parking brake noise problem

[undysworld]

I was experiencing a noise from the rear of my 712, especially off-road, though not neccessarily locked in. We elevated the rear end and found a knocking noise coming from the rear end, apparently where the parking brake assembly is. The noise only occurred with the rear diffs locked (this would make the center drive shaft turn in the brake assy) We removed the brake assembly (after cutting a hole in the floor to access the rear body mount bolt!!). The noise seems to have been the rearmost brake clutch disc rattling - it is a little loose on the splined shaft. The forward disc fits more tightly to the shaft. We also cleaned the entire brake assy and the 'pressure plate' faces. We reassembled it and adjusted the brake. The problem seems to be lessened, but my question is:
How much looseness is allowable in the fit of the parking brake clutch disc to the splined shaft? Is this a noise that people just learn to live with?
Any advice is welcomed. I'm just glad I didn't have to pull a wheel unit! Thanks, Paul

[PinzEOD]

<snip> (after cutting a hole in the floor to access the rear body mount bolt!!)<snip>...<snip I'm just glad I didn't have to pull a wheel unit! Thanks, Paul

I think I'd rather pull a wheel unit than cut a hole in the floor. What was that all about?

[Jim LaGuardia]

The rear body bolt is accessable from underneath the vehicle

[undysworld]

The body bolt is indeed accessable from under the truck, but the nut is sort of captured up in a recessed area. The truck bed is dented enough to make contact with the top of the bolt, so even a box end wrench wouldn't fit in there. The bolt was frozen solidly into the rubber body mount, and the open -end wrench on the nut wouldn't free it. Lastly, there are wires running through the recessed area, and the brake light switch to worry about when considering the torch. So..... I used a 1 1/2" hole saw to make an access hole. Regrettable, (very much) but up in Wisconsin (read rust-ville) you sometimes do what you have to do. I can get a steel plug which will fill the hole. All the other four body mount bolts came loose with the impact gun.

But about my original question: how much slop is OK between the brake disc packs and the splined main shaft??

[todds112]

Mine rattle or clank sometime. After tearing mine down and media blasting everything I know it's working well. I think it's just the nature of the design. They should move freely, as that motion is what locks it up. Likewise they have to be loose enough to let loose of the braking surface when the spring is released.

[undysworld]

Thanks to all for the comments.

PinzEOD: Perhaps in retrospect you're right - at least the truck wouldn't have a f***ng hole in it. I was worried that the 'mystery noise' might mean some internal wheel unit repairs, which we've not yet done. We've only removed a front one once to replace a seal and boot. I was happy to have the truck in and out of the shop in a day instead of......?

Jim: Have you ever had experience with this particular bolt being frozen? It was a real bear. Any advice on how I could have avoided my hole saw surgery. Thanks.

Todd: Thanks, we'd pretty much come to that conclusion too, that it's sort of just the design. It all seems to work just fine, both braking and release functions, so I guess I'll let it be.

Thanks again, Paul

[PinzEOD]

<snip>I was worried that the 'mystery noise' might mean some internal wheel unit repairs, which we've not yet done. We've only removed a front one once to replace a seal and boot. I was happy to have the truck in and out of the shop in a day instead of......?<snip>

Regardless of the method. you did get in there. Much better than giving up!