Torsen LSD for Carol's 1990 Pickup
(42 BIG pics loading)
OCT 21 2020

Yes....I procrastinated this write-up for 2 years and 2 weeks :)
Carol chose an interesting packing material to send the 3rd plus parts...
But all these clothes did the trick. Made the long trip from NY to AZ just fine.

Long story short...the diff was a 3.42 ratio. Won't accept 390 gears.
I found an old 410 8 cyl 3rd to do the job so all is good.

I believe the 8 inch Torsen is rated for up to 1000 horse power so all is good there.





New races installed.....

The Richmond brand 390 ring gear is checked for any unusual rough spots and all is good.

Red loctite and 70 ft/lb.

Richmond gears usually have a very wide .010" backlash like this one.


1.520" pinion head means a "4 cyl ring and pinion"....No loss in strength compared to a "V6 ring and pinion"
but this can affect what thickness of pinion shim is used.
example---.076" vs .237"

.093 is the chosen starter shim.

The pinion head was contacting the Torsen so a flapper wheel fixed it.

Thread engagement is much less than on the right side.
At least it's good to know that the most of the straining forces are also on the right.



1st paint test...DRIVE.....looks a little shallow.

COAST.....could be shallow.

Comet tail....hugging the root hard and that means it is shallow.

Teardown and add .010"

The little 12 ton from Harborfreight is easily up to this job....and hundreds of other similar jobs in recent years.

mounting the pinion.....

Now this is much better. This is the DRIVE side and is no longer shallow.

COAST nice

Reverse painted DRIVE.....nice.

Reverse painted COAST....good.

comet tail does not say much this time.

With depth set now to set the solid collar. On the 3rd try, I nailed it.

I now prefer only Genuine factory seals. All my leak reports went to zero after using factory part numbers.

Recessed between 1.5~2.0 mm.

Flange is wet sanded with #1500 sandpaper. A generous amount of anti-seize on the threads.

New flange nut.....

Tighten and measure a smooth 10 inch/pounds of pinion bearing preload.

A final check and tighten the 4 bearing cap bolts to 70 ft/lb.



Heavy duty bubble wrap and packing paper to keep it from shifting around.


59 pounds heading to East NY.

Notes of the install.