I have searched and didn't find what I was looking for so here goes:

I have a 88 Iroc 700 r4 with 16" rims 245/50/16 tires. Currently running factory 2.73, but changing to 3.42.

I know the driven gear should be a 41t (with a 15t drive), but what is the factory drive gear for this combo?

15t hopefully?

Thanks, Mike Jones

 

Have a GM parts clerk reference the 91-92 RS V6. They use the 3.42 drive/driven gears.

 

Actually I want to know what the drive gear is for a 88 Iroc with a 2.73 rear gear and stock 245/50/16 tires and 700r4.

I want to avoid changing the internal gear if at all possible on the 3.42 conversion.

Thanks, Mike Jones

 

go to www.700r4.com and click useful tools, use the speedo gear calculator ,you are incorrect , you need a 40 tooth driven.....then take out the speedo sensor, which im assuming you have, unless you dont have an electronic speedo, im just trying to help maybe im wrong, however if you take out the sensor youll see the drive gear, if its grey its 15 tooth, if its red its 17 , go to this link and scroll down youll see all the part numbers for gears, hope this helps https://www.thirdgen.org/newdesign/faq/thirdgen.shtml

 

If your car had the 2.73 gears, it will have a 17-tooth drive gear and 37-tooth driven gear. Both gears are red. Unfortunately, you will need to change both gears if you want your speedo as exact as possible.

The two red gears is what I had, and it is confirmed here:

https://www.thirdgen.org/newdesign/tech/