ISF with IS350 Diff...
Lexus Champion
Joined: Jun 2007
Posts: 2,148
Likes: 0
From: Aventura, Florida
Ok so i got my is350 diff installed today and the acceleration increase from 0-120 is very noticeable but the car is done...(not out of gear) but just falls on its face about half way threw 7th gear at 130-135. It feels like the computer pulls timing or something. The power is just gone.
First gear is a complete smoke show, the car picks up traction yet is still spinning threw second, third locks up and your gone. Then your at that 130mph wall before you can get over acceleration. If you don't care about top end, gas isn't your top priority and you haven't done this mod im not sure whats wrong with you. It brings the term HOT ROD to the ISF.
My buddy took some video il put up later with and without a 100 shot No2 on with the is350 diff installed
5-100mph in 9-10sec on street tires
First gear is a complete smoke show, the car picks up traction yet is still spinning threw second, third locks up and your gone. Then your at that 130mph wall before you can get over acceleration. If you don't care about top end, gas isn't your top priority and you haven't done this mod im not sure whats wrong with you. It brings the term HOT ROD to the ISF.
My buddy took some video il put up later with and without a 100 shot No2 on with the is350 diff installed
5-100mph in 9-10sec on street tires
Driver
Joined: May 2011
Posts: 128
Likes: 1
From: Nevada
Interesting- I wonder if there is something coded for fuel efficiency in 7th and 8th gears. If you do the math out, there shouldn't be that much of a difference between the overall ratio in 5th gear with the OEM diff (3.61:1) vs 7th with the IS350 diff (3.37:1) .
I have an IS350 diff on the way and I'll report back once I get it installed as well.
I have an IS350 diff on the way and I'll report back once I get it installed as well.
Given that it uses the same pinion bearing, I should be able to swap the gears from a 2SC into either an IS350 case or an ISF case, though?
http://www.lexussouthatlantaparts.co...tial%20carrier
http://www.lexussouthatlantaparts.co...tial%20carrier
http://www.lexussouthatlantaparts.co...tial%20carrier
http://www.lexussouthatlantaparts.co...tial%20carrier
Ok so i got my is350 diff installed today and the acceleration increase from 0-120 is very noticeable but the car is done...(not out of gear) but just falls on its face about half way threw 7th gear at 130-135. It feels like the computer pulls timing or something. The power is just gone.
First gear is a complete smoke show, the car picks up traction yet is still spinning threw second, third locks up and your gone. Then your at that 130mph wall before you can get over acceleration. If you don't care about top end, gas isn't your top priority and you haven't done this mod im not sure whats wrong with you. It brings the term HOT ROD to the ISF.
My buddy took some video il put up later with and without a 100 shot No2 on with the is350 diff installed 5-100mph in 9-10sec on street tires
First gear is a complete smoke show, the car picks up traction yet is still spinning threw second, third locks up and your gone. Then your at that 130mph wall before you can get over acceleration. If you don't care about top end, gas isn't your top priority and you haven't done this mod im not sure whats wrong with you. It brings the term HOT ROD to the ISF.
My buddy took some video il put up later with and without a 100 shot No2 on with the is350 diff installed
5-100mph in 9-10sec on street tiresnice!!! i did notice that too when i hit 7th or 8th gear the car feel like it doesnt pull anymore.
Here are some videos from the testing of the IS350 rear differential in my ISF
4.09 wIth 100 shot, coming on in 3rd gear via nitrous controller
http://youtu.be/iIB2nkLmUzQ
N/A pulls with 4.09
http://youtu.be/FF2eCJsbqwU
This is 6ish minute but goes threw me realizing the car will cut out at about 130mph with the 4.09 in 7th gear. you can hear the car die down from the computer and its just done.... Its really weird and quite obnoxious.
http://youtu.be/FX9xKthC8TU
4.09 wIth 100 shot, coming on in 3rd gear via nitrous controller
http://youtu.be/iIB2nkLmUzQ
N/A pulls with 4.09
http://youtu.be/FF2eCJsbqwU
This is 6ish minute but goes threw me realizing the car will cut out at about 130mph with the 4.09 in 7th gear. you can hear the car die down from the computer and its just done.... Its really weird and quite obnoxious.
http://youtu.be/FX9xKthC8TU
Interesting- I wonder if there is something coded for fuel efficiency in 7th and 8th gears. If you do the math out, there shouldn't be that much of a difference between the overall ratio in 5th gear with the OEM diff (3.61:1) vs 7th with the IS350 diff (3.37:1) .
I have an IS350 diff on the way and I'll report back once I get it installed as well.
I have an IS350 diff on the way and I'll report back once I get it installed as well.
Driver
Joined: May 2011
Posts: 128
Likes: 1
From: Nevada
If 7th gear does have a fuel efficiency hard code the GS 430 3.7 rear end is the way to go. First would be a little more livable, car would still do 150mph and 8th would be a little better for for highway cruising. I like auto more with the up'ed final drive. When you give the car gas it doesn't have to down shift as much to get not the power. Car should have like a 3.5 rear gear from the factory, would be perfect.
https://www.clublexus.com/forums/is-...top-speed.html
180 mph would be around 5500 RPM in 7th gear, which is right where 130 mph is with the 4.09. I guess they must have coded the ECU to cut at a certain RPM/gear combo as opposed to speed.
It looks like HKS makes a speed limiter removal tool for the Japanese market, but it's like $1,500.
Driver
Joined: May 2011
Posts: 128
Likes: 1
From: Nevada
Driver
Joined: Aug 2012
Posts: 50
Likes: 4
From: VA
If it is the speed limiter, I think that Sard and Toms make something as well. From memory though, both of those and the HKS unit ran ~ $2,000.
Pole Position
Joined: Sep 2012
Posts: 244
Likes: 5
From: Greenville, SC
I take my original guess back- I think you are hitting the hard speed limiter:
https://www.clublexus.com/forums/is-...top-speed.html
180 mph would be around 5500 RPM in 7th gear, which is right where 130 mph is with the 4.09. I guess they must have coded the ECU to cut at a certain RPM/gear combo as opposed to speed.
It looks like HKS makes a speed limiter removal tool for the Japanese market, but it's like $1,500.
https://www.clublexus.com/forums/is-...top-speed.html
180 mph would be around 5500 RPM in 7th gear, which is right where 130 mph is with the 4.09. I guess they must have coded the ECU to cut at a certain RPM/gear combo as opposed to speed.
It looks like HKS makes a speed limiter removal tool for the Japanese market, but it's like $1,500.
Darbs - thanks for the vids. Can't wait to see how it impacts your 1/4 mile times. When will you run again?
As i was reading through this and watching the videos and was thinking the same thing! Thanks for the spreadsheet confirming the 7th gear rpms. I was just getting ready to put one together
Darbs - thanks for the vids. Can't wait to see how it impacts your 1/4 mile times. When will you run again?
Darbs - thanks for the vids. Can't wait to see how it impacts your 1/4 mile times. When will you run again?
Last edited by darbs242; Sep 10, 2012 at 07:23 PM.
Lexus Champion
Joined: Jun 2007
Posts: 2,148
Likes: 0
From: Aventura, Florida
Il be at the track on Saturday with MS109, 150 shot, the new nitrous controller & obviously the diff. I think im going to shift around 6,5oo rpm because with the 4.09 the transmission only drops 900-1500 rpm when you shift and that will keep me in the peak of the power. Should make between 550-575 hp and 575-600tq at the wheels once the juice kicks in. I have it set to spray in 3rd and up at WOT between 3000-6400 rpm... il probably run my slicks around 11 psi. Wish me luck