i found this interesting (some lsd info)
07-27-04, 10:36 PM
#1
Lexus Fanatic
Thread Starter
i found this interesting (some lsd info)
http://www.mkiv.co.nz/techo.htm#TORSEN_VS_TRD_DIFF
Torsen LSD vs TRD LSD
The Torsen diff is a standard fitment to all 6 speed mkiv's, alot of the Auto TT's and you'll even occasionally find it on a NA. You can tell if your Supra has a Torsen diff by reading the Trans/Axle code on the Engine Tag which is situated under your bonnet. The last letter of the 4 character code (eg. B03B) denotes the diff type which is "A" for a std diff and "B" for a Torsen diff.
The Torsen (TORque SENsing) LSD (Limited Slip Diff) works quite differently to the TRD LSD. The Torsen is a Torque Multipling type of diff with a multiplication ratio of around 5:1. What this means is that whatever torque can be sent to the wheel with the least traction, it can send up to 5 times that torque to the wheel with the most traction. Its biggest advantage is that it can do this extremely quickly and doesn't ever lockup the ratio, but is continuously "sensing" and adjusting the torque between the two wheels. Its only real disadvantage is that when one wheel has no torque available (say it spinning in mud), then 5 times nothing is still no torque to the other wheel, so you can get stuck just like a std diff. Once the car is moving however this cannot happen. See this Torsen Differential Article for a detailed explanation of how the Torsen diff works.
The TRD LSD is a standard type LSD in that it uses clutch packs to transfer torque from one wheel to the other. Transferring torque via clutch packs will be a slower process then the Torsen transfer method and it will absorb more energy from the engine when doing so. However we are probably only talking a few hundreds of a second difference here and maybe a few hp. The main disadvantage of the TRD diff is that it can "lockup" the ratio between the two wheels at 1:1. This means both wheels will then turn at the same speed and if this happens on a corner, it would be exciting at the very least. This "lockup" is also its only advantage over the Torsen diff as even when one wheel is in the mud, the other wheel can provide traction to pull you out.
My personal preference is for the Torsen diff as it usually comes free with the car, reacts quicker and aborbs less power and will never accidentally lockup. However, if you want to go rally driving in your mkiv Supra (don't laugh, there's guys in the USA that do just that) then the TRD would be the better bet.
Traction control - good or bad?
On several occasions, I (Kevin) have found the traction control on my TT to be EXTREMELY DANGEROUS. This is because it is too good. When it activates, due to rear wheel spin, it dials the power back far too much, leaving you with no more then idle hp. In the wet, or on gravel, it is easy to spin the rear wheels when starting off, and several times I have almost been hit by another car when pulling out to cross a road and having the traction control suddenly kick in. I now always turn the traction control off, when it starts raining or I'm on gravel, to prevent this happening. I will be removing the traction control entirely, hopefully at the same time I do my intercooler upgrade.
But won't this make your TT more dangerous by not having any traction control?
I have raced my car in both the dry and the wet (always with the traction control turned off) and because the LSD requires both rear wheels to spin, it is quite difficult to promote rear end breakaway, but obviously possible, if you overdo it. Personally, I think that as long as you drive to suit the conditions, then it is safer to not have traction control, due to the above mentioned risks when pulling out into traffic on wet or gravel roads. If anyone else has had similar situations with the traction control, then (let me know) so other readers can be that much more aware of the dangers of traction control.
My experience (Joe) with it has overall been bad. I have it almost permanently turned off (fuse supplying power to the traction control ECU pulled in the main fuse box in the engine bay) now. What I found was that when you had a small lose, it worked okay. But, when you had a big lose, it cut in way too late to save you, and when it did cut in was when you’d be trying to power-out of the situation – ie when you least expected it, or wanted it to !! Worse still, after you’ve recovered from the situation & regained traction, it continues to cut power for quite some time – bloody annoying.
You can also totally remove the butterfly valve used to activate the traction control (there is a kit you can buy to fill the holes left or you could just get them welded up). This also has the advantage of removing an unnecessary air restriction in the inlet manifold. This butterfly valve is the front one on the inlet manifold. The rear one is the throttle control butterfly.
*************************************************************************************************
probably already been covered so if it has this can be deleted
oopps can you move to engine section sorry
Torsen LSD vs TRD LSD
The Torsen diff is a standard fitment to all 6 speed mkiv's, alot of the Auto TT's and you'll even occasionally find it on a NA. You can tell if your Supra has a Torsen diff by reading the Trans/Axle code on the Engine Tag which is situated under your bonnet. The last letter of the 4 character code (eg. B03B) denotes the diff type which is "A" for a std diff and "B" for a Torsen diff.
The Torsen (TORque SENsing) LSD (Limited Slip Diff) works quite differently to the TRD LSD. The Torsen is a Torque Multipling type of diff with a multiplication ratio of around 5:1. What this means is that whatever torque can be sent to the wheel with the least traction, it can send up to 5 times that torque to the wheel with the most traction. Its biggest advantage is that it can do this extremely quickly and doesn't ever lockup the ratio, but is continuously "sensing" and adjusting the torque between the two wheels. Its only real disadvantage is that when one wheel has no torque available (say it spinning in mud), then 5 times nothing is still no torque to the other wheel, so you can get stuck just like a std diff. Once the car is moving however this cannot happen. See this Torsen Differential Article for a detailed explanation of how the Torsen diff works.
The TRD LSD is a standard type LSD in that it uses clutch packs to transfer torque from one wheel to the other. Transferring torque via clutch packs will be a slower process then the Torsen transfer method and it will absorb more energy from the engine when doing so. However we are probably only talking a few hundreds of a second difference here and maybe a few hp. The main disadvantage of the TRD diff is that it can "lockup" the ratio between the two wheels at 1:1. This means both wheels will then turn at the same speed and if this happens on a corner, it would be exciting at the very least. This "lockup" is also its only advantage over the Torsen diff as even when one wheel is in the mud, the other wheel can provide traction to pull you out.
My personal preference is for the Torsen diff as it usually comes free with the car, reacts quicker and aborbs less power and will never accidentally lockup. However, if you want to go rally driving in your mkiv Supra (don't laugh, there's guys in the USA that do just that) then the TRD would be the better bet.
Traction control - good or bad?
On several occasions, I (Kevin) have found the traction control on my TT to be EXTREMELY DANGEROUS. This is because it is too good. When it activates, due to rear wheel spin, it dials the power back far too much, leaving you with no more then idle hp. In the wet, or on gravel, it is easy to spin the rear wheels when starting off, and several times I have almost been hit by another car when pulling out to cross a road and having the traction control suddenly kick in. I now always turn the traction control off, when it starts raining or I'm on gravel, to prevent this happening. I will be removing the traction control entirely, hopefully at the same time I do my intercooler upgrade.
But won't this make your TT more dangerous by not having any traction control?
I have raced my car in both the dry and the wet (always with the traction control turned off) and because the LSD requires both rear wheels to spin, it is quite difficult to promote rear end breakaway, but obviously possible, if you overdo it. Personally, I think that as long as you drive to suit the conditions, then it is safer to not have traction control, due to the above mentioned risks when pulling out into traffic on wet or gravel roads. If anyone else has had similar situations with the traction control, then (let me know) so other readers can be that much more aware of the dangers of traction control.
My experience (Joe) with it has overall been bad. I have it almost permanently turned off (fuse supplying power to the traction control ECU pulled in the main fuse box in the engine bay) now. What I found was that when you had a small lose, it worked okay. But, when you had a big lose, it cut in way too late to save you, and when it did cut in was when you’d be trying to power-out of the situation – ie when you least expected it, or wanted it to !! Worse still, after you’ve recovered from the situation & regained traction, it continues to cut power for quite some time – bloody annoying.
You can also totally remove the butterfly valve used to activate the traction control (there is a kit you can buy to fill the holes left or you could just get them welded up). This also has the advantage of removing an unnecessary air restriction in the inlet manifold. This butterfly valve is the front one on the inlet manifold. The rear one is the throttle control butterfly.
*************************************************************************************************
probably already been covered so if it has this can be deleted
oopps can you move to engine section sorry
Last edited by T.L.W.; 07-27-04 at 10:38 PM.
07-27-04, 11:59 PM
#2
very good read. those guys over there definitely know their stuff. i would add a bit more info, maybe we can have a little sticky or faq about this.
the disadvantage of the torsen lsd, yes, is that if one wheel has no traction, the other wheel still has nothing. but a very simple and easy way to fix this problem is to slightly apply brakes. this will create a force on the rear wheels, aka the one that has no traction. it will create some friction (traction) and it will transfer the tq to the other wheels.
one application is when you go up a very steep driveway at a steep angle on the right. specially if your car is lowered with coils, i pretty much guarantee that if you go slow, the rear right wheel will be hanging in the middle of nowhere and your car wont' go up or down at all. if you have the torsen, just slightly pretty on the brakes and the lsd will push power on the left rear wheel for ya.
on the other than, the clutch type lsd (trd), from what i heard, will be able to hold more power than the torsen type. if that's the case, if you have fi, maybe it's a better option (aside from the gear ratio).
about the traction control, i think i will add that with the lsd yes indeed it will help a bit on the driving coz' both wheels will be biting now. however, with the power on the gs (specially gs4), ONLY turn off the vsc if you know what you are doing. if you forget for one moment that it's off and you press the gas hard even on a turn, have fun.... trust me on this one....
the disadvantage of the torsen lsd, yes, is that if one wheel has no traction, the other wheel still has nothing. but a very simple and easy way to fix this problem is to slightly apply brakes. this will create a force on the rear wheels, aka the one that has no traction. it will create some friction (traction) and it will transfer the tq to the other wheels.
one application is when you go up a very steep driveway at a steep angle on the right. specially if your car is lowered with coils, i pretty much guarantee that if you go slow, the rear right wheel will be hanging in the middle of nowhere and your car wont' go up or down at all. if you have the torsen, just slightly pretty on the brakes and the lsd will push power on the left rear wheel for ya.
on the other than, the clutch type lsd (trd), from what i heard, will be able to hold more power than the torsen type. if that's the case, if you have fi, maybe it's a better option (aside from the gear ratio).
about the traction control, i think i will add that with the lsd yes indeed it will help a bit on the driving coz' both wheels will be biting now. however, with the power on the gs (specially gs4), ONLY turn off the vsc if you know what you are doing. if you forget for one moment that it's off and you press the gas hard even on a turn, have fun.... trust me on this one....
07-28-04, 07:53 AM
#3
EV ftw!!!
Excellent info guys!!! 
This is one of the numerous reasons why a lot of us love CL!!
This is one of the numerous reasons why a lot of us love CL!!
07-28-04, 08:23 AM
#4
Forum Administrator
iTrader: (2)
Nice info Johnny
Here are some excellent threads on limited slip differentials & torsen vs clutch on CL as well. The decision on the GS is a bit different as the torsen limited slip diff almost always comes from a Supra and includes taller gears (3.76) and is an entire pumpkin replacement. The TRD LSD (and the ATS carbon one) is a clutch type that uses the stock gears.
https://www.clublexus.com/forums/sho...h&pagenumber=2
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
Here are some excellent threads on limited slip differentials & torsen vs clutch on CL as well. The decision on the GS is a bit different as the torsen limited slip diff almost always comes from a Supra and includes taller gears (3.76) and is an entire pumpkin replacement. The TRD LSD (and the ATS carbon one) is a clutch type that uses the stock gears.
https://www.clublexus.com/forums/sho...h&pagenumber=2
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
https://www.clublexus.com/forums/sho...=torsen+clutch
07-28-04, 10:22 AM
#5
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Good info...
Thanks for the links. True enough about the Torsen "trick" of applying slight brake pressure. Ask any Humvee owners (NOT the H2) about this phenomenon-they have Torsen diffs too! Works great!
One small note Dave- "taller" gears refers to higher gearing than stock, not lower. In other words, for the GS4-taller gears would be 3.10 to one etc.
Interesting comments on the benefits vs. hazards of traction control too.
One small note Dave- "taller" gears refers to higher gearing than stock, not lower. In other words, for the GS4-taller gears would be 3.10 to one etc.
Interesting comments on the benefits vs. hazards of traction control too.
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