I have a 2002 SC430 which is noticably slow in downshifting. It has been this way since I purchased it used in 2002. I have tried to no avail to get some help from my local dealer,I thought that Lexus might be able to reprogram the ECU to improve the shifting.

Does anyone have any first hand experience on how to upgrade transmission shifting for sportier performance?

Thanks.

 

no they can't reprogram the ecu to improve shifting. the ecu is like that, designed from japan, so...

the problem is the full drive by wire system and the throttle response, which in the case of any 430 engine setup (with 5 speed tranny) are very slow and need getting used to. once you are used to it you can time it and know how hard you have to press on the gas to get yourself going.

coming from gs400 (with much better throttle response), it was a tough time for me to get used to my sc430. but once used to it,i know i have to press harder and the downshift will kick in right the way and my car becomes a rocket

 

Thanks for the feedback. You're right, they do go like a rocket and that puts a big smile on my face. I'm just impatient and want the smile instantly!

 

When you get used to it, if you still find the downshifting slow you should have a look at a torque converter. Im trying to import one home at the moment. The dealer claims seem quite large.. like 40-50 bhp increase and 0.7 seconds off the 0-60 time that and a Blitz exhaust should make one very quick SC

 

torque converter doesnt add HP though

 

I think it does. Henry knows he knows everything

 

nop, it does NOT add any power, sorry. but first of all it's lighter, and also it raises the stall speed, which means allowing the engine to rev high before fully engaging with the tranny.

the stall speed of the stock converter is around 1800rpm, and the stall speed of most common aftermarket coverter (precision industry dragon) is 2800rpm.

although no official real hp added, but your car will be MUCH MUCH faster, and yes the throttle response will be much better as well. i have that on my gs400 together with the supra tt lsd, the result is incredible. my sc430 has no chance against my gs400

btw, just keep in mind, if you put on the tq converter, more than likely you will get the check engine light. there is a sensor on the tranny that will sense that the stall speed is different and flag you

 

My 06 sc 430 is very crisp in shifting. If I want to shift manually so to speak, it is easy to do with the six speed. I think that it is a good set up.

 

the 06 with the 6 speed is totally different, with different tranny AND ecu setup. throttle response is a lot quicker and more responsive. drove the ls430 and it's night and day

 

the 06 tranny is better, but it's still fxxked up. you can manually shift up or down, but after you come to a stop, the tranny will not return to first gear automatically. that means every time you come to a stop the manual tranny falls back to auto mode unless you manually down shift to 1st gear. imagine you are cruising on an express way in 6th gear. once you come to a stop light, you would have to down shift 5 times to return to 1st gear in preparation for launch. if i want to drive in manual mode, why the fxxk do i want the tranny to go back to auto at every stop?! That's major fxxkup.

 

Thanks Henry, how does l-tunedparts get away with saying..

http://www.l-tunedparts.com/product/?id=3

 

It behaves (feels) as if it has the additional HP though it does not add HP.


Yep, TC will help and coupled with a 3.76 rear end will open up the car. I am referring to the PI(dragon) converter which is smaller in diameter and weighs less than the OEM unit which equates to quicker throttle response and quicker acceleration due to the less rotational mass + the higher stall speed to boot. Some have their converter changed to a higher stall but you are not realizing the other benefits of the aftermarket version which are designed from the get go to be a stronger and lighter TC.

Put another way when I had an SRT intake/exhaust on my GS400 (which has better throttle response but not necessarily quicker) I raced another members GS430 who had SRT intake, exhaust, and TC. He crushed me from the line and put 2 cars on me in no time so……so much for throttle lag. Get the TC and smile from every stop light. Do a search here and look at the results. Those that have the TC are always upset they did not do it sooner. TC alone will take from 3.-.5 off your 0-60 times and .3 off your 1/4. Howz dat! Though you may not be interested in quicker acceleration times, the drivability benefits are there. I’m currently running a 5.67 0-60 and ¼ in 14.21 at 101.9mph and the TC/LSD should take the car straight to 5 flat and 13's.

Another option which is on my list of things to do is to check the throttle sensor at the pedal and TPS (Throttle Position Sensor) for tweaking. Many older GS400's also had severe throttle problems and kick down issues. Lexus issued an updated ECU to fix that. My GS400 was good but I tweaked the TPS setting a tad from the recommended factory setting and the throttle response was noticeably better and the engine idled smoother which is another huge issue with GS400 owners.
Lee,

 

well...... i hate to say, but before you start going off and bad mouthing lexus, go read your dearest user manual first and understand how things work.... the number on the dash shows the "highest gear the car can be in", it does NOT mean "the gear that the car is in" for god's sake. and why don't you do an experiment for yourself. go at highway at 6, and then come to a stoplight. then when green, FLOOR the car and see

1) if you get upshifts. my bet is you will get 5 shifts if you have that much road ahead of you
2) if your car is just as fast. i bet it is coz' the car still starts from the darn first gear

the way sport shift works is for you to determine the highest gear it is in. so if you start in 1, that means the car can only stay in 1, it will bounced at the limiter if you don't upshift. then if you shift to 2, it will shift into 2 immediately, and then bounce off the limiter when it hits redline. same for 3, 4, 5, and 6. HOWEVER, it does NOT say anywhere that it's stay in that PARTICULAR gear. meaning even if you are at 3, and then you come to a stop. the car will automatically start in 1st gear again when you start rolling.....

a lot of people misunderstand how it works, but geeez they gave us the user manual for a reason

also, you have s2000 before with real 6 speed manual, so i am sure you know manual well. start the car in 6th gear (assume you don't care about completely burning your clutch, and that you can actually get the car to roll without stalling it), the car is freaking slow right? keep the sc430 in "6" and start to roll the car, the car isn't slow, just normal. so it can't be 6th gear

well, i think they should definitely correct their saying. equivalently (in terms of 0-60 times, etc...) it's probably right to say it gains that much power, but being real car enthusiast and one that want to know the real reason, we have to be careful on the exact cause behind.

for example, my friend (gs400) with tq converter and supra tt lsd? on the dyno it shows almost no difference (pretty much the same numbers), but the car is substantially faster than any gs400 you can pick out there

 

Thanks Henry , that clears that up. Guess they should really change the wording to feels like 40-50 hp increase

What kinda LSD would you fit on an SC, Supra one?

Lee thanks for your help on the headers.. they still havent got back to me. Does anyone know for sure if the SS headers will fit a right hand drive SC?

 

no problem. i really don't blame carson for saying that, in 2 sentences that's probably the easiest way to present the power improvement of the tq converter. but technically i am not sure if that's entirely correct.

the supra tt lsd rear pumpkin with 3.76 gearing will fit on the sc430 no problem. same as the gs400 (that i have). the stock one is 3.26 gearing, so you gain quite a bit by going to 3.76. careful when you floor after putting in the new rear end, the car can go pretty damn wild.

on my gs400 i can easily burn through the whole 1st gear if i am mad, and that's on not necessarily light weight 20s with 285 tires