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Just got an LSD for my build. How will this change my driving experience?
Just got a MKIV Auto TT Torsen Diff for my build. Outside of the obvious traction on launch how will this change my driving experience? How about in the rain?
Please link me if you know of great reading material about real world use on our cars.
The car is a 95' Sc300 NA/T starting at about 500hp and maybe 6-700 after standalone, twin disk, fuel etc.
You'll immediately notice a feeling of having the car push a bit in the rear during cornering and of course there will be more consistent straight line launches. Mostly it's how it feels in the turns, though. Night and day from the open diff... but also very unobtrusive when driving at 2-3/10ths. The Torsen is barely there until you begin to push the car. Tailslides are more controllable and it's easier to get through twisty sections of mountain road with slightly less steering input. Also, the 3.77 gearing will be more ideal for fuel economy. How the R154 gearing matches up with that ratio I cannot yet comment on but most folks seem to love the combination.
Being a Torsen T-1 and not the newer preloaded T-2 design be aware that once one of the rear wheels becomes unloaded you have an open diff until both wheels are on the ground again. This almost never happens with an SC/MKIV unless you are on uneven ground on a mountain.
Now rain is the one thing I want to warn you about. Have tires with GOOD rain traction and be gentle with the car in rain. There is a tendency, especially around 500hp (but I assure you I've experienced it with a mere 180whp NA), for the Torsen to make the car step left under certain conditions in very low traction situations. You really have be aware of this and not make and sudden throttle inputs while driving in the rain (or downshift into 2nd or 3rd for more power suddenly). Once you've experienced it you will understand how to avoid it, though turbo compressor surge might cause the issue as well. I am describing worst case scenarios to you.
Most MKIV guys tend to consider 500whp as the cutoff point for the Torsen LSD as a reliable unit under that amount of power but they also feel that it can be unpredictable in rainy conditions with 500whp or more. The common upgrade at that point is the TRD 2-way clutch-pack LSD because it is more consistent in behavior with high horsepower JZ's and more durable at those power levels.
If you're considering a standalone ECU like a ProEFI, seriously consider looking into an aftermarket traction control option.
Generally I think you will like this LSD but do be extra careful in the rain with that kind of power, and take a look through some SF threads regarding the generally agreed upon safe horsepower ceiling for the 200mm (and 220mm) Torsen T-1's.
Aside, a T-2R was made available for JDM Soarers and it does not have the potentially twitchy characteristics in the rain or on otherwise slick roads.
For what it's worth I enjoy my T-1 in all conditions and have zero trouble. I have no traction control system yet. I just cool it and drive calmly and slowly with no sudden inputs in the rain. However, aftermarket traction control is on the table for me once I get the turbos in. In the dry, it's fine. Hope this helps a bit, Studiogeek!
Kahn,
Man you were exactly who I hoped would answer this! Thank you so much! That helps big time.
Lucky thing is I have so much respect for the dangers of low traction situations, it makes me a legit Jeckyl and Hyde. I spun out on a metal bridge in the rain over 30 years ago and it never stopped influencing my wet weather driving. It's almost over the top......
As far as I have read, Its pretty easy to stay out of boost if you keep the rpm's down. I watched some Pro Driver videos years ago. They got me going for smooth at all times in all ways.
So if I am drivng like someones Grandmother in the rain as usual, are you saying its actually MORE squrrrely then the open diff? Or are you just saying trying to do more than I generally would because it's an LSD will bite?
Thanks Again,
I seriously appreciate your input...
SG
If you really want to feel the difference I'd get the TRD diff and replace that Torsen. At over 500whp it is one of the best mods you can do. When the Torsen breaks loose the car will want to dart in one direction or the other. The TRD keeps the car straight.
If you really want to feel the difference I'd get the TRD diff and replace that Torsen. At over 500whp it is one of the best mods you can do. When the Torsen breaks loose the car will want to dart in one direction or the other. The TRD keeps the car straight.
Steve K.
I thought the whole idea of the LSD was less darting side to side, keeping the car straighter and more predictable in turns than open diff.
Are you saying it darts more than an open diff or that the TRD darts less than the torsen, but both dart less than open diff at the same power?
Studio, an open diff was designed to put power to the wheel that looses traction so in condition when you loose traction its more of a safer experience or will bring you to a stop quicker, as in the wheel that has traction looses its power while the other wheel tries to recover its traction and this keeps a rwd car from "spinning out" sideways as fast because the wheel that has traction is stopped to match the wheel that doesn't. usually you can let off and still regain control in this type even in rainy conditions, you will experience it sliding out a little and after lifting off an open diff will "catch" you and help you recover within reason.
with the LSD when one wheel looses traction it does not get all the power till it regains it, it only transfers a hair more power to the wheel without traction. so lets say in the rain you start to loose traction on the passenger rear the car will want to go sideways very quickly as the drivers wheel is still laying down most of the power it was before (a little gets taken away aka "limited" slip). this is why high hp cars with LSD and rain do not mix. some people wont even take theirs out if the forecast has rain in it. once you start sliding in the rain its bad news, the idea is to not get into that situation when its wet, cause the LSD won't catch you like an open diff, you will have to know how to countersteer to regain control if you are still on the gas and fishtailing becomes a very real worls possibility (I once pulled an accidental 270 degree turn in my lsd equipped 240sx in an intersection and miraculously didn't hit a thing but it opened my eyes in that department, let me tell you an accidental turn of any degree is not fun). thats why every modded 2jz owner drives like a grandma in the rain.
even out of the rain whey you have a LSD equipped car that can spin the wheels easily (400hp on twins can easily spin even in 3rd) you can get into the situation where one will slip and the other will catch and the car sort of tweaks a little each direction depending on which side is slipping. the wheel wont keep slipping due to dry conditions and here its just the power is too much for the tire, but your natural response might be to lift off and try and save it like you would on an open diff, but under "DRY conditions" its often preferred to power through it while slightly lifting off the throttle and counter steering to regain traction, that way the wheel without traction can catch up and keep you straight again, cause if you just let off and brake while you don't have trac on the slipping wheel you might just end up a decent amount sideways as well. everyone has their own style though. so lifting off is not always as usefull with an lsd as it was on oyour open diff, I know on my open I can push the throttle down and kick it out a little in the rain, but I would never, and I repeat never try that with an LSD unless I was on purpose trying to drift.
best advice is find a very very open parking lot, and give it a test out. power over the thing until you learn the difference going sideways. loose traction and then lock up the brakes, try out things you might be worried about. on a wet day if you do it you will see how floaty the rear will become on you, I have an open diff in my SC and I don't go more than 35% throtlte in the rain as it literally starts spinning one wheel and the back end will move either to the right for me. With LSD it would move much faster and is harder to catch. I actually haven't bothered to install a LSD yet because it takes more attention to drive the car, Lexus stopped putting LSD standard on newer models because its more dangerous if you don't know how to drive one. they also started making the newer models understeer on purpose but that is a whole different discussion.
LSD is helpfull for performance driving, burnouts, drifting, all that good stuff, but its important to understand whats going on because it inherently makes a rwd potentially more dangerous if you don't know how to drive with one.
I thought the whole idea of the LSD was less darting side to side, keeping the car straighter and more predictable in turns than open diff.
Are you saying it darts more than an open diff or that the TRD darts less than the torsen, but both dart less than open diff at the same power?
Thanks 1A1
TRD doesn't dart at all is what I am saying. IT puts the power down to both wheels instead of one like the Torsen does. Torsen is better than an open diff, but the TRD is much better than the Torsen.
I watched some Pro Driver videos years ago. They got me going for smooth at all times in all ways.
I haven't heard of it but it sounds like great advice! Also, with that kind of power, have some 275's out back I personally like BFG Comp2's for all-weather (no snow) traction and dry fun. The now discontinued BFG KDW2's are what once scared the daylights out of me in a sudden 360 in the rain with a Torsen in the rain. At 25mph. So avoid anything like that which performance car people review as having "bad rain traction".
Originally Posted by Studiogeek
So if I am drivng like someones Grandmother in the rain as usual, are you saying its actually MORE squrrrely then the open diff? Or are you just saying trying to do more than I generally would because it's an LSD will bite?
No, problem. Any LSD is far, far better than no LSD in any sportscar. I don't care what it is. LSD's definitely help to put power down in a more efficient (and fun!) way and help tremendously with cornering and your driving line.
What I meant was that the T-1 design has a tendency to be just a bit squirrelly under *some* driver inputs in rainy/low traction situations... especially with boost. Yes, it can under certain conditions get away from you in the rain under power, mostly with a slight step to the left that will confuse you as to your steering correction inputs.
Torsen LSDs are still used in a lot of cars but they are all the T2, T2R or T3 varieties. And I do think this twitchy tendency is one reason MKIV TT's and Soarer 2.5 GT's had the TRAC system as standard as an insurance policy. But in swapped/modified SC's we usually don't have electronic traction control for the wet.
I think your "grandma style" safe driving habits in the wet are fine and good. Just take note that Torsen T-1's can have this tendency under certain slick conditions
Originally Posted by 1A1
If you really want to feel the difference I'd get the TRD diff and replace that Torsen. At over 500whp it is one of the best mods you can do. When the Torsen breaks loose the car will want to dart in one direction or the other. The TRD keeps the car straight.
Steve K.
^^ I have to agree with Steve when you're at 500whp or above. The TRD LSD (2-way clutch-based vs the Torsen 1.5-way gear-based) does much better with very high horsepower engines and does not exhibit the same twitchiness in the rain. But it is also largely the power holding of the Torsen (as designed for the JZA80 and JZZ30 chassis) at those power levels. Questionable rain characteristics aside, 500whp is fine (as far as I know) but that may be the theoretical limit for its reliable power holding. I know that Torsen T-1's will break at a certain power level after repeated runs and that may be getting close to that limitation. At a mere 300-400whp they should last indefinitely.
The Torsen T-2R from a Soarer also doesn't have the same negatives of the T-1 but they are of course very hard to find and probably still don't have the maximum power holding of a TRD LSD or other beefy clutch-pack LSD.
I'm sticking with my T-1 because for low NA power it's perfect and for the low 360whp and aftermarket traction control I'm building for I see little reason to swap it unless I find a deal on a used T-2R. Studio, if I had your project I'd be looking into a beefier LSD.
Originally Posted by Ali SC3
....on a wet day if you do it you will see how floaty the rear will become on you, I have an open diff in my SC and I don't go more than 35% throtlte in the rain as it literally starts spinning one wheel and the back end will move either to the right for me. With LSD it would move much faster and is harder to catch. I actually haven't bothered to install a LSD yet because it takes more attention to drive the car, Lexus stopped putting LSD standard on newer models because its more dangerous if you don't know how to drive one. they also started making the newer models understeer on purpose but that is a whole different discussion.
LSD is helpfull for performance driving, burnouts, drifting, all that good stuff, but its important to understand whats going on because it inherently makes a rwd potentially more dangerous if you don't know how to drive with one.
^^^^^^ Ali's ENTIRE post is right on the money. Thank you!!! Well worth a couple of re-reads and a very thorough walkthrough of the differences in differential types and the potential issues with LSDs if you don't know what you're doing. I also agree that finding a parking lot where it's wet and practicing a bit to understand how differently the rear end will react is a good idea.
As far as I know with Lexus, only the IS300, RC-F, IS-F, a GS F-Sport model and an LS460 F-Sport model (I can't recall what they're called specifically) and the upcoming Euro IS200T have Torsens as options... but they are a more modern T2 design and traction control is a universe of improvement from what Toyota had in the early 90's with "TRAC". Some Toyota trucks and the FJ might have had them too but that's a different kind of application.
Similarly, all FR-S and BRZ's have Torsen T-2's and low traction Prius tires but they also have a tremendous amount of traction control standard... which can be turned off but this has to be a conscious action on the part of the driver.
Same goes for Torsen equipped Mustangs, etc.
Also, Toyota pretty much owns the corporation that makes Torsens and the IP for all variants under the brand.
Modern advances have largely mitigated the issues we are speaking about in moderately powered cars (though ultra high horsepower and rain still do not mix well-- even for something like an R35 GTR under the right circumstances) but we are dealing in vintage cars that do not have all those modern traction control advances. We use what works within our budgets in the SC world, so as a minor consequence unless we've added some pricey gear to the cars we have just as careful just as in the past
Last edited by KahnBB6; 08-07-15 at 03:16 PM.
Reason: Grammatical correction and additions
Studio, an open diff was designed to put power to the wheel that looses traction so in condition when you loose traction its more of a safer experience or will bring you to a stop quicker, as in the wheel that has traction looses its power while the other wheel tries to recover its traction and this keeps a rwd car from "spinning out" sideways as fast because the wheel that has traction is stopped to match the wheel that doesn't. usually you can let off and still regain control in this type even in rainy conditions, you will experience it sliding out a little and after lifting off an open diff will "catch" you and help you recover within reason.
with the LSD when one wheel looses traction it does not get all the power till it regains it, it only transfers a hair more power to the wheel without traction. so lets say in the rain you start to loose traction on the passenger rear the car will want to go sideways very quickly as the drivers wheel is still laying down most of the power it was before (a little gets taken away aka "limited" slip). this is why high hp cars with LSD and rain do not mix. some people wont even take theirs out if the forecast has rain in it. once you start sliding in the rain its bad news, the idea is to not get into that situation when its wet, cause the LSD won't catch you like an open diff, you will have to know how to countersteer to regain control if you are still on the gas and fishtailing becomes a very real worls possibility (I once pulled an accidental 270 degree turn in my lsd equipped 240sx in an intersection and miraculously didn't hit a thing but it opened my eyes in that department, let me tell you an accidental turn of any degree is not fun). thats why every modded 2jz owner drives like a grandma in the rain.
even out of the rain whey you have a LSD equipped car that can spin the wheels easily (400hp on twins can easily spin even in 3rd) you can get into the situation where one will slip and the other will catch and the car sort of tweaks a little each direction depending on which side is slipping. the wheel wont keep slipping due to dry conditions and here its just the power is too much for the tire, but your natural response might be to lift off and try and save it like you would on an open diff, but under "DRY conditions" its often preferred to power through it while slightly lifting off the throttle and counter steering to regain traction, that way the wheel without traction can catch up and keep you straight again, cause if you just let off and brake while you don't have trac on the slipping wheel you might just end up a decent amount sideways as well. everyone has their own style though. so lifting off is not always as usefull with an lsd as it was on oyour open diff, I know on my open I can push the throttle down and kick it out a little in the rain, but I would never, and I repeat never try that with an LSD unless I was on purpose trying to drift.
best advice is find a very very open parking lot, and give it a test out. power over the thing until you learn the difference going sideways. loose traction and then lock up the brakes, try out things you might be worried about. on a wet day if you do it you will see how floaty the rear will become on you, I have an open diff in my SC and I don't go more than 35% throtlte in the rain as it literally starts spinning one wheel and the back end will move either to the right for me. With LSD it would move much faster and is harder to catch. I actually haven't bothered to install a LSD yet because it takes more attention to drive the car, Lexus stopped putting LSD standard on newer models because its more dangerous if you don't know how to drive one. they also started making the newer models understeer on purpose but that is a whole different discussion.
LSD is helpfull for performance driving, burnouts, drifting, all that good stuff, but its important to understand whats going on because it inherently makes a rwd potentially more dangerous if you don't know how to drive with one.
Wow! Had to read that multiple times. I almost backed out of the LSD as wet weather handling is a huge concern for me. I am going to proceed with it but keep my open diff just in case. I need to get comfortable with tires breaking loose in the rain. I am going to look into lessons on a track.
Thank you for the serious schooling on LSD. I guess its no surprise you know these as well.
The way I look at it, LSD makes you less likely to slip but more likely to spin. That subtle distinction is why it's such a confusing topic. I've found myself pointing the wrong way in traffic on two occasions when giving it a bit too much throttle turning out from a stop... That'll make you pucker!
thank you for the informative thread. i also recently bought a TT Auto Torsen diff, and
installed it yet. Good thing i read through this, because i'd hate to learn the hard way.
The way I look at it, LSD makes you less likely to slip but more likely to spin. That subtle distinction is why it's such a confusing topic. I've found myself pointing the wrong way in traffic on two occasions when giving it a bit too much throttle turning out from a stop... That'll make you pucker!
Would you prefer open diff in the rain or do you prefer the torsen?
I haven't had the chance to do an A-B comparison, so I'm not really sure. The two times I spun, I was making a soft 90 degree turn from a stop, crossing over a non-level center lane that unsettled the suspension.
The first time, I thought the road was oily after raining or something and wrote it off as a freak occurrence. The second time, I realized there is a proper way to drive with a Torsen! Be cautious with the throttle any time there's a chance of the two drive wheels doing different things, and wait for that reassuring feeling of grip before laying into it more. Rain obviously increases the odds of the tail breaking free, but I've never had a problem since with being more careful in those situations. Of course, I also don't drive the car much in "top up" weather.
If I were pressed for advice, it would probably be to stick with whatever you've already got installed, because a pretty good case could be made for either. Having said that, I've come close to buying a LSD for the SC.
08-06-15, 09:45 PM
Just got an LSD for my build. How will this change my driving experience?
I personally like BFG Comp2's for all-weather (no snow) traction and dry fun. The now discontinued BFG KDW2's are what once scared the daylights out of me in a sudden 360 in the rain with a Torsen in the rain. At 25mph. So avoid anything like that which performance car people review as having "bad rain traction". 
