Gotta quick question....I am putting my built 700R-4 in my new IROC and it has the 3.23 rear. The tranny in the old Camaro has the 2.73 Rear. What drive and driven gear ratio should I use to get the speedometer to read accuratly? I looked on 700r4.com and they look like they has the same drive gears, but different driven gears. The driven gears are the ones on the inside of the tailshaft housing, right?

 

Don't go by any calculators. They are wrong and do not give the same gears gm used. Best, most sure way, is to call gm and just ask what combo the 3.23 cars had.

 

Wait a minute... I am having a bit of difficulty understanding exactly what you are doing.

If you are swapping transmissions AND NOT changing the rear gear ratio, then there is no need to change the speedometer gears. Use the speedometer gears from the original car that you are putting the trans into. A new trans will not change your speedo reading.

 

Yeah the 3.23 rear uses the same red gear on the transmission output shaft, but it uses the dark grey cable gear. There's another post on here titled 2.73 to 3.42. Go to that thread and fireturd has the part # listed for the dark grey gear you need.