LSD center into open diff

vincentvega · Post by **vincentvega** » Wed May 02, 2007 2:45 pm

Can anyone point me in the direction of info on how to swap a viscous LSD center into an open diff?

I know the info has been posted a few times but search isnt turning anything up...

I need to swap a viscous LCD center from an aus RS into a 3.9 NA liberty open diff.

cheers

BrennyV · Post by **BrennyV** » Wed May 02, 2007 3:06 pm

im fairly sure if you talk to andrewt he can give you all the right info, andrew put a rx lsd into his berty diff

AndrewT · Post by **AndrewT** » Wed May 02, 2007 3:06 pm

Basically you need to swap the LSD centre into the OPEN diff casing and use that casing in your car.

Heres what I recall from going one a while back.

- Remove back cover from LSD diff
- Remove stub axel bolts (requires special socket, can get from Snapon)
- Remove stub axels
- Remove the two parts that hold the stub axels (these also hold the centre in place) - I forget what these are called sorry
- Remove LSD centre
- Put the centre in a bench vice - remove ring gear (this is what determines the LSD's ratio).
- Put the LSD centre to the side

- Remove back cover from OPEN diff
- Remove stub axel bolts (requires special socket, can get from Snapon)
- Remove stub axels
- Remove the two parts that hold the stub axels (these also hold the centre in place) - I forget what these are called sorry
- Remove the open centre
- Put the centre in a bench vice - remove the 3.9 ring gear.
- Put the LSD centre into the bench vice
- Install the 3.9 ring gear onto it
- DO NOT use a rattle gun to tighten these bolts - they must be torqued up by hand.
- This *might* require enlarging of the bolt holes on the LSD centre. Some models have smaller diameter holes.
- Reinstall the LSD centre with it's new 3.9 ring gear into the 3.9 OPEN diff centre.
- Be sure to use LSD oil not just normal diff oil.
- Your choice which back cover to install, the one with the stick that says 3.9 or the one that says LSD (personally I think it makes more sense to put the one with the correct ratio).

Back when I did mine somebody posted a link to a thread on USMB which had some diagrams.

bluesteel · Post by **bluesteel** » Wed May 02, 2007 3:20 pm

i did exactly that last night, swapping a lsd centre into an open diff

i have one question tho

do you use the shims that came with the casing your putting the diff into... or the shims from the casing from the LSD

vincentvega · Post by **vincentvega** » Wed May 02, 2007 4:17 pm

excellent, thanks guys.

showthread.php?t=4177&highlight=USMB+diff

http://www.ultimatesubaru.org/forum/sho ... hp?t=49919

http://www.ultimatesubaru.org/forum/sho ... hp?t=66430

search words: limited slip diff LSD swap ratio grind

AndrewT · Post by **AndrewT** » Wed May 02, 2007 4:46 pm

Use the shims that match the casing. This lines the ring rear up with the pinion the same as it was before.
One way to check the allignment is to smear toothpaste on the pinion then assemble it and turn the diff by hand. Disassemble again and check the imprint of where the gears mesh. It should have as large a possible contact area otherwise the diff will whine.

If you want it to be perfect a diff specialist can re-shim the diff to ensure complete 100% allignment.

bluesteel · Post by **bluesteel** » Wed May 02, 2007 5:03 pm

cool... i guessed to use the shims to match the casing too

putting it in tonight... so we will see

cheers

vincentvega · Post by **vincentvega** » Tue May 08, 2007 10:56 pm

I stripped the LSD diff this evening. all came apart no problem.

One question though - how do you remove the pinion shaft from the diff housing? Or are they a mated part?

The reason I ask is i have a guy wanting to convert his diff to 3.545 - I was planning on sending him down the ring gear and the pinion shaft.
I guess i have to send him the whole diff housing so that he gets the 3.545 pinion?

Also - where was the need for the E10 torx socket? Or is this only required for 4.11 / 4.444 diffs?

bluesteel · Post by **bluesteel** » Tue May 08, 2007 11:31 pm

the e10 socket is for taking the stubbs out on the earlier diffs (it is inside the hollow stub thingy)

and the pinion shaft... is that the big nut on the bit that bolts onto the tailshaft? not sure.. havent done that one

vincentvega · Post by **vincentvega** » Wed May 09, 2007 9:13 am

the big nut holds the tailshaft flange on. I took that off but the pinion shaft is still locked into the housing

bluesteel · Post by **bluesteel** » Wed May 09, 2007 9:22 am

BFH?

jkhgjhgkjhgkhgjh

vincentvega · Post by **vincentvega** » Wed May 09, 2007 9:28 am

i have tried a SFH

im not game to use a BFH until someone tells me thats the correct way to do it