1990 k1500 rear end locked up?

[coalminer]

Ok, I have this truck and the other day while moving it, when I went to turn it around, the rear end locked up, and had to just about burn the clutch up getting it unlocked. So I started playing around with it a little, I can drive straight forward and backwards and it is fine, but as soon as I try to turn, it locks again. By now, there probably isnt much left of the clutch from trying to get it unlocked. Im sure its not the brakes, because the line that goes to the rear axle is leaking so the rear brakes are not being used at the moment. By the way, this truck has a 305 with a 5 speed. There is no sign of the fluid leaking out of the differential case. Has anyone ever seen anything like this? By the way, the gear ratio is GU6. Is there any place I can buy the parts for the differential or is it better just to replace the entire rear end?

[16th hippy]

not too sure about the RPO code for the rear end, but if it is not a locker or limited slip, then it sounds as if the spider gears are locking up somehow, or if it is, then could be that or a clutch issue in the carrier. replacement parts are available i am sure, if you have the tools to remove the axle bearings and so on, would be best to rebuild the one you have if the housing is not damaged. buying a used rear end could land you in the same boat you are in now in a few months. just to clarify, when you say it locks up, the wheels won't move at all?

[coalminer]

Yes, when it locks, the truck wont move at all, I can rev it up and pop the clutch and the only thing that will happen is the engine will stall. I have never seen a rear end lock like that, I didnt know if anyone else had seen anything like that either. Once it gets a little warmer I will pull the cover and take a peek inside and see what is going on. The bad thing is I really need to get it to my garage which is about a half a mile from where it is now. I was thinking about removing the rear drive shaft, locking it in 4WD and see if I can get it there. I just hope I dont screw something else up in doing that.

[16th hippy]

if you lock it into 4wd, GO SLOW. it will take some time, but don't try to hot rod it.

[777stickman]

GU6=3:42 gears. G80=Positraction. Since your truck is a K model (4WD) what leads you to believe the problem is in the rear end? I agree that's probably what it is and also what the "Hippy" says about the spiders and/or the posi unit (if you have one). Really need to get the cover off and have a close look. If that's where the problem is then taking the drive shaft out is only going to drag the back wheels to wherever you're trying to get to.

[J-Ri]

I had a posi and I broke the clutch pack and a gear-like thing on the side. I got a piece of that gear wedged in the spider gears and locked it up. I was blocking both lanes of the road I was on (pretty much HAD to move it), so I floored it and broke it loose. There was a clear indentation on the spiders, but it needed no repair and lasted 20k miles until I upgraded to a 14 bolt FFA. As far as I know it was still ok when I swaped axles.

[16th hippy]

Originally Posted by 777stickman

the "Hippy"

i feel all warm and fuzzy inside...rofl

[coalminer]

Originally Posted by 777stickman

GU6=3:42 gears. G80=Positraction. Since your truck is a K model (4WD) what leads you to believe the problem is in the rear end? I agree that's probably what it is and also what the "Hippy" says about the spiders and/or the posi unit (if you have one). Really need to get the cover off and have a close look. If that's where the problem is then taking the drive shaft out is only going to drag the back wheels to wherever you're trying to get to.

Yes, it is the 3.42 ratio as far as I can tell, but I will look for the G80, I am not sure if it is posi, would that be the 14 bolt rear end? This truck had to be a special order, has no A/C, but it does have cruise. Well, the first time it locked, I got out of the truck and was looking under it and I heard a noise coming from the rear end, and then I was able to move it again, the second time it locked (I was trying to turn the truck around in the driveway) I was not so lucky and had to rev it up and let out on the clutch, and it did finally let loose. Going straight forward and back is no problem, but trying to turn is when it locks. Im pretty sure its the rear end, but is there anything else that could case this? Transfer case maybe? I hope that by removing the rear drive shaft I can at least get it to my garage so I Can tear into it, the problem is I still have to get it turned around in the driveway, or back it out in the street and hope it does not lock again.

[coalminer]

I know I started this over a year ago, but I am still messing with this thing, tried to drive it today, got it out of the driveway and on the road, drove fine for 20 miles. Pulled into my apartment complex and then tried to back out of the parking spot and it locked again, so I messed with it and broke it free, then it did it again and now it is locked again, the passenger side rear wheel is locked up tight, the drivers side wheel will move and the front wheels are moving. But with the snow I am dragging that rear wheel, having a hard time getting it where I can leave it. Guess I just need to tear into it finally, I will post what I find.

[16th hippy]

still thinking spider gears, their main function is to let one wheel travel faster than the other on cornering, and that seems to be where the problem is.

[coalminer]

Well, it was the brakes after all, I have never seen brakes do that but when I pulled the passenger side wheel off, and pounded on the drum, it let loose. I pulled the drum off and everything seemed to be fine inside, but I pulled the shoes and hardware off, put the drum back on and have driven back and forth and it has not locked up again. My guess would be that the brakes were so far out of adjustment, that when I went in reverse it jammed the pads agains the drum. Thanks for everyone who tried to help!!!