Jason From The Island of Kauai Gets Nitro 4.88 Gears
(61 BIG pics loading)
MAY 10 2014

Jasons 1993 Toyota pickup has 210,000 miles and it looks like it ran low recently on gear oil and the 488 gears are
now toast. After some email exchanges, a package from JT's arrives.


Nitro 488 29 spline ring/pinion...29 spline multi-drilled flange....master install kit.


Because of where Jason is and the cost of sending a 65 pound 3rd to me, it was decided to use a core that I happen
to have. So, I have a solid collar, a basic core, and a basic 2 pinion differential case for this project.

The large rear pinion race is tough to press in sometimes. The trick is to get it started straight
so I use a "bubble"......

...and make sure the bubble placement is the same before I apply pressure from the press.

Save your old races. They come in handy for pushing bearings in place.

The race goes down a long way. If a chisel was being used, it's very easy to think you have the race bottomed out
when it's not.

The small front race is more straight forward....just use some old bearing parts and a hammer to tap tap
it fully in place.

Front(outer)race is verified in 100%.

.080" is the 1st choice for this Nitro gear set.

Press the big bearing on with the Harbor Freight press.

Installing the pinion assembly is a straight forward operation with the right tools.

For this paint check, 18 in/lb is aok.

Now to prep the case end.

The carrier bearings did not press on as tight as I wanted so #638 retaining compound is employed on both sides.

The course file found no burrs or high spots on either mating surface.

The ring was a tight fit but I was able to get it to seat down with the lead filled plastic hammer.

Red loctite on all 10 ring gear bolts.

75 ft/lbs.

I use extreme care when aligning the bearing caps...it's too easy to damage the threads.

Dial in some sort of bearing pre-load while guiding the backlash in the .008" zone.

DRIVE----very near centered and appears to be "exact depth" but I think we can go for that "slight deep" look
with a little thicker shim.



Now to push the pinion assembly out.

Remove the bearing...

...and substitute this .083" shim in place of the 080.

Press the bearing on.

Use the electric impact to gently nudge the pre-load to about 10~20 in/lb.

Another paint check...hmmm, didn't move hardly at all in terms of a deeper look.

COAST---not much change.

I didn't make a big enough change by adding only .003"....this pinion shim is .0885" and, doing
the math, is an additional .0055" deeper.

Now this is much better. Has the deep look...slight favoring of the toe.

COAST---depth looks slightly deep and favors the heel ever so lightly.

Not a very good pic of the pinion...again.

Now to remove the pinion again but this time to install the solid collar. On the first try, I had 7 in/lb PPL
with a .026" shim on the solid collar.

This is the splashguard designed for the 27 spline pinions...and this is the fatter 29 spline pinion.

By using a "half round" type of metal file, enough material can be removed in about 4 minutes to
make a proper fit.

90311-41009 OEM pinion seal will be used on this 29 spline pinion.

This homemade tool will knock the seal down evenly and fully.

Gear oil is applied to all contact surfaces to prevent a dry start-up condition and to minimize the drag
of the rubber when I check the final PPL value.

I used to apply a red Loctite to the pinion threads....

....but, after much thought, decided it was not needed and possibly a hindrance. I have already deformed/destroyed
one 30 mm socket because I did not use an anti-seize compound on the threads
to help reduce the spiral thread resistance.

After tightening the 30mm nut as much as the electric impact would allow, the torque wrench was employed to tweak
the ppl to its final desired value of 10 inch/pounds start torque.

Once the nut is dinged it will never loosen up on its own.

75 ft/lbs on all 4 bearing cap bolts.

Backlash is dialed in and carrier bearing preload is nudged in place by tightening the adjuster wheels 1 notch
at a time.

I am measuring 14 in/lb start torque here. That's the force required to turn both the pinion and ring gear. That
means my pinion preload is still 10 in/lb and, doing the math, the carrier bearing preload is 4.

The lock tabs can now be secured....blue loctite(medium strength)....

....and 10 inch/pounds.

One final paint check and the drive side looks slight deep and a slight favoring of the toe. Excellent.

Coast looks pretty good, too. Deepish look and favoring the heel a little.


A snap shot of my assembly notes.


And, since this was going USPS to Hawaii which has a weight limit of 70 pounds max, a light but strong
rectangular box was created. Cut in half....

....and slide them together to make a super duty box.