So it looks like the 01-05 SC430 has a similar carrier as the SC, but the gear ratio for those years is 3.266 not the 3.769 I am after.

Bruce

 

I am just saying... go onto RHDJapan's website and look up the OS Giken 1.5-Way LSD for the JZZ30 Soarer and MKIV Supra TT Auto (or other JDM MKIV which also got the 200mm diff) and you will see the pricing I referenced. I've bought OS Giken parts from them before and had no issues.

Any OEM JZA80 Torsen LSD is going to be more expensive now than even in the past. Especially if it's a Torsen T-2. In 2011 I paid $1,000 cash after a long drive to the seller for mine (a T-1) inside an MKIV TT Auto 3.769 pumpkin. And even then they were ridiculously difficult to find for sale. I missed out on a few because I wasn't fast enough until I finally was able to secure a purchase quickly enough.

I have to disagree on whether an LSD is worth it or not. An LSD is always worth it. In 2011 installed my Torsen after having the pumpkin custom rebuilt with a 4.272 ring and pinion from a GS300. This was when I had a bone stock 2JZ-GE engine with my stock W58. Along with the other suspension, braking, wheel, tire, front seat and other changes I made to the car it was a night and day difference in the handling department... even with the stock 225hp (180whp). It helped make the car fun as hell compared to how it felt stock.

It changed the character of the car and made it more fun and easier to drive (and no I don't mean drifting around although you can do that with any LSD equipped RWD car). Compared to stock on the mountain roads I was frequenting I absolutely felt it was worth it. Now years later when I swapped in a boosted engine I did need to change the final drive ratio again but that's totally expected when changing from an NA to turbo configuration.

I've got zero regrets investing in an LSD as one of my earliest upgrades to my SC when it was stock non-turbo and I'm still using the same one now that the car is turbocharged.

I also have to respectfully disagree about whether an LSD is worth it especially when it comes to having a turbo 2JZ/1JZ with mild power. It very much is. In straight line acceleration (with a turbo and open diff) there is much more fine steering correction needed with an open diff as the power isn't being put down efficiently and in turns there isn't nearly the same control and stability when negotiating the apex of a corner once you apply throttle again. Accelerating through turns in an SC/Soarer/MKIV is more stable with any 1.5-way LSD.

The same applies to my low powered and short geared (factory 4.10:1) 230hp GR86 which came standard with a Torsen T-2 LSD. It's very much an important and very significant part of the car's driveline which enhances the handling and power delivery even though it's not at all a powerful car.

The Torsen LSD should have been a standard part of the SC300 5-speed or at the very least part of a factory handling package upgrade for all the SC's. None of which ever happened of course.

The OS Giken 1.5 is definitely a superior LSD and far better for high power applications and road racing and offers better control than the Torsen design can (even though a Torsen is still a good LSD). It is on my own list of long term upgrades that I'll get to for my SC300 once I've got my Haltech ECU sorted out.

 

I am happy to help when I can. Even before I bought my SC I learned from so many people and through years of ownership have been helped and educated by so many. It's always good to pay it forward whenever we can

I am glad to hear that your Mom is doing better now. I've also been there with a parent in the hospital not long ago and know it can be really tough. Wishing your Mom a strong and speedy recovery.


3.92 would be totally fine, just more aggressive than a 3.769 (which some like). Harvesting a 3.769 ratio for use with your W58 transmission (or an R154 later on) is the best balanced gear ratio choice.


Correct. The 2001-2005 SC430's got 3.266:1 ratios with their factory 5-speed auto transmissions. Same entire drivetrain combination that was present in 1998-2000 SC400's, 1998-2000 LS400's and 1998-2000 GS400's.

2006-2010 SC430's got 3.769:1 ratios with 6-speed automatic transmissions. But unfortunately the side axle design of the otherwise identical rear differential pumpkin also changed at that time (I had written about this in previous posts but needed a little memory jog-- there's so much information on these cars!). But the internals of the SC430 2006-2010 diff are still 100% the same. Edit/Update: My apologies but after further research sparked by the recent discussion in this thread I've come across some unfortunate evidence that suggests the 2006-2010 SC430 diff ring and pinion gears may in fact have slight but significant enough revisions so as to disqualify them from compatibility without employing precision custom machining work. See subsequent posts below for more detail.

So the thing to do if the price is right is to buy a used 2006-2010 SC430 diff, harvest its 3.769:1 ring and pinion and use that ratio when rebuilding (with an LSD at the same time) another differential pumpkin that is externally 100% SC300/400 compatible.

I did this many years ago in the inverse with a custom 4.272 ratio (from a GS300 diff) but for my then naturally aspirated configuration. I used that diff setup for 9 years with my naturally aspirated stock engine before I rebuilt it again with a 3.769 ring and pinion once I had a turbo 2JZ engine installed. That was very very worth it to me early on but I also didn't need to go for the lower ratio on a second rebuild for nearly a decade in between.

Since your 2JZ-GE is already an NA-T I'd go right to the final diff configuration you'll want. You'll only need to do this once in your case especially if you install a Torsen or OS Giken LSD.

OS's are clutch pack style designs but they reportedly last a VERY long time to the point that needing to rebuild them is rare. The OS 250R diff fluid changes at regular intervals is really your only maintenance item required.

Torsen LSD's (both T-1's and T-2's) being gear type designs require no maintenance and are considered lifetime designs. You just change the gear oil at regular intervals using the same synthetic type that an open diff requires (and with no added friction modifiers-- that kind of additive is for clutch pack based LSDs only).

 

A note on Torsen T-1's:

Torsen T-1's *can* break from *extreme* stress (usually at and above 500whp as many on SupraForums have observed over the years) which is why I said in previous posts to consider if one is going to be right for the long term of your build application. Everyone's mileage will vary and as we all know it depends on how the vehicle is used and driven.

Similarly this is also why W58's, while not ideal for turbo applications, have different long term results for people with turbo JZ engines: they are not bulletproof when they are given boosted power but it depends on what average power (really torque level and shock loading to the gears) they receive and how the driver treats them.

My SC has not been very high powered (currently 310whp and maybe in the near future up to maybe around 400whp) and probably will never be very high powered so technically I could stick with my Torsen T-1 LSD near indefinitely if I really wanted to. But if your build is not going to go up to 500whp or will stay well under that figure then a T-1, while an old design, will be fine.

It also depends on what kind of stress a T-1 at 500whp+ will encounter. Hard drifting, slam-shifting and hard drag launches? Then a T-1 at that power level and higher is not ideal or a great choice. A W58 won't be either for that matter. Spirited driving and reasonable launches with some respect for the drivetrain as a whole and below 500whp? Then a Torsen T-1 is fine. They're old but still excellent for many applications and are vastly superior performance wise to any open diff.

In rainy conditions they do require a little extra driving mindfulness and maturity to not over-drive for the conditions or lift throttle at the wrong times and good tires with good rain traction are highly recommended... but this is really nothing out of the ordinary for any 30+ year old RWD classic performance cars with LSDs and no electronic traction control aids.

 

Morning Craig,

Do you happen to know if the 3.769 ring and pinion from a 13-19 Lexus GS350 AWD rear carrier would fit in the SC carrier? Not sure if it is 200mm.

https://ebay.us/m/ZHUKhG

Thanks,
Bruce

 

That I do not know. The only way to be sure is for someone to take one apart and physically compare that ring and pinion with one from an SC/Soarer/MKIV/GS/Aristo. The ratio being numerically the same is promising and I have for some time theorized that some very late model Lexus vehicles with 200mm-ish rear diffs with Torsen T-2 LSDs and various final drive ratios might have internals that are compatible with our 200mm diffs... but it's not going to be known unless someone tries physically comparing the internals and taking some measurements.

So far SC430, LS430 and 90-95 LS400 internals are known to be compatible with those in our 200mm SC diffs. Outside of that we won't know until someone takes the risk and experiments.

Revision note: After much further research this advice must be scaled back to only the 2001-2005 SC430 and 2001-2005 LS430 rear diffs, both of which are 3.266:1 ratio.

Unfortunately after reading of some experimenting a SupraForums member did with a 2008 Lexus LS460 Hybrid rear diff (2.9x:1 ratio) which is externally the same as an '06-'10 SC430 and '06-'10 LS430 diff there in fact were minor but just significant enough differences in the internal ring gear such that there was incompatibility unless precise custom machining work were to be done).

Toyota/Lexus do re-use their various rear differential designs for a VERY long time even with minor external revisions. The GR86/BRZ's rear diff is basically a Supra MKIII and Cressida rear diff design from the 80's. Some of the more recent large RWD/AWD Lexus vehicles seem to use variations on the early 90's era 200mm diff design although as you've seen there are many significant external revision changes to their pumpkin housings over time that don't allow them to be a bolt in affair.

Still, we don't know for sure until a *possible* cross-reference part has been confirmed to be a fit for our SC diffs.

 

Ya. If I had an extra $200 I would love to buy one and check it out. It sure looks like the diff from a SC430.

Here are pics of an GS350 AWD:







Here are pics of a diff from a SC430:

 

^^ Everything looks dimensionally the same to me from the outside.

...And as a result I am going to apologize for and walk back my previous recommendation to look for a 2006-2010 3.679:1 SC430 diff.

Why? Well there's a big thread on SupraForums that covers the whole gamut of Supra JZA80, SC/Soarer and other 200mm compatible diff info for those wanting to swap gears with our differential housing family. And there has over the last years been some investigation into using more of the axle-stub-less versions of these diffs. I've participated there before and it looked like the 2006-2010 SC430 versions were fine internally alongside the 2001-2005 versions.

But also the LS430 diffs also previously mentioned in that thread only applied from model years 2001-2005. Notably just like 2001-2005 SC430 diffs the 2001-2005 LS430 diffs (and others of the same era in 200mm) usually retained the side axle stub design that SC/Soarer/MKIV/GS/Aristo vehicles used. The 2006+ LS430 diffs do not.

Someone in that big SF thread was very interested in the LS460 Hybrid's unique 2.9x:1 ratio for a transmission swap he was planning. So he bought one of the LS460 Hybrid rear diffs and opened it. As everyone had suspected every thing was *nearly* identical inside... but with one crucial difference with the ring gear having an offset difference of 11mm which made engagement with the pinion in a Supra MKIV (and similarly compatible) casing impossible without machining the gear. Apparently he was able to make it work when fitting a stock open differential but not when fitting an aftermarket Kaaz LSD.

See below:
See here and look for the two diffs shown side by side on Page 17 and his investigatory follow up post on page 18:

https://www.supraforums.com/threads/...age-17#replies

https://www.supraforums.com/threads/...608545/page-18

Also I looked up some cross-referenced ring and pinion part numbers that applied also listed in that thread and as you might have guessed it they were all interchangeable with our diffs until they got to the 2006 or so 200mm diff revision to not having side axle stubs.

So given all of this after some more research sparked by your own posting of those diff pictures I am going to assume that even the 2006-2010 SC430 diff may have this same ring gear revision despite having the 3.769 ratio. Again... there really is no way to know for sure unless someone buys one and tests the internal ring and pinion themselves with one of our casings. It is possible that the LS460 Hybrid diff ratio, being so unique on its own, was the only casualty in this revision but since the external casings are identical to those in the 2006-2010 SC430 and LS430 it has to be assumed until proven otherwise that the same ring gear revision may be present.

I'm glad you brought this up because it sparked me to look into it further. I am therefore going to revise my previous posts in regards to 2006-2010 SC430 diffs.

I am afraid this means your proven to be safe sources for 3.769:1 compatible ratios are actually limited to diffs from:

1993-1998 Supra TT Automatics
1996-2002 Supra SZ-R (JDM only)
Toyota Aristo V300 (aka 2JZ-GTE equipped Aristos) (JDM only)

There is the 3.615:1 ratio ring and pinion which can be harvested from a 90-95 or so Lexus LS400 diff for a custom rebuild. And the SC400's and GS300's 3.92 ratio.

 

Craig, NP on the SC430 thing. I had already purchased a diff for a GS300 with a 3.92.

I would still like the see what’s in the GS350 AWD. Maybe it’s similar to the R & P in the SC430?

Maybe some day someone will get the opportunity to open one up and let everyone know.

Bruce

 

^^ Glad you didn’t get into the ‘06+ SC430 diff yet Bruce. Again… it is entirely possible that the minor internal differences may not have been present yet in all early side axle stub-less versions of the 200mm differential housing.

I would love to see confirmation at some point comparing the later SC430 diff internals to SC/MKIV/GS internals. As for the GS350 AWD diff, is that known to also have a 3.77 ratio?

The 3.92 ratio will much better suit your engine and transmission configuration than your current ratio. It will still feel a bit “close ratio” with boost but nothing like a 4.08 or 4.27. It will allow you to actually build power through boost in each gear.