Just tried to move my 91 YJ 4.0, and it seems like the rear tires are locked.
Background: My water pump went out and I had it picked-up (flatbed) and delivered to my home. From the truck, the jeep was rolled into the garage (it rolled easily). I put the parking brake on and went to work replacing the pump/thermostat. Had to wait a few days for parts. 4 days later I put it all back together (no leaks, whewww!). Engine started right up, temp normal all systems go.
Then I put it in gear to take it for a test drive and my darling jeep wont budget but a few inches (letting the clutch out slowly) and it makes a sound like the rear brakes are engaged. Yep, I checked parking brake and it's released. Tried reverse, double checked gears and 4 wheel settings (2 wheel hi) and no luck.
More background: So last week, I finished replacing a few things: Clutch, Slave/Master cylinders, front left brake line, new 4" leafsprings and shocks. And a few weeks before that, I replaced the transfer case with one that came with a slip-yoke eliminator. Also replaced the rear drive shaft.
Up until the waterpump went, everything was running just fine. No brake issues, no clutch issues, no xfr case issues. We've been off-road (light duty) along dirt hills/roads and mud.
What could have happened just sitting in the garage? It rolled into the garage just fine.
The issue would seem to be one of the brakes locking up because of the long term application of the parking brake. The actual force required to establish the rear brakes isn't much. Therefore it doesn't take much to hold it on. When you released the parking brake the cable released the pressure but the spring mechanism in the rear brakes isn't strong enough to release the pressure on the brake shoes due to rust, likely.
Raise the rear end and take a heavy mallet and hit on the side of the rubber part of the tire. Then work it back and forth to see if you can get it to pop loose. If not, hit the backing plate with a hammer in a place that is flat. See if you can jar the mechanism loose to let the brake shoes come back from the drum.
If that doesn't work, remove the tire and strike the drum around the edge to see if you can jar the brake shoe loose that way.
Once you get them free, take off the drums and service the brakes. If the cylinders and shoes are good you can just replace all of the hardware, about $20 at O'Reilly's. I know because I just did that to mine when I rebuilt it from the frame up.
So, xfr case and transmission are dis-engaged. Left Rear (driverside) wheel is locked. Tried hitting it with a mallet, no luck. Just took the tire off and attempting to hammer on the drum. Nothing is breaking loose. We're going to bang on it a little more and see what happens.
So, I banged the heck out of the backing plate and even on the drum. No luck in breaking loose the pads. I noted the parking break cable is very loose and I take that as a confirmation that the pads are engaged (while the brake pedal is not).
I'm going to try and take the drum apart, but I'm guessing I wont get very far if the pads are engaged - right?
Chances are, you might have to go to the next step, remove your diff cover, remove the locking pin, the cross pin, and c-clip. This removes the drum and axle from the equation, you can now force the rear apart, breaking the pins that hold the shoes to the backing plate, you might have to replace the wheel cylinder if this rips the dust covers, or pins.
THIS IS A LAST RESORT MEASURE!
After you finally get it off, have your brake drum machined, or replace it, do this to BOTH REARS, and depending on the condition of the shoes, replace them too.
CHECK FOR LEAKS, a leaking wheel cylinder (if not broken) can quickly cause the brake shoes to stick to the drums like they are welded together.
Have a spring kit and new shoes and drums ready, remember new gear oil and diff gasket.
Well after reading the LAST RESORT MEASURE, i went and got (as was said above) a real MFH and what do you know, the drum came off and the pads literally crumbled!
Thank you: Xpress, ballistx, Steve79, and 2xs (great photo btw)!