One rear wheel spinning on XJ

Hey Bob, Nothing wrong with your differential... use 2nd gear and feather the clutch or use 1st gear with no throttle for spin free take offs. You could also toss a couple sandbags in the back for some weight... or better yet, 4 12" subs in a ported enclosure.

Putting it in 4wd engages the transfer case which divides power to the front and rear axle. While increasing traction, it also decreases power to any given wheel lessening the tendency to spin. Wheel spin may be less apparent in reverse for a couple reasons. Lower gear ratio and you're less likely to be applying as much throttle as you would be going forward. Your rear springs can play a huge roll in traction as well... less evident in slippery conditions however.

-Brian

Welcome to Jeeps!

You are describing how an open differential works on any vehicle.

If you are on ice, the wheel with the least traction can break away first and spin. Using 2nd gear loads the wheel up slower so it is less likely to spin.

This is why lots of folks put limited slips or lockers into their differentials.

Both wheels get equal torque all the time. If one is spinning on ice, that takes almost no torque to do, so the one sitting on dry land is seeing almost no torque and it just sits there.

Here is a trick for you that works really well with practice.

Get one wheel on the ice and the other on dry land and try to go forward in 2 wheel drive for learning purposes. When the one wheel starts spinning away, hit the brake pedal in a hard pulse and give it gas at the same time. You might have to hit it a few times with different pressures.

With practice, this will put a load on the spinning wheel. If you get it right, this load will equal the load needed to break the wheel on dry road free or equal that load.

Then you have 2 rooster tails and away you go.

It also can work in 4x4 to get all 4 spinning, but it is difficult to do with the front disk brakes. The rear drum brakes transfer the load better.

The owners manual for my 88 Cherokee says you can use the emergency brake to load up the spinning tire in the same way to get both spinning, but I have never had any success with that method.

Mike

Bob wrote:

Command-Trac,

I must be missing something here.. you bought a 4x4 so that you could use

Thanks for the info folks, I guess I was expecting a little more traction than I'm getting; I'll try the braking trick, sounds excellent! I just moved to the snow, and I've been driving my rear-wheel drive car around, and I expected the Jeep to have at least that much traction in 2wd...but I suppose the rear end is pretty light. What worried me about it is that before I bought it I didn't know about the difference between Command and Select Trac - I thought all Jeep 4x4's had a differential between the front and rear axels. My concern has been when you are driving on a snowy section you'd have it in 4H, but then if you hit a bare patch you have to shift it to 2H so as not to wind up the transfer case. I'm sure I'll just get used to it. It's old but in excellent condition, I'm going to order a 2-3" lift kit and put maybe 31" tires on, I can't wait to use it up in the Rockies! Thanks again,

Bob

Command-Trac,

Good point about reverse pulling it down, I had forgot about that. I just always think of reverse as a higher ratio than 1st, which was why it didn't make sense to me. I'd love to leave it in 4wd on the roads here, but there are so many bare patches mixed with ice here, after reading posts about the Command-Trac I'm worried I'll blow the transfer case out on the first one I hit. I know you can shift on the fly but is it bad to keep going back and forth at city speeds?

No issues using 4x4 just like any other shift, I do it all the time around here.

Going straight also isn't hard on Command Trac, it's turning corners on dry that causes problems so hitting the dry and waiting or needing a minute before shifting back to 2 wheel drive isn't an issue.

You also might want to use 2 wheel drive at intersections if you plan on turning. If your tires are too wide, they will get up on top of the snow and float and it will want to go straight.

I made a mistake and put too wide of tire on our Cherokee. I went up to a wide tread BFG AT P235's and they handle very poorly compared to the skinny tread Hercules Terra trac P225's we had on there before.

All brands are not equal for tread width. The BFG's are a 'lot' wider than some other brands of the same size.

Same deal with our two Jeeps. My tall skinny mud tires can run circles around my wide AT tires in the snow.

Mike

Bob wrote:

Hi Bob,

Be very careful with the braking trick or this might happen to you:

Don't worry about frequent 2HI/4HI shifts at any legal speed. Remember that windup is not an issue on straight sections. If the bare patches are in the minority, the drive train can unwind when you're back on the snow.

Steve

Bob wrote:

I don't get your point.

Those photos are not clear enough to show anything except a Jeep and snow.

Mike

Steve wrote:

Selectrac and Hercules Terra Trac Touring Ltds here.. they may not look beefy and are not rock crawler material by any stretch of the imagination, but they sure as hell propel the GC through any kind of snow.. have been in fulltime 4x4 since October..

Well, the pinion angle is a little, um, odd...

/Peter

Good guess, but not quite.

I managed to spin the diff on the tubes. The pinion yoke strap bolts sheared off and the pinion ended up nearly vertical. Also twisted the splines on the t-case output slip shaft.

I was on the brakes and gas way too hard and one of my tires was firmly immobilized on a stump. Obviously, applying the correct technique on a slippery street will work great, but under certain circumstances you can cause major strain if you don't know exactly what you're doing.

I spun the diff back in place (actually improved my pinion angle a bit) and welded it. Its been holding up fine while I work on my D44 swap.

Steve

L.W.(ßill) Hughes III wrote:

Interesting about the tires, the BFG 235's were something I was looking at. From what I figured out the tires with the 33x9.5 numbers are "high floatation" tires which seem to be preferable to the LT235 etc series. If the rims have 225 stock, how can you tell what size in the "33x9.5" size system they will accommodate? Can you just take the width of your rim (which I actually don't know...) and then is there a max over that that the 9.5 part can be?

Bob