I recently install 3.55 gears in my 85 GT. The car has a 5 speed with the stock sized tires 225/60R/15. Of course my speedometer was way off with the gear change. The factory speedometer gear is a 16 tooth. I installed a 20 tooth but it still seems like I'm off by about 5 or 6 MPH. Will a 21 tooth get me close or am I destined to have an F%$&$-up speedo.

 

21 tooth should be right on the money.

 

i think u can get the right gear at steeda.com for 6.00

 

Here ya go:

http://www.geocities.com/mgnedell/no...ch/speedo.html

 

Turns out all the sites that call for a 20 tooth speedometer gear to match with 3.55 gears, 225/60R/15 tires, and 5-speed were wrong. I had a cop hit me with the radar gun and I was 5 MPH slower then my speedometer read. Threw in a 21 tooth and now I'm right on.