Getting ready to do a gear swap from the factory 3.23 on my Formula to 3.73. Been undecided about the correct installation kit. Some are master kits, some are standard kits, some are half kits.



Any idea which is sufficient for the swap? And understand the higher power band and acceleration increase, but does anyone have any pros/cons on swapping for taller gears?

 

In previous posts over the decades I don't remember anybody who didn't like the 3.73"s.But most members(I think)ran headers,cam,and torque converter upgrades as well.I think the speedometer would be off but there must be a way to calibrate it.What size wheels make a difference I think.Post a signature with what year car ect.Hope this helps.

 

How many miles on the car? At 20+ years old, assuming you have a 4th Gen, would be a good idea to use the master kit, with all the bearings. I would also add axle bearings and axle seals. In addition to the correct GL5 gear oil, you will need GM limited slip additive.

94-02 require flashing the PCM to correct the speedometer/odometer for the new gear ratio. Wheel size doesn't affect speedo calibration. Only the tire outside diameter affects speedo.

 

126K on the car. My tuning shop is gonna do the install, so he'll tune or flash the PCM for odometer accuracy.