Pre-assembled V6 3rd has pinion leak and set shallow.
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March 22 2014

Anthony, located in Maine, has a 1992 3.0 with 5 speed....SAS...529 gears/lockright front/Detroit rear. 251,000 miles on the clock. He recently experienced a pinion seal leak from a pre-built 3rd that came from a large internet company.
With less than 450 miles on the rear 3rd, Anthony boxed it up and sent it 2,709.2 miles to me.
V6 3rd with 529 gears and a Detroit locker.
From the residual paint that was still there, he did not like the looks of the drive pattern.
I did a quick paint and all became obvious...drive side really does appear shallow and too close to the heel end.
Coast side is favoring the top edges....shallow.
Comet tail is tucked into the deep root.
Dis-assembly begins. Of note is that the carrier bearing adjusters were set tight just like they should be...good grade there.
Carrier bearing races are ok. Nothing special going on here.
"K TV6-529 1301" is stamped on the ring gear. Not 100% sure what to think of these gears yet.
I use 1 or 2 cans of ether per gear install to efficiently remove the gear oils. No smoking please.
The pinion drag feels 'notchy'....stiff at first and then frees up as it is turned. Wobble is not a problem with this one.
I measured about 18 in/lb of PPL start torq(break loose).
Has a 2 in/lb of rolling torque turning it slowly.
Turning it a bit faster the rolling torque increases to 5.
The pinion nut was on very tight(good score there).
The aftermarket seal is revealed.
There is a 'crinkle' near the upper left side. That might have caused the seal to leak.
The pinion is pushed out.
A solid collar was used.
A closer look at the wrinkle at the 10 o'clock position. The pinion bearing can be seen in the hole....what happened to the splashguard?
Just getting a feel how the old seal fits on the flange.....just a little looser than I am used to.
The flange is just like brand new.
The small outer pinion bearing is ok....the notchiness did not hurt anything.
I'm real curious what pinion shim was used...press the big bearing off.
A total of .071" was used....this explains the shallow paint.
The 071 will be replaced with this 080 shim.
Pinion bearing is pressed on. That nice, new Harborfreight 12 ton in the background is soon to go in my living room.
Now to put the pinion in the diff carrier.
The pinion nut is tightened with the electric impact until a modest 3 inch/pounds is measured.
Before the ring gear assembly is placed in diff, some checks are made. All 10 of the bolts were tight and they used loctite.
I didn't have to do this but I wanted to check the surfaces with a file and see how much run-out the Detroit has.
Surface filed and nothing unusual.
Pushing hard with the Chinese file I was able to actually make a few scratches in it.....usually I can't quite do that much scratching...not sure if I can use that as a criteria of the hardness of the material...is it SAE 8620 alloy steel or 4027? Who knows. But other than that, the surface was burr free and no unusual high spots.
Runout was just under .002"
The ring gear was a good, snug fit onto the Detroit. No press was needed or boiling water...just some love from the lead filled plastic hammer.
Threads are cleaned with ether and red loctite applied.
75 ft/lbs to all 10 fine threaded bolts.
Bearing cap bolts are snugged up fairly tight for this paint test.
The adjuster wheels are tightened to give some carrier bearing preload with a backlash of about .007".
Nice drive side. To me, the pattern is in the shape of a sports car. Now it favors the toe and is deep like it should be.
Coast is much better than before. I'd like to see it closer to center but it is what it is.
The comet tail is now somewhere in the middle.
drive---this is the reverse painted teeth.
coast
Now that the pinion depth is good, the solid collar and new OEM seal can be installed.
Skipped a few pictures but I had to re-shim the solid collar and had to tear it down several times to get it right. And now that it is, a good, used splashguard can be installed.
OEM 90311-38047 pinion seal.
A thick grease is applied to the inside to prevent the garter spring from popping loose.
The seal is evenly tapped in place.
I still shine a light inside to verify the spring did not pop loose.
Gear oil is applied to the effected seal surfaces to prevent a dry start up.
Threads are verified clean and red loctite on the pinion nut.
This nut is on very very tight. I only have a 2 in/lb start torque for pinion drag. We surely don't have to worry about these bearings getting hot for sure.
The Detroit locker case is now installed. Bearing caps are in place. A solid smack from the rubber end of hammer should result in a solid SMACK! sound of the upper tower cap seating down properly.
75 ft/lbs...
...and these wheel adjusters should turn easy if all is set down right and they did.
For my final adjustment, I smack all 4 corners while turning the pinion flange. This equalizes the carrier bearing tensions with each other.
I measure a combined pinion bearing plus carrier bearing preload of 10....2 for the pinion and 8 for the carrier bearings.
Backlash was measured every 3rd tooth and was about .006"
Blue medium strength loctite and 10 ft/lb
Final repaint....sweet drive pattern. In no way shallow....slight deep. Favors toe end.
Coast....good. Slight favoring of the heel.
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Going to Fedex to take a trip to Maine :)