Jerry Scott[CO]
Viper Owner
Here's the way I would try to calibrate it. You will need the help of someone who has a Viper with the standard 3.07 rear end.
Run the stock Viper on the street in say 4th gear. Pick say 2000 rpm on the tach and observe and write down what exact number the speedometer gives for this rpm with the stock 3.07 differential. Now do the same on your car with the new 3.54 differential, by running the car on jack stands at the same rpm in 4th, but now your speedometer must read 3.07/3.54 (.8672) times the previous reading. If, for example, say the stock rear end reads 50 mph in 4th at 2000 rpm, you now want your car to read .8672 x 50 = 43 mph. Simply adjust the rocker switches by trial and error, until you get this new lower speed on the speedometer while running the engine at 2000 rpm. Now check it out by running next to a standard Viper on the street. I have not tried this, but it seems that this should work. Respond with a post if you try this and it works.
Jerry Scott
Run the stock Viper on the street in say 4th gear. Pick say 2000 rpm on the tach and observe and write down what exact number the speedometer gives for this rpm with the stock 3.07 differential. Now do the same on your car with the new 3.54 differential, by running the car on jack stands at the same rpm in 4th, but now your speedometer must read 3.07/3.54 (.8672) times the previous reading. If, for example, say the stock rear end reads 50 mph in 4th at 2000 rpm, you now want your car to read .8672 x 50 = 43 mph. Simply adjust the rocker switches by trial and error, until you get this new lower speed on the speedometer while running the engine at 2000 rpm. Now check it out by running next to a standard Viper on the street. I have not tried this, but it seems that this should work. Respond with a post if you try this and it works.
Jerry Scott
