Rear gearing question? Axle won't spin

[AlaskanJack]

I finally jacked up the rear to spin the wheel and count the driveshaft turns.

Problem is the rear wheels turn in different directions and the driveshaft doesn't move. What is going on?

I was told to spin the wheel and count the driveshaft revolutions through one wheel turn.

DOHHHHH!!! just read another thread "put it in nuetral" dummy

 

[Crankcase]

If the wheels are turning in different directions, it is an open diff.....

 

[AlaskanJack]

Really I could have sworn that the door sticker was for a LS diff.......awww crud now I have to run out in the snow and check it again

 

[AlaskanJack]

Don't try and start crap, you almost got me killed!!! ok Crankcase hehehe

I just ran outside to check my door panel and it read D4 which is LS. I ended up almost running into a big damn MOOSE that was laying down next to my rig. She popped up and I saw her horse sized young offspring next to her. I slipped on ice fell on my arse then jumped into my truck. I hit my light bar lights which lit up the neighborhood and turned on my stereo loud. I guess she didn't like Red Hot Chili Peppers

Ok so now that we know the wheels spin in opposite directions(in park), what does this tell me since it is a LS diff????

 

[Crankcase]

Just because the door sticker says LS, doesn't mean it couldn't have been changed.....or worse, the LS is completley toast....

 

[AlaskanJack]

Well I have to admit I don't know crud about diffs and axles. I've been trying to learn and research info. Why would someone remove a LS rearend and replace it with an open carrier diff? If the rearend was jacked up and vehicle was in nuetral I could spin both wheels together just fine, I had to do this because when I spun only one wheel my driveshaft rotation was just over 2 revolutions. So I thought hmmm I spun both wheels at the same time and came up with a little over 4. What's with that?


Edit: the diff has been worked on since the label is gone and the ABS sensor on the axle has had the wires cut to it. Maybe the axle is off a newer explorer or different vehicle. ???

 

[Crankcase]

Is this the 91 that we are talking about right?

 

[AlaskanJack]

Originally posted by Crankcase
Is this the 91 that we are talking about right?

Yes it is, I added a pic of the rearend I had. I may have to just pop the diff cover and see. I hate to because it has been sealed up nice and tight. The diff cover has been sealed and all bolts have been sealed up no worries about getting water in that axle.

 

[Crankcase]

Why is finding out the ratio so important to you?

 

[Crankcase]

IMO, maybe the previous owner replaced the axle with a 93-94 axle, and put in open gears....Why? I don't know. Maybe the axle was a factory open, and he kept it that way...

 

[AlaskanJack]

Well I guess I'm just ****. I used my speed and rpm's in drive and the calcs checked by Alec came up to 5.13 gears. Seemed high and I wanted to know for sure. Now after spinning tires I came up with approx. 4.10 It's just me wanting to figure out what all has been done to the vehicle. I know the steering column was replaced with a 93-94 column with the cruise buttons even though the vehicle never had cruise control on it. I had been figuring that the reason why the ABS sensor was disconnected was because the ring was not re-installed when the gears were changed. Maybe it was because the axle was out of a vehicle with 4 wheel ABS.

 

[Crankcase]

Originally posted by AlaskanJack
Maybe it was because the axle was out of a vehicle with 4 wheel ABS.

That is what I was thinking after you mentioned that...

 

[AlaskanJack]

Hmmmm ...... well I just can't see going from a LS to open diff. Especially with the kind of mods made to the truck it seems weird that they would do this. Wait the LS transfers power to wheels with traction. The open diff does not, so does that mean it acts like a locked diff? I may be seeing the why if it does??

 

[SteveVB]

It looks to me as if you have either a really worn out Trac Lock, or an open differential.

The LS is normally "locked" and will slip when the difference between the left and right shafts crosses the prelaod of the spring/clutch pack. It doesnt really transfer the power to the wheel with traction, but it acts like that since they are connected together -UNTIL the traction at the wheel (l orR) overcomes the clutch/spring assembly. With your tests you may be applying enough torque to overcome an old or weak clutch set.
Open differentials wheels will spin in opposite directions unloaded, and L/S and Lockers should spin the same direction when you turn the wheels or hubs.

An open diff if you turn the wheel will only rotate at half the gear ratio, but if you turn the DS you should be able to get the ratio. So from what you have said it would seem to be either a 3.73, or a 4.10.

As much as you dont want to pull the cover, I would, since IF you do have a LS it would seem to be in need of a new spring, or clutches. And since you sem to have some question as to the heritage of the axle it will give you piece of mind. The Gear ratio will be stamped o the ring gear so it will be easy to tell, and the large S spring in the diff will tell you quickly whether you have a LS.

 

[AlaskanJack]

So do you reccomend pumping out the fluid or just cracking the seal and letting it drain? Just curious is all I have a pump so I can do either.

So does the open differential act like a locker in that both wheels spin no matter what the traction is? I was thinking that whoever built this truck up may have decided for the open diff if it acts like a poor man's locker.

 

[SteveVB]

I wouldnt mess with the pump, pulling the cover is much easier and much much quicker.

No the open diff will not act like a poor mans locker. When the traction differences between the two wheels differ the one with the most traction will STOP spinning, and the one with the least available traction will recieve the power(spin).
The only "poor mans locker" I know of is the brake, either the pedal or the parking. The idea being if you apply the brake a bit you equalize each of the wheels so power goes to both- I can say it works well for short periods, but is tough on trannys, and brakes.
I was once stuck in some sand at the entrance to the beach in Corolla NC, and there were about 4 trucks that were stuck in the same place- one lane was going in and out and everyone was taking turns going through. My turn was up and I was waved on by someone trying to come in, I started up and was in the worst section of blow sand, a truck strapping another out cuts right in front of me and I lost momentum and sank into the sand with one front and one rear wheel spinning. Everyone expected me to stay right where I was - the cherokee stuck up to its doors next to me was congratulating my father through the window on joining them. I put my foot on the brake, and he other on the gas and lifted myself right out of the hole- to the cheers of everyone waiting to get on or off the beach since I was in the only path left. My best use ever of the "poor mans locker".

Pull the cover have a look, see what is really in there.

Good Luck.

 

[Forder]

My truck does the same. I had it up on a lift last week and I turned the right rear wheel to see what the other wheel would do. I've checked my axel code before and it said I have a 3.73 LS Diff. But when I turned the wheel, the wheel on the other side turned in the opposite direction, which at the time I thought was normal for a LS diff to do. But now you all are telling me that is what an open diff does or that my clutches in there are terribly worn. So my Q is: is there a kit I can buy to replace these clutches and restore my LS? Or what is the best (cheapest) way to get my LS back?

 

[MrShorty]

Forder: yes you just buy a trac-lock rebuild kit. it will have the clutches, steel plates, new pinion shaft lock bolt, assortment of shims, and a bottle of friction modifier. I started a thread last summer that discusses replacing the clutches and has a couple of links to write-ups on the procedure.