3 pumps with a hand held grease gun on the scam...you don't want that drum filling up with grease. Using a 5/16 open end wrench tighten the brakes all the way up. Using a flat head screw driver pull pawl back and hold while backing brake off half a turn. Remove screw driver making sure the pawl pops back in. Repeat for other 5 wheels.

 

Thanks for checking back in, @Fritzcoinc ! Far too often these threads hang in limbo, with no resolution ever posted. Nice to see one with the end result!