3.91 diff installed.
08-12-03, 02:05 PM
#18
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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. .
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. .
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; 08-12-03 at 02:06 PM.
08-12-03, 08:21 PM
#20
Lexus Test Driver
Originally posted by LexPro
Dont think it is any louder. Why do you think because of the RPM's?
Dont think it is any louder. Why do you think because of the RPM's?
09-03-03, 06:15 AM
#22
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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.
The swap took about 2 hours, not real technical, but quite a bit of wrestling and jostling to get everything back in place.
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