3.91 diff installed.

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Aug 12, 2003 | 01:29 PM

#16

ceboyd

Lexus Test Driver

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From: Illinois

but how loud is it on the highway now?

Aug 12, 2003 | 01:32 PM

#17

LexPro

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From: Texas

Dont think it is any louder. Why do you think because of the RPM's?

Aug 12, 2003 | 02:05 PM

#18

DaveGS4

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From: North Carolina

Quote:

Originally posted by LexPro
Now with this redline thing I think that is totally wrong. I dont see how a manufacturer can program a car to shift at certaind MPH during wide open throttle, they are programmed to shift at RPM's. I dont have any issues with redline and my car shifts now at the same RPM (a little over 6000) and different speeds. .

Dan,

I'm glad it sounds like you don't have the issue, but the unfortunately I'm not "totally wrong" about it. Some GS owners have removed and sold the 3.76 gearing they bought and installed in their car because of it. From my understanding it's not the MPH that factors into the equation, it's the speed at which the engine arrives at a particular RPM to shift. I suspect Lexus built some logic into the shifting algorythm that anticipates when the car will reach redline to shift. When it reaches the redline sooner and hasn't shifted yet, it bangs the rev limiter before it can switch gears. Something similar happens for many of our GS members who have added forced induction to their cars. Just my theory; it is a problem for some with the taller gears, but not for others. Don't know why.

Don't get me wrong, I really hope this is an inexpensive mod to make lots of SC430's faster and I'm certainly glad you're trying it

!!! Just want to make sure the first few folks who do it to keep an eye out for this issue as it only happens under wide open throttle. Programming may be different enough on the SC430 that it isn't an issue at all

.

For 0 -60 times, you might be able to find someone local who has a G-Tech or G-Tech Pro device which measures that, your 1/4 mile times, etc.

Last edited by DaveGS4; Aug 12, 2003 at 02:06 PM.

Aug 12, 2003 | 02:22 PM

#19

LexPro

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From: Texas

I was thinking of buying a Gtech soon.

Aug 12, 2003 | 08:21 PM

#20

ceboyd

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From: Illinois

Quote:

Originally posted by LexPro
Dont think it is any louder. Why do you think because of the RPM's?

yes, was wondering if the higher revs transfered badly to the cockpit or not? IE.. I can't stand hearing the high rev's in the S2000 rev happy car!

Aug 13, 2003 | 09:23 AM

#21

LexPro

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From: Texas

CEBOYD, I dont notice any difference.

Sep 3, 2003 | 06:15 AM

#22

dsmith

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Joined: May 2003

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From: Texas

Many other gears will probably work as well. ADP Hollander interchange shows all SC400, SC300, SC430, GS300, GS400, GS430 and 2002 up LS430 are interchangeable. I put a 96 SC300 manual diff, 4.11 gear, in my 92 SC400. Made a big difference in acceleration. Gas mileage went down about 2 mpg. There is a speedometer correction adaptor for the older models. I don't know about the newer ones. Even with the deeper gear, my 92 will not keep up with my 2002 SC430.
The swap took about 2 hours, not real technical, but quite a bit of wrestling and jostling to get everything back in place.