Next year's IS-F?
08-08-09, 09:34 AM
#106
OK, let's make it simple: you're wrong. VDIM NEVER turns off completely no matter what you do with the buttons - see below for what the switches do.
As for what I'm getting at - there's a whole lot of chassis set up that determines how much your inside wheel will spin. IME, the F set up isn't problematic until you are trying to squeeze out the last tiny bit of performance, and the car doesn't have an inside wheel lift issue - see below:
It also does not wear the rear brakes heavily (a dead giveaway the electronic LSD is working hard). However, if it does lift the electronic LSD would help by doing what the Torsen can't because the Torsen is multiplying by zero. I'm far LESS concerned the Torsen will interfere with the electronic and a lot MORE concerned the electronic will interfere with the Torsen simply because I'd rather have torque transfer than braking any day.
You said you don't understand how the rear wheels steer the car. It would seem you've not done much work with chassis set up. Rear wheels affect turning pretty dramatically - in karting, the inside wheel is intentionally raised off the surface because they run solid axles and if the inside rear wheel is on the ground, the kart will go straight under power. You really want the outside wheel to have more drive and in a car with independent rear suspension, you'll add toe in to the rear wheels to help the car turn under power. I've done a bit of work on both dirt and asphalt chassis to make cars go faster. There's a lot to it that isn't intuitive or obvious.
As for what I'm getting at - there's a whole lot of chassis set up that determines how much your inside wheel will spin. IME, the F set up isn't problematic until you are trying to squeeze out the last tiny bit of performance, and the car doesn't have an inside wheel lift issue - see below:
It also does not wear the rear brakes heavily (a dead giveaway the electronic LSD is working hard). However, if it does lift the electronic LSD would help by doing what the Torsen can't because the Torsen is multiplying by zero. I'm far LESS concerned the Torsen will interfere with the electronic and a lot MORE concerned the electronic will interfere with the Torsen simply because I'd rather have torque transfer than braking any day.
You said you don't understand how the rear wheels steer the car. It would seem you've not done much work with chassis set up. Rear wheels affect turning pretty dramatically - in karting, the inside wheel is intentionally raised off the surface because they run solid axles and if the inside rear wheel is on the ground, the kart will go straight under power. You really want the outside wheel to have more drive and in a car with independent rear suspension, you'll add toe in to the rear wheels to help the car turn under power. I've done a bit of work on both dirt and asphalt chassis to make cars go faster. There's a lot to it that isn't intuitive or obvious.
http://www.youtube.com/watch?v=vYzXA...eature=channel
Also, my Cayman is mid engined with more weight over the rear axle and I did get wheel spin with my open diff. Now you're telling that the IS-F whose engine is in front on the front axle (much less weight over the rear) with 373lb torque will NOT have issues with wheel spin when applying throttle through a turn?? At the track you are either full throttle or brakes, there is no coasting. If you are accelerating through an apex the weight will shift from the inside wheel of the car to outside thus reducing your contact patch on the inner tire. This WILL result in wheelspin if you do not have either a true mechanical LSD or TBD. You speak of karting and auto-xing. That is not tracking. Only at the track in high speed turns will you notice the need for an LSD/TBD. If you think the oem "electronic lsd" is sufficient you are not a true track enthusiast. True track nuts know that mechanical LSDs/TBDs are far superior to electronic ones. For those individuals who only drive on the street or do not drive at least 8/10ths at the track need not worry about a TBD/LSD as you will never notice a difference. For those who do track aggressively, you will know immediately that a car with over 400 hp and 300 tq is in dire need of true LSD/TBD for ultimate driving enjoyment. In the end we will just have to wait and see if there are any issues with adding a TBD to the IS-F.
-Kevin
Last edited by teoh2005; 08-08-09 at 10:29 AM.
08-08-09, 10:54 AM
#109
Pole Position
Though the VSC in my GS400 is old school compared to VDIM I'm just hoping that the IS-F will respond similarly to a Torsen diff. In the GS with VSC off the limits were raised enough to allow the diff to react before the electronics did. Since the IS-F LSD will react more progressively than a clutch-type LSD I'm hoping it will also react prior to the "electronic LSD" preventing it from turning on until there really is no traction on one side.
Unless I am seriously missing something about the IS-F brake activated LSD wouldn't that imply that it isn't working very hard at all? If the electronic LSD were kicking in wouldn't the rear brakes be used more to slow the wheel with wants to be spinning thus causing more wear? You should be able to see a difference between the amount of pad left on the "inside" or "outside" of the track you were on (depending on the number of right/left turns).
08-08-09, 11:00 AM
#110
Tech Info Resource
iTrader: (2)
Though the VSC in my GS400 is old school compared to VDIM I'm just hoping that the IS-F will respond similarly to a Torsen diff. In the GS with VSC off the limits were raised enough to allow the diff to react before the electronics did. Since the IS-F LSD will react more progressively than a clutch-type LSD I'm hoping it will also react prior to the "electronic LSD" preventing it from turning on until there really is no traction on one side.
Unless I am seriously missing something about the IS-F brake activated LSD wouldn't that imply that it isn't working very hard at all? If the electronic LSD were kicking in wouldn't the rear brakes be used more to slow the wheel with wants to be spinning thus causing more wear? You should be able to see a difference between the amount of pad left on the "inside" or "outside" of the track you were on (depending on the number of right/left turns).
Unless I am seriously missing something about the IS-F brake activated LSD wouldn't that imply that it isn't working very hard at all? If the electronic LSD were kicking in wouldn't the rear brakes be used more to slow the wheel with wants to be spinning thus causing more wear? You should be able to see a difference between the amount of pad left on the "inside" or "outside" of the track you were on (depending on the number of right/left turns).I'm hoping for exactly the same thing you got in your GS since it won't be possible to easily transplant the new skid control ECU in an 08-09 model. In our cars, the skid control ECU is under the HVAC blower motor inside the cabin. They've moved it under the hood near the master cylinder. Damn progress!
08-08-09, 01:09 PM
#111
Hi Kevin,
You guys are making this a Great read!!
Quick pointer, if you press the Trac button once quickly, the "Traction Control" System remains off till approx 20-25mph. Then it turns back ON.
Now if you press and hold the Trac button for 3 seconds, the TRAC & VSC Systems are turned & remain OFF, until turned back ON via button or engine shut down/restart..
"Pedal Dance" is the long way of tunring OFF the trac & vsc system. Which is how it can only be done on some of the 2006 Lexus models.
Regards,
Joe Z
More Visual Aid, turn off at your own risk....
You guys are making this a Great read!!
Quick pointer, if you press the Trac button once quickly, the "Traction Control" System remains off till approx 20-25mph. Then it turns back ON.
Now if you press and hold the Trac button for 3 seconds, the TRAC & VSC Systems are turned & remain OFF, until turned back ON via button or engine shut down/restart..
"Pedal Dance" is the long way of tunring OFF the trac & vsc system. Which is how it can only be done on some of the 2006 Lexus models.
Regards,
Joe Z
More Visual Aid, turn off at your own risk....
-Kevin
08-09-09, 07:32 PM
#112
^^^^Hey guys, this has been a good read, but can we stay on topic? You know, new stuff for the 2010 model.......
Is the A/T temp gauge (the 7 bar light gauge in the middle of the cluster) being replaced with a message of "warning, high a/t temp" or something like that? Did I read the bulletin wrong?
Is the A/T temp gauge (the 7 bar light gauge in the middle of the cluster) being replaced with a message of "warning, high a/t temp" or something like that? Did I read the bulletin wrong?
08-09-09, 09:45 PM
#113
Tech Info Resource
iTrader: (2)
^^^^Hey guys, this has been a good read, but can we stay on topic? You know, new stuff for the 2010 model.......
Is the A/T temp gauge (the 7 bar light gauge in the middle of the cluster) being replaced with a message of "warning, high a/t temp" or something like that? Did I read the bulletin wrong?
Is the A/T temp gauge (the 7 bar light gauge in the middle of the cluster) being replaced with a message of "warning, high a/t temp" or something like that? Did I read the bulletin wrong?
08-10-09, 01:02 AM
#114
things i'd like to see in the 2010 is f:
1) handbrake as opposed to the footbrake
2) three seat bench for rear seating
3) more user-friendly Nav. system
4) LED lights standard for vanity purposes (front and rear)
1) handbrake as opposed to the footbrake
2) three seat bench for rear seating
3) more user-friendly Nav. system
4) LED lights standard for vanity purposes (front and rear)
08-10-09, 06:52 AM
#117
Advanced
08-10-09, 08:50 AM
#119
It's conventional wisdom that cars of this nature benefit greatly from an LSD but Lexus said "We don't need one, we have VDIM", and they now seem to be eating their words. Better late than never I guess.
08-10-09, 10:20 AM
#120
Lead Lap
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Kind of surprised Lexus isn't added the turn signals into the mirrors like they have on the rest of the line-up.
I wonder if they will be on the US cars since the Japanese cars use indicators on the fender.
I wonder if they will be on the US cars since the Japanese cars use indicators on the fender.