Autopsy and 488 gear install
(34 low res pics loading)
OCT 8 2006

Charles, from Shreveport LA, recently purchased this very nice 85 Runner with dual Marlin cases, 35's, lockers, and 488's. Unfortunately, the rear end decided to go out so Charles decided to send it my way for an autopsy and new 488 Yukons. He was told by the previous owner that it had Genuine 488's and a Detroit Locker and I did verify that to be true.

New bearings and a solid collar will also be installed.

Using the lightest pressure from my finger tips, I was able to easily get the ring gear to click back and worth indicating that there was no carrier bearings pre-load (CBPL) to speak of. Charles tried to take a pattern check and that's why all the blue grease is on the ring in the pic.

The ring side carrier bearing came off by hand. I will make sure to use Loctite sleeve retainer compound upon re-assembly.

This does look like a Genuine gear which I have nothing good to say about... here's some pics to help identify this brand of gear...






The ring gear has chips all around the tow end.

The nut was still staked but the pinion had no pre-load at all and I could wiggle the flange and see the slop.

Upon removing the pinion, I was surprised to see it already had a solid collar. Looks like somebody made the effort to use the heavy duty collar but missed the whole boat by leaving all the bearings way too loose thus assuring self destruction. I believe the loose bearings happened first and that resulted in the teeth grenading.....not the teeth exploding first causing the bearings to all loosen up.

I filed the ring mounting surface and all seemed ok there but with all the bashing/crunching noises that must have happened when the teeth were exploding, I figured it would be a good idea to inspect the insides.


The teeth on the couplers all looked fine...

...same with the center driver....all looked great.

I layed everything out nicely and cleaned/inspected it. All was good.

The locker case itself may have deformed a little bit from busted teeth getting jammed between the ring and pinion. I did see about 2 thou run-out.

The Yukon 488 tapped on very lightly.

Previous Yukon gears like this one liked to see about .092" for a pinion shim... so that is what I chose for the first try.

And it appears to be at the right pinion depth.

Coast is nice but is favoring the heel some so I will try to open the backlash up and see if I can pull it closer to center.

I wanted to see what .012 backlash would pushed the drive side past center...

...but did not have any real effect on the coast.

I moved the BL to a reasonable .010" and that will do just fine. Here, I am verifying that the CBPL is at least 100 ft/lb. This does not strain the bearings like one might think. Tightening to 100 ft/lb effectively results in 10 inch/pounds of bearing drag on the carrier bearings.

Then I tighten it even more to fine tune the .010" backlash value.


After I remove my set-up flange, the pinion threads are cleaned and the splash-guard is loaded in place...

...a new seal is installed.

I prefer to use Hi-strength red Loctite and the liberal use of leverage.

Charles shipped the carrier to me in a relatively clean state so I will apply a special secret pre-paint conditioner. This helps the gloss black paint adhere amazingly well.


Triple boxed. Done. :)