LoveSCs

iTrader: (2)

Hey, I am looking into getting an LSD for my singled 1JZ SC400. First choice is obviously the MKIV LSD because it is the cheapest solution. However, my only concern with the MKIV LSD is safety because I have read of it getting uncontrollable if you lose traction.

So PLEASE, if you have or had one installed, tell me your experience with it. Have you ever had an "OH $***" moment, how much power are you putting down, and how has it held up....



Thanks in advance!

KahnBB6

iTrader: (5)

I have one. I'd say the main advantage of the Supra Torsen LSD is the ease of use. It only requires 30k gear oil changes like an open diff. No rebuilding down the road. At least I think it's 30k intervals. Great for cars well under 500hp.

Generally I find mine to be very stable, controllable and predictable. It's a huge improvement over the open differential. I have had zero issues and don't see it ever dying on me, especially given that I'll only throw up to 350-400whp at it eventually.

I have a 5-speed NA 180whp car with no factory traction control.

Yes, I've lost control before a couple of times. Every time it was on very rainy, slick California roads (which have an excess of tar buildup baked into the asphalt most of the year).

Once was with BFGoodrich KDW2 summer performance tires on a 20mph sharp turn that I downshifted into 2nd to negotiate. Car slid right sharply, I tried to countersteer and the Torsen threw it left VERY sharply and sent the car into a 180. Very frightening. But no accident happened. I was fine. Car was fine. Very shortly after I got rid of the KDW's after reading that they had horrible rain traction characteristics. GREAT performance tires but I later learned it's pretty much a "never in the rain" tire even on a racetrack.

Switched to BFGoodrich Comp2's after that. GREAT summer/rain tires.

One other time I had a similar loss of control by doing the same thing (on the Comp2's) turning right onto a street at perhaps 15mph. VERY slick roads. Downshifted into 2nd (NA's don't have much power as we all know) and the car stepped left a bit. I knew what was happening, reduced power and controlled it. Went on my merry way. It hasn't happened since and I still feel confident in with the Comp2's.

I also just take it easy and slowly if I have to drive in the rain. I allow no sudden build of horsepower from the engine in those conditions.

When in slick road conditions, don't downshift into turns, stay one gear higher than you normally would if you need to to avoid power buildup or boost. Unless you have a RaceLogic, ProEFI or other traction control system (or maybe even TRAC), just take it very cautiously in the rain. No sudden jerks of the steering wheel or aggressive downshifts for more power. Just don't drive as if you're invincible when the road conditions are slick. An STI or modern BMW turbo has electronic stability control to mitigate these issues and Torsens or other LSDs are still used. SC's with manual gearboxes and/or turbos rarely have traction control systems installed. And use a good set of tires that have good reviews for rain traction from performance car owners.

Also, I have found that the Lance Alignment that MKIV Supra owners swear by also did a lot to dial in more neutral handling characteristics with my car whereas stock SC300 alignment settings tended to make the car tail-happy even in the dry once I had an MKIV TT rear swaybar, a Torsen LSD and bigger tires swapped in.

From what I know about TRD 2-way clutch-type LSDs, you should still be similarly careful in the rain but they are thought to be ever so slightly safer..... in cars with 500+ horsepower. But the reason for that is different. Around 500hp+ it's just better to upgrade to an aftermarket LSD anyway.

I think you'll be fine. Some of us (myself included) have reiterated the cautionary experiences with our Torsens because we want people to be informed and aware of what to do and what not to do in averse road conditions when you have one-- not because we don't recommend them.

I drive with one daily and I never worry about it. When the roads are slick I drastically adjust my driving behavior to accommodate and I'm fine.

Good luck! They are hard to find. Keep looking!

(Aside, the later Soarer Torsen LSD is a newer T-2R unlike the T-1 design used in the Supra. It is supposed to be much more predictable and less prone to the behaviors we've discussed. Finding one, however, is a like locating a unicorn. And the gear ratio it has should almost always be 4.083:1 from R154 5-speed models).

LoveSCs

iTrader: (2)

Thanks for your input Kahn!!

I am looking to get into the 550-600rwhp range. But with a 1jz, so not so much torque as 2jz. I have a feeling I'm right on the edge, but I just feel as though I can use the $700 savings elsewhere if I can get the confidence that the MKIV torsen will work for me. I only drive on nice days, so I don't anticipate driving in slick conditions. Thanks again

KahnBB6

iTrader: (5)

You're welcome! Glad to help.

Staying out of slick conditions will already reduce your chances of unprovoked loss of traction to near zero but it's not so much the torque but the speed at which the power comes on. If you're already thinking about 600whp I'd still recommend you look into a TRD 2-way LSD. Nearly all Supra TT owners feel it's better all around for performance and predictability past 500whp. Even at the dragstrip it seems like going well beyond 500hp with the Supra Torsen is pushing the limits of the diff. The passive gears supposedly don't react as efficiently past those power levels. At least with the T-1.

If you want the best of both worlds and money is no object (which of course it always will be), then the OS Giken Super Lock LSD is a good bet. It's a clutch-type but has extremely good long term wear characteristics and is technically classified as a 1.5-way like the gear-type Torsen T-1 and T-2R. Great end-all-be-all option for MKIV roadracers.

The TRD 2-way is much cheaper though

I don't mean to say you can't use the Torsen even with a lot of power. Just be aware of the pros and cons once you get to 550-600+ whp. Search on SF and there are many anecdotes from highly modified Supra TT owners.

LoveSCs

iTrader: (2)

Thanks again Kahn! I guess it might be worth the extra $$ to keep myself from swerving into oncoming traffic! But when I think of that $700, I think of cams and a torque converter rebuild haha. I might just end up going with the TRD, unless I can gain some confidence from other members that say that they are pushing some decent power through theirs without issue

Does anyone else have any input?