Question about my rear diff...

[msggunny]

Ok, so first off let me make sure i am on the right track.

On an open diff, with one wheel off the ground it should rotate freely.

Correct?

So here is the deal. i was adjusting the brakes on Saturday and had one wheel up in the air and was trying to rotate it to set the brakes. It wouldnt turn more than 1/16th or so, i thought it was my parking brake at first but confirmed that it wasnt that or it being in gear.

I tried rather hard to get it to spin, but it wouldnt. This seems like either a "Locker" or something else is in it.

I then got tired of dicking with it and put the entire rear in the air and low and behold both tires would rotate, but in opposite directions like with an open diff.

Could something be up with my spider gears? I dont want to pull out the diff as it works fine right now.

No weird noises, no ratcheting, no jerking while turning.

Any ideas?

[Apis Mellifera]

It didn't rotate with one wheel off the ground because it was in gear (the main gear lever in neutral doesn't mean it's out of gear). With both wheels off the ground, the wheel spun in opposite direction, again, because it was in gear . What you described is exactly how an open diff works and is perfectly normal.

[daveb]

(the main gear lever in neutral doesn't mean it's out of gear)

Not sure what the bee guy is talking about. The only thing I can think of is that you are in 4wd hi or low, thus engaging the front output shaft and trying to turn the front diff as well, which with both wheels on the ground is unable to do so.

If you had a locker that was in the locked position then both wheels would spin in the same direction (or not spin in at all in your case).

MS, there are lots of ways you can end up in 4wd, if the linkage is frozen or missing parts or if you have the floors out.

Try to see if the front prop is trying to turn

rgrds
Dave

[Daurie]

I second daveb, if the gear selector is in neutral and the t case is in 2wd you should be able to move one wheel with the other on the ground. May take a little extra effort as the rear drive shaft, the t case and output shaft of the trans will be turning too. If you still have no luck put the t case in neutral and try. If you indeed have trouble then that will determine where to start looking. If all is normal with trans case in N then I'd look at the transfer case. If not then the diff.

[msggunny]

Forgot to mention, the t case was in neutral, the trans in neutral, and the front tires were chalked.

Its not stuck in 4wd, I checked it out already this weekend.

Thanks.

[Apis Mellifera]

Not sure what the bee guy is talking about. The only thing I can think of is that you are in 4wd hi or low, thus engaging the front output shaft and trying to turn the front diff as well, which with both wheels on the ground is unable to do so.

Yep, that's what I meant!


With both wheels of the ground, if they spin in opposite directions, then the dif is working and pretty much confirms it's open. With everything in N, I don't know what could cause the one wheel to not turn other than you may just have to try harder.

[daveb]

Hey MS I *think* that with the t-case in neutral the front and rear output shafts are locked together. try it in hi range.


Yep, that's what I meant!

[Daurie]

Or your parking brake could be dragging / have issues. What was the outcome of your previous thread concerning the parking brake?

[thixon]

Based on what you say, its not the ebrake. if it was the ebrake dragging, you'd have met resistance from it when you jacked both wheels off the ground, as well as when you'd had only one off.

You mentioned rear brake adjustment was the project. Are you sure you didn't have something out of whack with the brakes on the rear wheel that wouldn't spin, that maybe you changed just before you jacked up the whole rear end?

Wat you describe with both off the ground (other side spinning in oposite direction) is exactly how an open diff should operate. What doesn't mesh is the one not turning when the other was on the ground. Also, if you had been in 4wd, with the fronts on the ground, then nothing should have turned (I think..yea, thats right).

The only other thing I can think of is you have some type of limited slip in there. When you had the whole rear jacked up, did the other wheel turn in the opposite direction right away, or was there some delay in movement of the other wheel?

[msggunny]

The only other thing I can think of is you have some type of limited slip in there. When you had the whole rear jacked up, did the other wheel turn in the opposite direction right away, or was there some delay in movement of the other wheel?

i cant remember right now, but i will check that out.

[Daurie]

Based on what you say, its not the ebrake. if it was the ebrake dragging, you'd have met resistance from it when you jacked both wheels off the ground, as well as when you'd had only one off.



Thixon are you sure about that? Msgunny said that when both rear wheels were lifted they spun freely but in opposite directions from one another, exactly as an open diff should. It seems to me that whats NOT turning is the drive shaft. That would lead me to first check the ebrake and then onto the transfer case and forward.

I'm also not sure about this but with the transfer case in neutral the input shaft and both front and rear output should turn independently. (next time mines on the lift I will most certianly check this out)

So Msgunny, with the transfer case in N (as well as the tranny)
I feel certain the one wheel should have turned along with the drive shaft, with only one wheel lifted.

With conflicting opinions coming your way, you could disconnect the rear drive shaft and try turning the parking brake drum. With everything in N it should rotate freely. While the shaft is off lift one rear wheel and check out that too. This should give you the answers you're looking for. It will also tell us if the front and rear drive flanges are locked together when the t case is in N like daveb suggested.

[Apis Mellifera]

This may be of some help:
http://ollr.10.forumer.com/viewtopic.php?t=3778

I'd jack up the F and R tires on one side and see if spinning the rear spins the front. It seems plausible that with the TC in N, the front and rear difs my be engaged with each other.

[I Leak Oil]

Jack up rear wheel.
Put X-fer case in 2wd.
Put transmission in N.
Hand brake off.

You should be able to move the wheel. (Go ahead, give it a good shove, this isn't a pillow fight.....)
If you can't, disconnect the DS at the diff and try moving the wheel again. (it's only 4 bolts)
If it doesn't move, it's on the diff. end.
If it does, you've got something else going on up stream.

Jason T.

[Daurie]

I've just confirmed that the front and rear drive flanges are only locked when the levers are in the 4wd position. Yellow down or red back. Red hi -low lever in neutral disconnects everything from one another.

[thixon]

Thixon are you sure about that?
.

Daurie, Actually no, I'm not sure about it. After thinking about it further, you're right. with an open diff, both wheels jacked up, the wheel on the other side would turn (movement transferred through the spider gears). If the shaft was locked, then he would have met resistance with only one wheel up, hence the inability to turn the one wheel. You're reasoning is sound, and I agree. I was just a bit puzzled by the fact that he was certain everything was in neutral, and that the truck ran and drove fine.

[Daurie]

I'm puzzled too.. if it's not the ebrake I wonder what the chances are of a binding pinion bearing? Hows the gear oil level in the rear diff? Condition?

[SafeAirOne]

I'm puzzled too.. if it's not the ebrake I wonder what the chances are of a binding pinion bearing? Hows the gear oil level in the rear diff? Condition?

As discussed earlier, a binding pinion bearing is easy to diagnose--Disconnect rear propshaft, jack up both rear tires (or even just one), and start spinning the prop flange on the rear diff and check for binding/ too much resistance.

If you find any problem, ground the truck immediately and investigate the cause. ---I can confirm that a pinion bearing failure has the ability bring the whole truck to an immediate and difinitive stop (as in your whole axle unexpectedly locks up). I was fortunate and sensed something odd...an intermittent hesitation...when I was Rovering down the highway. I pulled off the exit and almost all the way into a 7-11 parking lot to investigate when the front diff locked up. If I didn't have shoulder belts, I'd probably have an imprint of the steering wheel on my forehead right now.