Lexamatic

bg, also consider a torque converter upgrade. I'm thinking it will help with ET & maybe trap speeds. http://www.lextreme.com/tc.htm

slowdiver

iTrader: (10)

I highly recommend the 4.27 gears and PI TC with a large wheel.

Gear ratios expanded with Supra axle codes and Pros/Cons of Clutch-Type LSDs vs Torsen:

Lexus:

95-97 LS400 has a 3.62 gear ratio.

98+ LS400s have a 3.26 ratio.

92-97 SC300
6 cyl, AT (4.27 ratio)
6 cyl, MT (4.08 ratio)

98-00 SC300
6 cyl, AT (4.27 ratio)

92-96 SC400
8 cyl (3.92 ratio)

97-00 SC400
8 cyl (3.266 ratio)

92-96 MKIV Supra

w/o turbo; (4.27 ratio) Limited Slip
w/o turbo; (4.27 ratio)
w/turbo, MT (3.133 ratio) Limited Slip
w/turbo, AT (3.769 ratio) Limited Slip

97-98 MKIV Supra
w/o turbo; (4.08 ratio) Limited Slip
w/o turbo; (4.08 ratio)
w/turbo, MT (3.133 ratio) Limited Slip
w/turbo, AT (3.769 ratio)
w/turbo, AT (3.769 ratio) Limited Slip

Supra Axle Codes denote gearset family, diff ratio and open or LSD centre.

A01A - 3.916 ratio Open Centre
A01B - 3.916 ratio Torsen LSD
A02A - 4.083 ratio Open Centre
A02B - 4.083 ratio Torsen LSD

bg_281

Yea after doing a search on yahoo i'm pretty much sold on the 4.27 with the pi tc... one of my buddies told me he was out at a junk yard and he saw a wrecked SC but he dosen't know if its the 1uz or the 2jz... But i'm gonna check tommorrow... But I'm still confused... forgive me but I am not really familiar with differentials... Now if I get the 4.27 out of an sc300 does it come with lsd? And what exactly is LSD, do I need it, and if so what all do I need to get it done on my GS??? I cant wait to go back to the track and hopefully keep up with them dam domestics off the line... oh and these are the wheels i'm thinking about buying... http://cgi.ebay.com/ebaymotors/20-MR...7321QQtcZphoto

Rock-a-Lex

iTrader: (4)

Keep in mind...you have a GS4XX which utilizes an open 3.23 differential for it's stock rear. Moving up to a Limited Slip differential (LSD) is great because now you will be powering down BOTH wheels for better traction as opposed to mostly one! However, increasing the gear ratio from 3.23 to 4.27 is a SERIOUS jump! Yeah, you will get MUCH better performance (acceleration) but you will be burning a tremendous amount of fuel! For example, I have a GS400 and went from the stock 3.23 gearing to a 3.76 LSD; before I was at 2500 rpms @80mph now I am at 3000rpms @ 80mph. With the 4.27 gears expect to be around 3500 rpms @ 80mph and top speed will most likely drop to around 120mph from the stock (electronically limited) 147mph. You will be running roughly 1000 rpms more at any given speed with the 4.27 gears compared to now! A lot of people go with the 3.76 LSD (so it doesn't KILL the MPG) and get a more agressive stall on their torque converter (for better launches) such as a 3200rpm stall. Hope this clarifies some things for you. Anyone here will tell you that there are ALWAYS trade-off to achieve better performance...always!!!

bg_281

thanks Rock that helped clear up alot of questions that I had... Now as far as the speed governor has anyone heard of a HKS Speed Limit Defencer... http://www.hksusa.com/products/?id=781 I wonder if this will really work??

slowdiver

iTrader: (10)

See page 4 on the link below for LSD research.

https://www.clublexus.com/forums/sho...ight=slowdiver

Rock-a-Lex

iTrader: (4)

Anything that would remove the electronically controlled speed limiter will NOT help you if you are putting steeper gears in your car! You will hit red line in O/D before the computer has to electronically limit you! Like I said before your top speed with 4.27 gearing might be around 120 - 125mph. The stock 3.23 gearing is capable of surpassing the electronically limited top speed of 147mph; then this device will definitely help.

Either that or throw in a 6mt swap to get an extra gear out of the GS...then add that 4.27 rear and you will have the best of both worlds! Fast and hard launch and high top speed w/o the substantial mpg loss!

speedaddic

iTrader: (10)

man...I really want a 3.76 lsd now. Are most of you guys buying new or used? Carson the best place?