When you install a 4" lift on a CJ, you then drop your t-case 1" to make everything work right? What is the point of that? Is that to prevent replacing the driveline as well? What would be the "right" way of doing this? I like the idea of tucking the T-case up as high as possible, even do a clocking kit, so a t-case drop is a move in the wring direction. Is the best thing to do not drop the t-case and get a longer driveline? will a clocking kit later down the road effect the optimal driveline length as well?
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.
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
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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?
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
80' CJ-7 258 CID
35" BFG MT on 15x10 Centerlines D44 Rear, Dana 30 Front. SOA
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
80' CJ-7 258 CID
35" BFG MT on 15x10 Centerlines D44 Rear, Dana 30 Front. SOA
4.56 Gears, LockRight F&R Dana 300 w/4:1 & Currie twin sticks Warn X8000i w/ dual batteries
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.
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.
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