True Trac install

by John Nutter

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 to 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 preload 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 preload 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 uptight 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 chris 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 preload on the carrier, which is good because I think I had too much before. It now feels 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 seem 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 preload 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 separator (about $15 from a discount tool place), a two-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 separator 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 two sets of shims here, one behind the inner pinion bearing race and one on the opinion itself. The shims on the pinion are for bearing preload. 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.