Sanity check on Dana 44: no shims, no preload, axle rotated backwards

[RainyLake]

I bought a fixer-upper high mileage 2001 TJ with a Dana 44 on the rear. It has a 4 inch lift and it seems the control arms are set up to rotate the axle so the driveshaft has a more or less straight shot at the t-case (so the pinion to driveshaft u-joint doesn't bind up). But this means the face of the pumpkin (as measured with the cover off) sits around 18 degrees off of vertical. Front Dana 30 looks to be similar. Is this going to cause any issues? Seems like in the front an extreme angle might mess up the steering since the knuckles will be rotated forwards - there's definitely some steering shaking at low speed, but I haven't diagnosed that yet. Also guessing that if this isn't the factory angle the oil fill level is probably way off too.

Also, I pulled out the Dana 44 carrier to check the condition of the bearings and discovered that there are no shims whastoever. Due to the angle of the pumpkin, once I unbolted the bearing caps, the carrier actually rolled right out of the pumpkin under it's own weight - no resistance at all. Am I right in assuming I should shim this up and reset the pattern? Bearings look OK, no chunks missing or anything, but feels a tiny bit rough to rotate. I was worried about them due to finding a lot of fine metal in the diff oil (was pretty old oil though) and then finding all sorts of gritty schmutz in the axle tube on one side. The backlash was 9 thou when I measured it but I didn't run a paint pattern on it.

 

[erokj]

The carrier should never roll out. You need to re setup the gears.

I would replace gears and bearings just to be safe.

 

[Jablinski]

" It has a 4 inch lift and it seems the control arms are set up to rotate the axle so the driveshaft has a more or less straight shot at the t-case (so the pinion to driveshaft u-joint doesn't bind up). But this means the face of the pumpkin (as measured with the cover off) sits around 18 degrees off of vertical. Front Dana 30 looks to be similar. Is this going to cause any issues? Seems like in the front an extreme angle might mess up the steering since the knuckles will be rotated forwards"

The rear pinion angle sounds like it is correct, if you have a double cardan driveshaft. The front shaft, being much longer, is more forgiving regarding pinion angle. Do you have adjustable control arms?
I've learned on these forums(and real world) that the pinion angle for the front is best determined by dialing out vibrations. Start high and lower the pinion (using your adjustable control arms) until you start getting vibes while driving. Then raise it in very small increments until the vibes go away. (Or start low... A skinned cat is just that).
This gives you your best available caster without vibrations. A tedious process, as you also have to ensure that your axle stays centered with the bump stops. Lots of write-ups on the subject.
I've never been concerned with oil levels being lower but some people seem to be.
Got any pics?

 

[RainyLake]

" It has a 4 inch lift and it seems the control arms are set up to rotate the axle so the driveshaft has a more or less straight shot at the t-case (so the pinion to driveshaft u-joint doesn't bind up). But this means the face of the pumpkin (as measured with the cover off) sits around 18 degrees off of vertical. Front Dana 30 looks to be similar. Is this going to cause any issues? Seems like in the front an extreme angle might mess up the steering since the knuckles will be rotated forwards"

The rear pinion angle sounds like it is correct, if you have a double cardan driveshaft. The front shaft, being much longer, is more forgiving regarding pinion angle. Do you have adjustable control arms?
I've learned on these forums(and real world) that the pinion angle for the front is best determined by dialing out vibrations. Start high and lower the pinion (using your adjustable control arms) until you start getting vibes while driving. Then raise it in very small increments until the vibes go away. (Or start low... A skinned cat is just that).
This gives you your best available caster without vibrations. A tedious process, as you also have to ensure that your axle stays centered with the bump stops. Lots of write-ups on the subject.
I've never been concerned with oil levels being lower but some people seem to be.
Got any pics?

OK, I started going down the rabbit hole of reading about pinion angles and I think I see what you're talking about. Basically tuning to reduce the u-joint wobble vibrations.

As far as the front, the longer driveshaft definitely reduces the angles, and when I measured the flats on the Dana 30, it's only 9 degrees off vertical, so it's probably not such a big deal as I thought.

On the rear, it looks like there are adjustable UCAs and fixed LCAs, although the threads might be too rusty to move if I need to. But the rear driveshaft isn't a double cardan, although I'm not sure if it's stock or not. I already dropped it so I don't have a picture showing the angle, although you can sort of infer from one of the other pics. So it might be that my only real rear axle problem is the shims & bearings.

 

[Jablinski]

Looks kinda high for a conventional DS. How are the u-joints?

 

[RainyLake]

You're right, it looks like it has the geometry of a double cardan without the double cardan. Now I'm rethinking what I did when I lifted my JK (3.5 inch AEV lift) - the advice I got was to install a double cardan front driveshaft but I did nothing about the pinion angle. Huh. Now I have even more questions.

The tcase end ujoint is fine - it's a sealed unit. The diff end ujoint is a bit rough and sticky - I'll replace it. It's a greasable unit though so I don't know if it failed due to lack of maintenance, or if it was overstressed b/c of the geometry. In any case, I'm leaning toward stressed, since the fact that it was replaced with a zerk fitted one tells me it already failed once before. Although I would have thought the t-case end joint would have failed instead, based on the angles.