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if you into racing your car. our cars have a red line of just 6000 so to me you want to be in traps at about 5800. you don't want to shift into 0.D before the traps. you want to be pulling hard.
Ghump,
Thanks for your post and great explanations.
I also intend to swap the diff on my 2002 SC430 for one with a 3.769 ratio, and I have the following questions:
1) Did your speedometer indicate the correct speed after the swap or did you have to re-calibrate?
2) Did you encounter any other problems related to the car's electronics?
I actually had to re-read my post to remember what the heck I wrote. Anyway, your first question is a real good. I haven't actually measured the speedo to confirm, but I don't think it changed the readings. Hopefully, some others who have the done the 3.769 LSD can chime in as I can't say for sure.
No problems as far as check engine lights or codes or anything else. Everything is running smooth as silk.
I did get the Sprintbooster a while back and what a difference that thing makes. The car feels much quicker and shifts down with much less pedal movement. The max setting is wild, but the medium setting is more civilized and just right for normal driving.
I also went into the valve body and changed the adjustable setting for higher pressure for slightly quicker shifts. A little difference, but not much. I'm thinking about trying to shim the actuator springs to get quicker shifts. Not sure when I'll get that done, but I'll post if it is a good mod.
Just found this post regarding changing rear end ratio.
Yea so the speedometer will be inaccurate after changing the diff ratio. The speedometer is based on output shaft RPM so if you increase the gear ratio from 3.27 to 3.76 your output shaft will be spinning more for a given speed than before and thus your speedometer will read higher (proportionally to 3.76 divided by 3.27) by approximately 15%.
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I have tried to research the possibility of re-calibrating the speedo on an SC430 and have come up empty...so far. So the question is, has anyone here successfully solved this issue? One way might be to put different size tires or wheel tire combo to get the speedo more accurate. The question would then be, what size?
I did some more research and most of the info said that the speedo on most later models, including the 2002 SC430 derive the speed from the wheels. I just got back from a drive on the freeway, using a GPS to measure speed and I can tell you my speedo is right on, if fact, it was almost perfectly in sync with the Garmin, usually within 1 or 2 mph. I went from 50 to 75 mph and the results were linear and right on. Bottom line, change your gears with impunity!!
Thanks a bunch for testing - real kind of you!
I was actually hoping hat the speedo signal would come from the ABS (sensor on wheel) and not from the gearbox, but I was unable to confirm. I will proceed with impunity at once.
Yes, it wasn't easy to find much info on the subject. I just happened to come across a discussion. There is a lot of good info I pulled off this site on doing the swap and also there is a series of videos on youtube from a guy who did a swap on a SC300 that I found useful.
I am thoughly enjoying my 2004"SC with the Supra 3.67 LSD. I changed all bushing with Figs bushings at that time. I have a reduction in mpg of about 2-3 mpg. The speedometer is right on taking data from the wheel sensors. However the ecu takes the data from the shaft speed. This causes the ecu to think the car is going a lot faster than it is and hits the speed limiter at about 118 mph. I was able to solve this with a speed limit defeater from HKS although it triggers the VSC/VSC Off light but reaches 147 mph on the dyno before the speed limiter cuts the engine power. There is another product from Apexi but I havent tried it yet. I will use the HKS device next time I'm on the track in March.
Ghump
Following our earlier conversation on this thread, I recently installed a 3.769 lsd from a 95 Aristo into my 2002 SC 430 and it works very well.
The dilemma is that I am now offered a low mileage 2008 SC 430 at a very attractive price and am tempted to trade. But only if I can swap the lsd from the 2002 into the 2008.
From your excellent write-up I understand that the old diff will not fit into the new car due to the difference in axle design. Hence my idea is to replace the differential plus the axles. Based on your research and knowledge, will this work, i.e. are the 2002 axles compatible with the 2008 hubs? Thanks for your advice.
hscholl
I would think that swapping the Diff and replacing the axles would work. I think the splined end that goes into the wheel would be the same. With the design of the newer axles, I have a tough time figuring out how that axle could be removed from the diff. Very tough to get the leverage to knock the axle out while under the car?? With my diff on a work bench, it took quite a rap to knock out those fittings. They are held in there with a compression ring. The good news is that the axles for the 2002 thru 2005 are readily available. While doing the swap I noticed one of the axles had some damage and I replaced it. I found a rebuilt one at a reasonable price. Anyway, the only thing you might want to check out is that the flange of the drive shaft on the 2008 would fit the older diff. I think I read somewhere on this sight that the newer SC's had a drive shaft flange that didn't match up with the older LSD. Unfortunately, the only way to really find out is to try it. When I did mine, I was pretty sure that everything would fit, but you can't be sure until you actually do it. Good luck, if you decide to buy the 2008 and do the swap. I would be interested in hearing how it works out.
Hi. I have a 2003 Lexus SC430 and interested in a compatible LSD!
Hey, I had a couple of questions! I really want to figure out where I can get an LSD that is compatible with my 2003 SC430. So far I know that a 95 supra twin turbo LSD automatic is bolt on for my car. Would you happen to know where I can get one and the exact name and numbers of the part is? The one you wrote about isn't from a supra? Is there a difference in power from the onen u have and the supra one? So far i have a magnaflow catback exhaust..OBX headers... Torque controller..AEM intake..Please help me out..i try to look for it on EBAY but its usually not the one that is compatible with my car...attached I have a photo of my car. Take care!
I can't help you with acquiring a LSD, as I never looked for one. The long and short of this whole project is matching the differential to your existing axles (and sub-assemblies). Because yours is an 03, a 3.769 diff. out of a another Lexus should be a direct bolt on, but I don't know about a Supra LSD...sorry.
01-25-16, 01:01 PM
