Speedometer Calibration?

[Kai SRT10]

How hard is it to recalibrate the speedometer?

My new PS2 front tires are a little smaller than my stock runflats, and this makes my speedometer read too high.

Anyone here had this done?

 

[dave6666]

http://www.roeracing.com/ProductCart/pc/viewPrd.asp?idcategory=29&idproduct=186

Works for Gen2. You might call them about your Gen3

 

[Viperless]

How hard is it to recalibrate the speedometer?

My new PS2 front tires are a little smaller than my stock runflats, and this makes my speedometer read too high.

The speedo is driven off the fronts on an SRT10?

 

[dave6666]

The speedo is driven off the fronts on an SRT10?

I think they are driven off the tire pressure sensor transmitter. Front or back? Dunno. Fronts make sense though. Would give real speed during a burnout.

 

[mjorgensen Woodhouse]

Gen 3 and Gen 2 are not the same. The speedo is calibrated from ABS to the PCM so unless you have a way to access this feature in the PCM you are stuck with the reading. The PS2 should not be significantly small enough to actually be causing an error of more than a mile or two per hour.

 

[Kai SRT10]

The PS2 should not be significantly small enough to actually be causing an error of more than a mile or two per hour.

It's more than you might think.

According to the tire manufacturer's specs it's about a 4 percent difference. Checking my speedometer speed against radar, I've noticed an even greater variation, about 8 percent (or 5mph variance at 60mph.)

At open road racing speeds (120mph+) this variance becomes pretty significant and makes it hard to accurately judge speed for computing time/distance and also for not exceeding "tech speed."

 

[mjorgensen Woodhouse]

Tech speed shmeck speed... now you can speed and not be doing anything wrong ;-)

 

[Viper Specialty]

if it came down to it, I could fab up a set of custom ABS tone rings so the Speedo reads correctly, but that would surely not be cheap.

I am not aware of any way to change the readings on the Gen-3's, as the ABS controller is the controller responsible for producing that signal, and it is a Bus commuication, not an analog signal.