t-case lower question

One of the problems is not so much the length of the driveline, but the angles that it connects to the tcase and diff. If you drop the tcase, you will straighten out one of the angles.

Raise the Tcase and add a CV driveshaft -- or even better, combine it with a fixed yoke and get an even longer drive shaft.

Just finished mine on Tuesday evening!

That is to get the angles on the driveshaft u-joints correct.

You also can get 1" taller engine mounts to do the same job. The engine and tranny pivot on the tranny mount dropping the end of the t-case down so the angle comes back.

The other option is to get a CV axle and tilt the rear end up with shims making it straight with the driveshaft.

Mike

Fletcher wrote:

getting to details now. This is a 83 CJ-7 with the T5 and D300

Ok this brings me to a second question. I recently picked up a dana 44 from a scout that I need to gear and lock up before I install. The spring perches are not quite right so they need to be moved anyways. What if I weld the perches so that the axle is slightly rotated in an attempt to help straighten the driveline angles. Any issues with this?

Hi Bill,

What is your definition of "constant velocity u-joints"? I always thought they consisted of a total of three u-joints per shaft, two of which are right close together and encapsulated. My Civilian Jeep has simple drive shafts - two u-joints per shaft, one on each end.

-- JimG

The scout axle will be much wider than your stock unit. If you use one on the front (to match the back), the perches would have to be out-boarded from the frame, or the axle would have to be cut down (then it would be more narrow than the rear). But yes, you would rotate it so that the pinion is more direct to the t-case, very common in SOA's.

-- JimG

Don't get too crazy shimming. You can go up to like 7 degrees. I don't know the exact angle but this information should be available on-line somewhere. It would probably also depend on which type of axle it is (Dana 30, Dana 44, AMC 20) The danger is tilting to the point the oil will not travel properly to the front pinion bearing and seal causing them to fail prematurely.

Good point! What we do after an SOA is park down (for the rear) a steep hill and then top off.

The goal here is not to aim the yokes (diff yoke and tcase yoke) at each other, the goal is to make the pinion shaft and the tcase output shaft parallel to each other.

The measurements to take are to determine what the angoe is of the output shaft, then to set the diff so that the pinion shaft is parallel. If you raise or lower the tcase, then the angle of the output shaft will change, and this can affect the position of the diff.

There is also a set distance that the two centerlines (the tcase output shaft centerline and the pinion shaft centerline) must be within. For example (and this is probably a bad example) the centerlines must be less than 1" apart. I don't know what the actual distance is, but I seem to recall that 0.25" or less sounds about right. (somebody please jump in here and help me out.)

The AMC20 that you already have has a low pinion, and if the new D44 is a high pinion, then you can raise the tcase as much as you want because the angles won't be an issue. You will still need to set the centerlines parallel, but the angles will not be so sharp where the driveshaft connects to the yokes.

This can be done ONLY if you have a CV joint driveshaft.

If you're running a standard drivehsaft, the 2 u-joints on the shaft must be in phase.

That means, if your flange at the t-case is pointing like this:

(viewed from driver's side)

o --> 2 degrees that way (at the top) | o