HELP - Parking Brake adjustment problem

I have a really strange problem with my parking brake adjustment. When I picked up the truck from the DRMO, the parking brake wouldn't grab at all, even with the adjustment on the apply handle screwed all the way in. No problem, I just backed off the adjustment on the apply handle all the way, crawled under the truck and cranked on the adjusting nut on the transmission until I had a good working parking brake again.

The parking brake worked well for quite some time. Then, over a time period of a couple of weeks, the parking brake got looser and looser to the point I had to crank the adjustment on the apply lever all the way down to the stop again. And it still got looser to the point there was hardly any tension at all when I applied the brake.

Yesterday I took the truck out and made two stops. At the first one, the truck would still roll with the brake applied so I had to leave it parked in gear with the engine stop pulled out, a practice I do not like to do. At the second stop, I pulled up on the apply handle and whoa, I had a full, tight park brake again!

I'm not sure what is happening. It seems something is loose somewhere in the parking brake system, but have no idea what. Anyone have any ideas of where to start looking?

Got this one! The self locking nut on the cable adjustment at the brake shoes has lost its self locking ability. Had this happen on a 2500 mile trip to OH back in the day. I cursed the truck the whole way but once I got home and started troubleshooting it, is was as simple as adding a second jamb nut. Also review the TM. There are several areas of adjustment for the parking brake shoes to prevent dragging. If not done correctly, the shoes, which should last for a long time, will wear extremely fast. The dragging will not be noticable and before long, no parking brake.

Been there, Done that!

would have proof if I didnt snap the end of the cable off!! It seams you shouldnt pop the clutch by mistake, with the brake on... in reverse... low range....

Snapped the end of the cable clean off!!

I concur with Kenny - the nut is lost it's ability to hold on. As for your mysterious appearing/disappearing parking brake yesterday, might be that one of the threads caught the arm the right way, and caused enough friction to act like that locking nut. Either way, my same problem was resolved with another lock nut, and some simple adjustments done with the help of the TM.

Matt

UPDATE 6/07/06

Ken, Mike, Matt -- I WISH it were something as simple as a stripped cable nut, but that isn't it. Yesterday when I drove it last, I had a good park brake with the adjustment on the apply handle knob turned down tight all the way. Today I got in it, drove about 20 miles, parked, and the cable was so tight I could barely budge the apply lever!

Drove it back home, crawled underneath, the locknut was fine and there was about 1" free play in the actuating arm on the park brake assembly. Went back up to the cab, backed off on the adjustment knob on the park brake apply lever, and voila!, had a perfect park brake with the knob turned back out to near full loose position!

OK, whats going on here? I see two possibilities:

1. Operator error. Perhaps, while setting and releasing the park brake brake I was inadventantly twisting the adjustment knob at the same time, gradually loosening the cable tension each time. This would explain the gradual loosening of the park brake over time that I noticed. And possibly when tring to correct the park brake adjustment I got confused and turned the adjustment knob the wrong way, loosening when I thought I was tightening it and vice versa.

2. Mechanical Problem. Perhaps something is loose and shifting position down under the cab, tensioning and releasing the park brake cable. I don't have any idea what that might be; I can't see anything that would act like that on the cable for now.

I'm not satisfied either possibility is correct. I'm pretty sure I was not at fault, but I can't find a mechanical problem either. So for now, I'll be happy that my park brake is working (for now), mark the apply lever so when I DO turn the adjustment knob I turn it in the proper direction, and hope the darn thing keeps working properly!

Duplicate posting - sorry

Lee, My experience was exactly the same.... the adjusting nut would spin either way when driving. Some times too tight, sometimes too loose...

Thanks, Mike. You've restored my faith in my sanity - what little I have left. Guess I'll adjust the park brake to where I want it, tape the adjusting knob so it won't turn on its own, and see what happens!

Just run another nut up the threads, and jam them....

Just checked my new cable, it appears to be 5/16"-18 or 24

OK, I got it, the second time around. You are talking about the adjusting nut down on the tranny, not the adjusting knob on the apply lever in the cab. Definately fine thread, must be 5/16"-24. I'll get myself a jam nut tomorrow. Thanks!

I think You should check for the springs that pull the parking brake off the drum when it is dissengaged and make sure all off the parts below move freely when the parking brake is not on. My cable was stiff butt,
the problem with min was the pivot points for the shoes was frozen and although mine still had the pulloff springs to move the shoes away yours could be missing,broken or disconnected.

Ken, Mike - You had the answer! Crawled under the truck today, I could spin the cable adjusting lock nut freely by hand. I adjusted it again, then ran a lock washer and jamb nut down to the adjusting nut and wrenched it up tight. Everything else in the park brake system looks cool and properly set, I hope this solves my problem! Thanks!

Not to sound too cocky but I knew that was the problem/answer.

Me too.... as I spent a few days chasing the problem myself.

Well all, I have a slightly different problem with my P/B. I have the lever, not the adjusting knob style. I've tried adjusting the top shoe with the top bolt, the nut on the cable end and have no real success. I've lubed everything and all parts move freely. However, when I tighten down things so the brake holds it won't release when I release the in-cab handle . I'm now at a bit of a loss.

big spring???

DR when you release the handle do you get slack inside the cab?

I say the spring from the outer shoe to the cab support has vacated.

I have a new spring on the outer shoe that is VERY stiff due to the newness. However, there seems to be some slop in the connections where the inner and outer shoes connect together. The zerks shoot lube into the joints easily and plenty of goo squirts out. Perhaps the pins holding the assembly are worn? The upper shoe moves back-and-forth about 1/2 to 3/4 of an inch (from front to back of the truck). The adjusting bolt does not always rest on the ridge in the center of the shoe either. I'll be pulling the radiator later today and the alternator tomorrow. While I'm doing that I'll get more specific about the symtoms I see. It's a bit frustrating and confusing trying to adjust the P/B when I'm not sure what could be worn out.