theman

Incorrect. I have done plenty of looking it up as well in my times since the interweb... I am talking from first hands-on experience. There is enough drag on the factory LSD to find out what it is by hand as it acts entirely different compared with the standard open diff.
But yes, if you want to take a chance online in purchasing, best to see the internals or originating VIN.

mikef

iTrader: (3)

If you turn one side of a torsion the other side will turn the opposite way, but you will feel some tightness if you turn it all the way around, like a snag kinda feel but not really a snag lol

KahnBB6

iTrader: (5)

I did not know this and I have one in my car. Thanks!

I'll add something for the OP purely for informational value (and this is academic because it's been proven incompatible for us) but the 1st gen IS-F rear differentials look VERY similar to the MKIV Supra, 1st gen SC, 2nd gen SC and GS300/400 diffs. I brought this up in an IS-F diff thread regarding swapping Torsens into the early year cars that came without them. Toyota definitely reused the design but they modified it a bit to suit the new chassis-- so I'll be clear that you cannot use an IS-F Torsen LSD diff in an SC. Moreover I'm sure they go for a fortune anyway. Interesting nonetheless though because they are far more similar to an SC diff than an MK3 diff is to an SC diff.

BAD954BOI

iTrader: (5)

I've been looking for the torque spec for that 35mm nut and cant find it anywhere?

also, when swapping the flange i read a lot of talk about making sure the preload,backlash, and something about a mesh that should all be aligned.

can someone please enlighten me with the dummy version and if that applies to me?

a little more info:
my situation is kind of odd i have a soarer r154 along with jdm drive shaft.. bolted directly to the na diff.. cant remember if i had to muscle it or if it lined up perfectly.. that my also explain the slight vibration

oldManTan

when i bought my SC400 i was told it had a supra auto diff, i didn't really care or know exactly wat it is but i've tried everything to check it but just can't figure out how. the wheels spin in different directions if i spin one, if someone holds one wheel and i spin the other, they lock and spin in different directions, if i spin the driveshaft, then both wheels sometimes 1 more than the other will spin. torsen is torque sensing so does it only work when there's enough torque being applied to the wheels ie the weight of the car? i'm just gonna have to park one wheel in a puddle and the other on dry and floor it to see what happens. my diff also clicks, here i have a video, it's not noticeable when driving or anything...



EDIT: the metal on metal rubbing is my brakes, i have supra calipers and the brake pads are too big for the rotors and they have a lip and they rub on the rotor, i file the lip down periodically and i'm getting bigger rotors ASAP lol.

czar07

Sorry buddy, but you are wrong. The SC was not top the top level coupe for Toyota. That was the Soarer (same **** right?). And the Soarers did have LSDs as an option. NA Supra also has optional LSD.

SCereal

iTrader: (4)

That all has to do with the ring gear and pinion setup. It's the relationship between them to ensure they're correct and not binding, etc. On some diffs when you muck with the flange/ujoint mount it changes how the pinion is sitting in the diff which effects all that. I have no idea if that's the case with our diffs but it seems not to bother it as plenty of people swap the flanges and never mention having to adjust the gears.

xtra

We usually get a 35mm socket onto the nut and tighten the exact amount of rotation needed to take the nut out. To be precise, make sure the pin on the nut matches the impression on the shaft.
The diff are preloaded from the factory so doing it that way gets you pretty close to OEM spec.
The best way to have it done is to tighten and regularly check the preload using a torque wrench that can reach in/lbs. I believe the starting preload is about 25 to 30 lbs. Loosen of more and tighten till less till you get the desire preload pressure.

Ali SC3

iTrader: (10)

Yeah you can't ignore it completely it leads to premature failure of the diff if it is over torqued or too loose.
The idea I have always heard was not an exact number but when you take it off you get a feel for the force and count the number of times you spin it to take it out. then do the same number of rotations putting it back in.

soarer93

I hope this following table and write up helps a little for some of you whom are wanting an LSD.
*and corrects the OPs statement about the supra non turbo NOT having an lsd... it did in some models, most infact*

For the Supra:
this table shows the non turbo and Turbo models - it shows what Diffs each had.
Pay attention to the AO1B That will give you a 4.083 Diff Ratio -
Now.. if you are wanting the 3.769 Ratio then get the A02B etc. But it has to be

Heres something to keep in mind -
If you are getting the Torsen Unit itself and not the whole differential assembly with its casing..
(see picture of item below the Table)
You need a 10 bolt 8" Crown wheel. So you can grab one from a few different Supra Models.
You will have to open up your Differential and slap it in.. BUT theres a catch..
depending on which 8" 10 Bolt you install, you have 2 options again...
Live with the slightly different gearing ratios.. OR Swap your Pinion and Crown Gear from your existing Diff, and you will Keep the Existing Diff Ratio that your vehicle came with.
That allows for no variation in the Speedo, And a higher Diff ratio will accelerate faster but have less top speed..

Note:
With any diff change, you must reset the bearing preload, and gear lash according to Toyota's procedure.
No two housings, and no two diffs are ever machined exactly the same, and when having the gear mesh too tight, or too loose by just a few thousands of an inch will cause gear noise, and wear, they have to be reshimmed to make sure they are within spec.
If you do not have a dial indicator to check gear lash, and a micrometer to check shim thickness, it just may be easier to take your housing, with the old diff out, and the LSD with your ring gear already bolted to it, to a shop that is equipped & experienced in setting gear mesh"

but the main thing is is you grab a 10 bolt Torsen Diff from a Supra -
use this table as a guide.

KahnBB6

iTrader: (5)

That chart doesn't correctly list 93.5-96 Supra MKIV NA's as having 4.272:1 gear ratios (few of which had Torsens as rare options). US market 97-98 MKIV NA's had the 4.083:1 ratio (and similarly extremely rare to find helical gear LSDs).

If this chart represents JDM Supras it's a bit more accurate. All of their NA's had 4.083:1 ratios from 1993-2002.

The important part is that you want the Automatic TT diff (and inspect it before buying) or a JDM TT 6-speed 200mm Torsen diff (export models to the USA, Switzerland, UK, etc. were the only models with the 220mm big LSD diff).

Ali SC3

iTrader: (10)

good point, in the US the supra N/A auto and 5 speed both share the 4.27 ratio from 93-96.
Only the sc300 5 speed n/a's have the 4.08 ratio like the JDM models in that year range.

Thats why a supra n/a feels a bit quicker in gearing than a sc300, its not just the weight.

soarer93

well that's good info to add to that then - can make up a chart later with that - I never thought to look up US market specifically -
Canada never had the NA Supra - just the Turbo - and all came with LSD -

but for point of reference then..

92-97 SC300
6 cyl, AT (4.27 ratio)
6 cyl, MT (4.08 ratio)

if you were trying to match up -
but correct that if it needs to be.. we also never had the sc300 here either..

theman

How was my statement wrong? You just said it, the LSD was a seldom selection OPTION... they are very rare in the base cars of their top tier coupes, Supras, SCs/Soarers alike. The LSD should have been standard even at base level.

theman

Unfortunately this is not the best way to go about torque on that nut... you want to stick right around the 20# max torque on that nut... it really doesn't take much, and that is the sweet spot number between the NA and turbo rear ends. You want to have a good feel for how the diff turns by hand before taking off the old yolk so you know how it should turn putting on the swapped yolk. Once the swapped yolk is on start at 17lbs, feel it, and if all turns as well go to 20lbs and you're done.
You can find these torque settings in the Factory Manual under the diff section... I'll see if I can grab a pic later for you of the page.

If you want to delve into the whole basics of doing Diff work, here is a decent read...
http://www.differentials.com/technic...n-instructions