Gear and speedo calibration

[Cellamotors]

I have 3:73 gears in my 94 viper, but the faster I go the less I'm really going by the speedometer reading.
@ 120mph really feels like 100' but if I. Going 50 it is more like 40..... Where or how do I get a speedo calibration box?
Thanks

 

[vancouver-gts]

http://www.gounitrax.com/

 

[uvbnbit]

don't forget to consider your tire size/diameter too. (if not stock)

 

[Cellamotors]

Tires and wheels are stock.....

 

[mrbob]

get a yellow box and i will tell you the setting for 3:73 rear gear . thats what i used on my 1994 , pm me if you need assistance

 

[SNKBYT]

Do you know the dip switch setting s for 3.73 gears? I have a calibration box for my 3.45 gears. I am installing 3.73 and looking for the correct dip switch settings. Any have these?

 

[Talon]

3.73 gears in the Viper have got to be just ape **** nuts! I'm impressed. Can you even idle in the rain or do you just spin your tires? lol.

By the way if you want to do some quick and dirty calculations you can use this website to determine what you speed should be at a given RPM, then you will at least know how far off you are: http://www.advanced-ev.com/Calculators/TireSize/