Pmoon

Ok, so I knew my center support bearing on my drive shaft was about to blow up when I left the house tonight but I drove the 40 miles to my son's baseball game and sure enough it self destructed as I drove into the parking lot of the ball field. I ended up removing the drive shaft and driving it back home in 4 high (front wheel drive!)
I already have a driveshaft ordered and should be here in a couple of days. My question is, am I doing any harm by driving it this way?

Mod (Ret.)

I've done this as well on an older Jeep CJ5, except I did not have any tools to remove the rear driveshaft; I found a coat hanger that I used to allow the rear drive shaft to sit on while I limped home a few miles (the rear driveshaft's front U-joint broke). I was lucky the coat hanger held up long enough with it suspending a spinning driveshaft from the rear wheel differential still connected to the driveshaft!

Since you removed the driveshaft, that part (rear) is a no brainer, but I've heard that the front differential is not intended to be operated on "dry" surfaces, as the front differential is not set up to compensate for right and left turn axle spin on dry surfaces. The rear differential allows for the inner or outer axles to spin at different speeds when a turn is made (right turn, right axle needs to spin slower than outer/left axle), but I don't think the front 4x4 differential is set up to do this. This is an excerpt from a 2007 owners manual:

Towing

Do not exceed a distance of 50 miles (80 km).

Do not exceed 35 mph (56 km/h) vehicle speed.

The vehicle must be towed in the forward position to ensure no

damage is done to the internal transfer case components.

If a distance of 50 miles (80 km) or a speed of 35 mph (56 km/h) must

be exceeded, you must disconnect the front (4x4 only) and rear

driveshafts.




Improper removal/installation of the driveshaft can cause

transmission fluid or transfer case fluid loss, damage to the

driveshaft and internal transmission and transfer case

components.


Vehicles equipped with Control Trac four-wheel drive system:


Vehicles equipped with the Control Trac four-wheel drive system cannot

be towed with any wheels on the ground. See your authorized dealer if

you must flat-tow a vehicle equipped with the Control Trac four-wheel

drive system.

2H (2WD High)

– Power to the rear wheels only; used for street and

highway driving. Provides optimal smoothness and fuel economy at high

speeds.


4H (4WD High)

- Used for extra traction such as in snow or icy roads

or in off-road situations. Not intended for use on dry pavement.

N (Neutral)

– No power to either front or rear wheels.

4L (4WD Low)


– Uses extra gearing to provide maximum power to all

four wheels at reduced speeds. Intended only for off-road applications

such as deep sand, steep grades or pulling heavy objects. 4L (4WD Low)

will not engage while the vehicle is moving above 3 mph (5 km/h); this is

bwFX42006

So basically the rear differential is an LSD (B6 Axle) and the front is an open differential because it does not allow power transfer via pre-loaded internal spring?

RajunKajun59

Bucko, I don't beleive it is the front Diff that can't compensate for the differences in rotational velocity of the two tires but rather the Transfer case. The Front should have an open or LSD type differential similar to the rear, the Transfer case locks the two shafts together, turning on dry pavement generates 4 different wheel speeds, the front and rear diffs can compensate for the differences on each axle but the Transfer case cannot compensate for the two drive shafts, being at different speeds. AWD systems have a central diff that allows them to work.

So driving in 4hi with just the front shaft as an output should be alright for a short term.

lewissa81

^^^ this. The front diff is open. Personally, I wouldn't rely on the front axle to handle the full power and weight of the truck for long, but should be fine as a temporary "get you home" fix.

Mod (Ret.)

Thanks for setting me straight folks, and hopefully the OP on this one.

Pmoon

Thanks guys, just got the driveshaft a day early so should be installed this afternoon. Appreciate the responses.

Pmoon

When I was under the truck installing the new driveshaft i noticed the whole bottom of the truck was sprayed with transfer case oil , so I went to my local oil change shop and got an oil change and had them check the T C. Turns out it was about 1/2 way down so no major damage but I wouldnt want to go several hundred miles that way.

Mod (Ret.)

Good catch...I guess it needed a change anyhow!