Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post - Correcting drive ratio for accurate speed

AlexTheGreek · 11-29-2012, 09:04 AM

Hi all,

I'm coming from the motorcycle world (Honda CBR 600/1000). This is my first "toy" car.

When I changed my final drive on my motorcycle, there was a speed sensor on the output of the transmission that I could jack into with a device to correct the speedometer. (SpeedoDRD or SpeedoHealer)

Does such a thing exist for calibrating new tires diameters or differential gear ratio changes so that the speed on the dash is correct? Does the speedometer read the speed from the output of the transmission or does it take it from the ABS which must have individual speed sensors?

And yes I know speedometers are not accurate because of the pull/slip characteristic of tires (Longitudinal Force versus slip ratio) and because of tire growth with increased speed, but I still want to be able to adjust it.

11-29-2012, 09:04 AM	#1
AlexTheGreek Senior Member Join Date: Nov 2012 Drives: BRZ Premium Black Location: NC, USA Posts: 122 Thanks: 33 Thanked 20 Times in 14 Posts Mentioned: 1 Post(s)	Correcting drive ratio for accurate speed Hi all, I'm coming from the motorcycle world (Honda CBR 600/1000). This is my first "toy" car. When I changed my final drive on my motorcycle, there was a speed sensor on the output of the transmission that I could jack into with a device to correct the speedometer. (SpeedoDRD or SpeedoHealer) Does such a thing exist for calibrating new tires diameters or differential gear ratio changes so that the speed on the dash is correct? Does the speedometer read the speed from the output of the transmission or does it take it from the ABS which must have individual speed sensors? And yes I know speedometers are not accurate because of the pull/slip characteristic of tires (Longitudinal Force versus slip ratio) and because of tire growth with increased speed, but I still want to be able to adjust it.