Chrysler 8.25 Gear Install

Old 08-20-2008, 09:29 AM
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Join Date: Aug 2008
Location: Denver
Posts: 82
Year: 1988
Model: Cherokee
Engine: 4.0ltr
Default Chrysler 8.25 Gear Install

Here's the 8.25 out of a 2000 XJ
Here you can see the center pin and retaining bolt that needs to be removed.This diff. already has a loc-rite locker installed so the spider gears are no longer in place.

To remove the loc-rite center gears, first the springs need to be popped out

Then the center gears of the locker can be removed, the axles are pushed in slightly and the c-clips fall out, then the axles slide out of the housing. i've also removed one of the carrier bearing caps, you can see the side adjuster nut and the carrier bearing race under the cap.

After the other cap is removed, I use my homemade tool to turn the adjuster nut slightly, and release the side load on those bearings so the carrier will easily slide out.

That tool is a Toyota tortion bar, with two flat steel pieces welded on one end, It is made to fit tightly inside the side nut.

This end has an old broken 1/2" socket adapter welded to it.

After the carrier is removed, I spin off the pinion nut with a 1 1/4" socket, then I knock out the pinion gear and i hold one hammer against the gear, and strike it with another hammer, so that I don't damage the end of the pinion gear.

Then I knock out the pinion seal, and now I can knock out both pinion bearing races. There is a slot on the top and bottom of the housing that allows the punch more contact with the race, I work the race out evenly by moving back and forth from top to bottom and moving the race a little at a time.

The new races can now be installed and I cheated and used a pic from another install to show the driver I use. A brass punch can also be used to drive in races.

Now I move on and remove the old inner pinion bearing from the pinion gear

I do that only so that I can access the shims that are under the bearing and measure them

There are actually two shims stuck together under that bearing and they together measure .020". As long as these shims are not damaged, i can re-use them.

Here i've used an old bearing race that fits over the pinion gear loosely, but only contacts the inner race of the new bearing. I tend to keep alot of old bearings and races around as they make good press fittings.

Here I'm pressing the new bearing onto the new pinion gear, with the original shims installed.

Last edited by Kyle; 08-20-2008 at 10:31 PM.
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Old 08-20-2008, 09:34 AM
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Join Date: Aug 2008
Location: Denver
Posts: 82
Year: 1988
Model: Cherokee
Engine: 4.0ltr

Now I can move onto putting new bearings on the carrier

This blurry picture show the carrier sticks out of the center of the bearing some. I did not find in my collection, anything to use as a fitting that would fit around that carrier, and still only contact the inner race of that bearing.

So i will use one of the old bearings as a press fitting, but i have to make some modifications so that when I press on the new bearing, the old race does not get stuck onto the carrier that sticks up above the bearing.

First I cut the cage off of one of the old bearings, then I cut a slot in it so it would not get stuck on the carrier. I'll use it as a press fitting for the new carrier bearings.

Before I press the carrier bearings on, there is an issue with the ring gear to deal with. The picture below shows how much taller the 4.56 ring gear is than the 4.10 gear.

As you can see here, the center pin won't go in unless I clearance either the gear or the pin. PORC sold these gears and they recommend grinding off part of the ring gear tooth, it's an area that probably won't contact the pinion, and they still warranty the ring gear. I want the carrier empty so that what ever metal shavings are created, can easily be washed off.

Sorry for the blurry photo, I had to take off a bigger protion of that tooth than i expected.

Once that's done I wash and blow off the carrier and then press on the bearings

Now since i used the old ring gear bolts to pull the ring gear onto the carrier (new bolts should just be used once so I use the old bolts for that) I will install new bolts with some loc-tite on the threads and torque them to spec in a star pattern. They are left hand thread bolts.

Now I can start assembly. I lube all the bearings with some oil and install the pinion gear assy, leaving out the crush sleeve, I carefully tighten the nut until I get to 12-15 inch pounds of rotational force.

Then I can install the carrier, taking care with the side adjuster nuts and caps to insure the threads are aligned and the nuts turn freely as I tighten down the caps.

Then I turn those nuts and adjust the carrier postition, my final goal is to end up with .006" to .010" backlash, and to have those nuts torqued to about 90 lbs, to insure good carrier bearing preload.

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

and here the final reading is .0075" backlash

Now I can run the pattern to insure the pinion gear depth is good. If the pattern is off, I will need to remove the inner pinion bearing and change the shim pack, my Yukon bearing puller makes it possible to do that without damaging the bearing. Otherwise a setup inner pinion bearing should be used until the pattern and shims are correct, then the new bearing can be pressed on.

Drive side

Coast side

My pattern was good, so now I take the carrier and the pinion gear back out, put the crush sleeve on, reinstall the pinion and yoke and tighten the pinion nut until I get the same rotational force as before. It takes alot of force to crush that sleeve so a LONG breaker bar and pipe wrench are used to hold the yoke. Care must be taken so that I don't go too far and ruin the crush sleeve.

Then I need to take the yoke back off and install the pinion seal. To make sure I have the nut in the same position after I install the seal, I first marked it with a chisel line on it and the pinion gear, then I can remove the yoke and install the seal, and then re-install the yoke and the nut to the same position.

Now I will reinstall the loc-rite locker and now is the time to re-install the 8 springs that are around the center pin.

They are positined in the inner side gears of the locker, I fill the holes with bearing grease so they won't fall out and then slide the springs in, the center pin can now be installed and it needs to be rotated as it goes by those springs so that they will retract into position.

Now I just have to install the cover and this diff. is done.
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