Speedometer accuracy and LSD
09-05-07, 06:00 PM
#1
Speedometer accuracy and LSD
i just purchased a supra 3.76 Auto LSD Pumpkin and will be installing it in my sc300 auto. i need to know when can i do to correct for the difference in speed taht will show on the tach? i know it will read about 8 miles an hour more then what it really is. is there any collibration you can do or anything at all?
09-05-07, 06:02 PM
#2
Keeper of the light
iTrader: (17)
On the 97 it is even twice as difficult since it is controlled through the ODBII system. It has to be done digitally.
......or just lean your head to the right a little while driving.
......or just lean your head to the right a little while driving.
Last edited by O. L. T.; 09-05-07 at 06:05 PM.
09-05-07, 06:32 PM
#4
Lead Lap
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Calculator..... Sorry. I know bad joke. It looks like the signal comes from “speed sensor #1” and runs right into the back of the combination meter. From what I’m seeing it dose not run through the ECU.
09-05-07, 08:19 PM
#5
Keeper of the light
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On the old cluster it runs pretty much directly into the gauge, but on the new cluster I was remembering it go through the processor on the main chip (not speaking about the computer ECU).
can you see that far into the unit david?
can you see that far into the unit david?
09-05-07, 08:38 PM
#6
Lead Lap
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There is a yellow wire coming from the 10amp gauge fuse, through the "speed sensor #1" and into the connector on the back of the combo meter. I can post the EWD tomorrow when I get to work.
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09-05-07, 09:10 PM
#8
Stock gearing: 4.27
New gearing: 3.76
After the swap, your actual speed will be 14% greater than what the speedometer will read.
The 3.76 gearing means that the driveshaft (and drive pinion) spins 3.76 times for each full rotation of the wheels (and differential ring). Your transmission is expecting one full ring revolution for every 4.27 driveshaft turns. But, after the swap, you will have spun the ring 1.14 times around for every 4.27 turns of the driveshaft (ie. the wheels are spinning at the higher rate than the transmission thinks they are and your speedo will be light, not heavy).
Thusly, your attainable top speed becomes higher, your speedo reads slower than you are actually going, and spinning the wheels requires more energy.
Perhaps the best benefit of the swap will be highway fuel economy. You will be able to go 85 and still get 20+mpg.
09-05-07, 09:36 PM
#10
your words above suggest that you have this backwards. re-read my previous post on the topic and you can see why it is that the speedo will rear improperly (and in what direction).
09-06-07, 08:23 AM
#14
Lexus Test Driver
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If its obd II can lexus just recalibrate it for you. I know they do that to domestic trucks and cars all the time when going with bigger wheels or different rear ends.
