D44a Gear install

Old 10-17-2008, 09:33 AM
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Join Date: Aug 2008
Location: Denver
Posts: 82
Year: 1988
Model: Cherokee
Engine: 4.0ltr
Default D44a Gear install

Kamil has a 2003 Grand Cherokee and the Aluminum housing D44a and his D30 front are getting new gears.

Pulled the rear first

After getting the diff. on my cart, I removed the 4 axle shaft bolts, and I'm using the rotor as a slide hammer to pop out the bearing and the seal

Then I did the same on the other side, looks like the left axle seal is just starting to leak a little, the backing plate has a little bit of oil on it.

The other side is nice and dry

Next I removed the carrier cap bolts, and then I set up my case spreader and dial indicator to .016", and I spread the case. I was then able to remove the carrier and it took only a little bit of prying force to pop it out of there. That's good, it means that the housing was set up with the proper amount of carrier bearing preload, and I should be able to re-use the shims that are installed in it now.

Those shims setting on the cart, are installed outside of the carrier bearings and fit between the race and the housing

I always keep track of shims by hanging them up, "T' is for the tooth side of the carrier, "B" is for the bolt side

The pinion gear can come out next, it takes a little force to get it out of the bearing, I hold one hammer against it and hit that hammer with another, that way I won't damage the threads on the shaft. Kamil might want to sell these to someone.

Here is that pinion shaft and all the parts that go on the assembly

Now I can punch out the races that are pressed in the housing, I make sure and move the punch around and work out the race evenly so it doesn't bind.

Then I can clean up the case and install the new races

The pinion depth is set by shim(s) installed under the inner pinion bearing, I need to know what thickness is installed now, So here I'm using my puller to get that bearing off of the old pinion shaft

My puller works real nice and never damages a bearing, and usually doesn't damage the shims, I will just reuse this shim on the new pinion shaft.

Then I will go ahead and pull both carrier bearings so I can replace them

Then I cleaned up the carrier and removed the spider gears so the Aussie locker can be installed later

Now I can install the new ring gear on the carrier, I used loctite on the bolts and torque them to spec. in a star pattern

Now I can press on the new carrier bearings, by the way a good press fitting can be made from the old bearing.

First I cut off the outer cage, and then cut a slot thru the race

That fitting is needed and has to be just the right size, if I were to use a flat plate, it would bend the cage of the bearing, that's because the cage sets a little higher than the inner bearing race, also the inner bearing race has to drop below the carrier lip a little.
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Old 10-17-2008, 09:36 AM
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Join Date: Aug 2008
Location: Denver
Posts: 82
Year: 1988
Model: Cherokee
Engine: 4.0ltr

Now I can get the pinion shaft ready to install, here's the assembly, I will leave out the crush sleeve for now. I won't install it until I know the pinion depth is correct.

The first thing I will do is grind off the locking portion of the old pinion nut, sometimes that locking area will damage the threads on the pinion. I will use the old nut until I have everything set and the pinion seal installed, then the last thing I will do, is install the new nut.

Now I can press on the new pinion bearing with the old shim under it.

Then I can install the pinion assy back in the case and I tighten the nut until I have the correct pinion bearing preload (you'll see that measured later) The carrier also goes back in the case with the original shims, I then release the case spreader and run the pattern.

This pattern is showing me that the pinion is a little to deep in the case.

Coast side

Drive side

So I will need to pull the carrier and the pinion shaft back out of the housing. I will use my puller and remove the inner pinion bearing. And I will change shims so that they are about .003" thinner.

Here the shim that was under that inner pinion bearing is .035" thick.

And the new shim pack I will install is .032" thick

Then I reinstalled everything and ran the pattern again

Good on the drive side

Good on the coast side

Now that I know the pinion depth is good, the carrier and pinion have to come out again, and I will now put the crush sleeve on the pinion gear, I will also go ahead and install the pinion seal. Then I installed the new pinion nut and tightened it down.

To get that crush sleeve to crush, takes alot of torque (about 300lbs), I use a pipe wrench on the yoke and a long pipe on the end of the wrench, lock that aginst my cart, then I have a large 3/4 breaker bar that I put a long pipe on. Once the crush sleeve begins to crush, it is then a little easier to turn.

I have to be very careful, when I get to where there's no in and out play felt on the pinion, I can only turn the nut a little bit at a time and keep checking the turning resistance of the pinion with an inch pound torque wrench. If I overtighten that nut, the crush sleeve is ruined and I'll have to get another one.

The spec. for the turning resistance or pinion bearing preload is 14 - 19 inch lbs, with no seal installed and with no carrier in the case.

I decided a while ago that I was going to always install the seal and add a couple lbs to the pinion bearing preload spec. Otherwise I have to set it, take the yoke back off, install the seal, and then try to get that nut to exactly the same position as it was. I feel that makes it difficult to not be a little looser or tighter then before the seal was installed

Here is my inch pound torque wrench, the blue needle shows the highest number I had while rotating the yoke, about 17" lbs and that's good.

I could tell last time I had the carrier in that the backlash was a little too tight, but I needed to get the pinion depth set correctly first, and once that was correct, I could set the backlash.

So I changed the original shims that were installed on the outside of the carrier bearing races, I made the tooth side .003" thicker, and the bolt side .003" thinner.

I reinstalled the carrier with that shim change, then installed the carrier bearing caps with the bolts just a little tighter than hand tight, then I released the tension on the case spreader and torqued the cap bolts to spec.

Here I set up the dial indicator and zero'd it out.

Then I rocked the ring gear the opposite direction against the pinion gear and measured that. Backlash was between .007" and .008 " and that's good

Now I will install the Aussie locker and the axle shafts and this D44A is ready for the trails!!
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