I had a good day at the swap meet yesterday, I bought a 3 series True
Trac for a Dana 44 with reverse rotations 3.50 gears attached for $50.
I need to change the gears because I'm going install it in a standard
rotation front Dana 44. The front Dana 44 axle is from a '78 Cherokee
that I shortened to CJ specifications.
The True Trac went in very easily, mainly because I don't have the front
end installed yet. The hardest part was removing the open carrier. I
wrapped a cable around it and hung it from the ceiling to pre-load it
while I pried on one of the ring gear bolts. The FSM doesn't say
anything about hanging the whole axle from the ceiling by the carrier,
but I don't have a case spreader. Either way it worked out. The FSM does
say to pry on the case itself and the heads on the ring gear bolts to
remove the carrier.
After that I finally found my air impact wrench (and the trigger that
had broken off it and migrated to the back of a drawer) and situated the
Jeep so I could run it and use the on-board air. The ring gear bolts
came out very easily with the air impact.
With the ring gear off I dropped the True Trac into the housing and
snugged it down to see how the bearing pre-load would be with the
bearings and shims that came on the True Trac. It felt about right, so I
decided to see how the backlash and gear pattern were with those
bearings.
Next I swapped the standard cut ring gear over to the true trac and
pulled it up tight slowly and evenly with a ratchet. After it was good
and tight I applied lock tight to the bolts and snugged them up again. I
couldn't figure out a way to hold the carrier for the final tightening
(there are no holes in the sides of a True Trac to stick a pry bar
into), so I used the air impact.
After it was assembled I set the carrier in the housing and slowly
turned the bolts for the bearing caps to pull it down. I went in a criss
cross pattern, about 1/2 a turn at a time. Once it was down I checked
the backlash and gear pattern. Amazingly it was like I hadn't disturbed
anything. Both were unchanged from before. The only thing that was
different was slightly less bearing pre-load on the carrier, which is
good becuase I think I had too much before. It now feels like like it
should.
I saved the best for last, here's what I think I've learned from playing
with the axles. I could be wrong on any of it, but this is how it's
worked out for me:
The pinion depth shims seem to go with the pinion. The carrier shims
seems to go with the carrier. Meaning that if you are going to change a
gear set that is already set up into another housing try the shims from
the original setup, rather than the ones that went with the housing. So
far that's worked almost perfectly every time for me. If you are going
to change from an open carrier to a different carrier that's already set
up try the shims that are already on the carrier. If you are going to a
brand new carrier I'd try the shims from your old carrier first. When
changing carriers without changing gears I'd test fit the carrier,
bearings and shims without the ring gear first to see how the bearing
pre-load feels.
Changing bearings and shims
If this is what scares you about doing gears don't be scared. The
carrier bearings are the hardest to remove, and they aren't that hard.
For special tools you will need a decent sized bearing sepparator (about
$15 from a discount tool place), a 2 jaw puller (another $12 or $15),
and some kind of spacer to put in the hole in the case for the puller to
push on. Most people probably have some kind of spacer laying around
that will work, or you can buy a wheel bearing race driver set and use
one of the driver pucks for the spacer ($20 to $40). You put the bearing
sepparator on the carrier bearing, put the puller on that and tighten it
down until the bearing comes off. You don't need a hydraulic press, the
bearing will come off with a ratchet or at the worst a breaker bar
turning the nut on the puller. It's hard to hold the puller still, so I
usually clamp one jaw in a vice.
Pinion bearing races and shims are driven out as easily as wheel bearing
races in a CJ front end. There are 2 sets of shims here, one behind the
inner pinion bearing race and one on the epinion itself. The shims on
the pinion are for bearing pre-load. The shims behind the race are for
pinion depth. All you need to get the races out is a brass punch ($10)
and a hammer.
