Returd

you're correct in correcting me. I've been using a dab of white lithium grease as my mark and it got transferred. It is indeed 12 and not 13 teeth

so after all of this count/recount stuff the bottom line is I don't swap the gear set is that I'll be going from presently 3.92 to 3.26 in the torsen housing.

gerrb

iTrader: (34)

^^^ since you have a 1992 SC400 and I assume the A340 auto transmission , then staying with 3.92 gear ratio will be better.

Just use the torsen LSD in combination with the parts 1993 SC400 ring gear / pinion . You can probably install both on the cleaner pumpkin or either way since those are both same pumpkins.

You keep same gearing but with an LSD for your diff.

Returd

I'm leaning towards lazy, that is use the the torsen diff as is.

KahnBB6

iTrader: (5)

It goes against less work but if you were to rebuild the Canadian 3.92 diff with the LSD then you would have a true factory type configuration since according to that JZA80 diff info thread some Canadian market SC400's had a factory Torsen option

Returd

Hmm. I'll sleep on it. Now I'm going to have to go to the local yard where there's a 95. Do you think a reasonable test to see if it's a torsen would be to spin the shaft and check if both axle shafts move? I don't relish the thought of dropping a rear end in a yard without air tools but It'll keep me awake thinking there might be a torsen close by for cheap. I don't suppose any LS400's had them as well? There's a 95 LS close by also.

Returd

I don't suppose any smarty pants here can do the math and tell me what the rpm difference will be at 60-70 MPH between the 3.92 versus the 3.26 (assuming correct wheel size and stock transmission). Off hand I don't even remember what the rev's where at 60mph.

Returd

I ordered bolts and seals etc and will be doing the change over.

gerrb

iTrader: (34)

NO . A torsen LSD doesn't necessarily make both rear axle move when the drive shaft is rotated.

It is torque sensing , it makes the other move when it senses the need.

Returd

any thoughts on an easy way to determine if it's a torsen? All I can think of is pulling a drain plug and fishing in a boroscope.

gerrb

iTrader: (34)

^^^ only way for a torsen is checking what is inside the pumpkin ... no other way

RXRodger

iTrader: (2)

If you find a Torsen in a junkyard car for cheap, stop by on the way home and buy a megaball or a ticket for whatever your lottery is. That would truly be huge win.

KahnBB6

iTrader: (5)

^^ This. The only way to know is to pull the differential from the car and open the rear aluminum cover to see if there is a regular open diff or the Torsen LSD in there. This is why when we buy Supra TT Auto 3.76 Torsen pumpkins it is customary for the seller to show a picture of the diff's interior with the cover removed (and probably some piece of paper with their user name in the shot) to confirm that a Torsen is really in there, since 97-98 TT Autos had it as an option. The same would apply with any Supra MKIV NA Torsen pumpkin (early 4.272 or later 4.083 ratios) which are incredibly rare to find.

If you have a boroscope small enough to make it through the diff drain plug area maybe you can do that, too but you'd have to know exactly what you're looking for. And of course it would have to be drained of old fluid first. If it can be done it would be easier, certainly.

I've searched on Google and so far the only thread that has given the information that Canadian SC400's had LSD's from the factory is the one large one on SF that I posted above. By now if no one there corrected it as misinformation I'll believe it as truth but it also doesn't say whether or not this was a standard Canadian SC400 feature or just an option (including rarity if it was). I can understand why it was offered due to the more severe weather in Canada's winters. The Torsen was also a factory option for 1UZ Soarers, or at least for some of their model years and trim levels with the 1UZ.

Nonetheless, standard or optional Toyota/Lexus kept the same 3.92 final drive ratio for all the non-VVTi 1UZ models.

LS400's never had Torsen LSD's as options. I know that some kind of LSD's can be fitted into them VIP drift builds but they never had them from the factory, no. Perhaps the sister JDM Celsiors had a Torsen option for some years but if so I've never heard of it. For our purposes with open-diff SC's that is a dead end.

Returd

I just spotted a Ford 8.8 conversion thread. Had I known this was an option prior to swapping in this supra torsen I'd have converted. The Lexus shimming design for mesh/backlash isn't the best out there, and I have four Ford diff's for my Mustangs.

2013FSport

iTrader: (2)

Hey I don't want to derail this thread but I'm looking for insight on a LSD swap for a USD 2012 IS-350 and their is little information out there. If I start a new thread I would like to invite a couple of you over.
I've set up 40 some odd diff's and haven't botched any yet however all are American stuff. Ford 9" (easy ones) 8.8", GM 10 and 12 bolt, Dana 44, 60, 70 ect... but never Japanese. I've done a bit of research checking PN's and doing the Where Used to find some conflicting info.
Any help would be appreciated if you know about the IS series. Thanks!

Returd

treat the Japanese the same, they all are subject to the same forces, clearance needs etc. Frankly my little experience with the Lexus diff shows me that the Ford 8.8 is easier, and the 9" super easy. Personally I'd be looking into a swap to domestic. I'm most familiar with the 8.8 and am unaware of a 9" for IRS. A torsen T2r for 8.8 brand new $687 over at Maximum.