bear351c 10,260 Posted January 4, 2020 Hey guys, fitted my 9" with 3.5 gears, and changed the speedo drive to suit (3.55 with FMX) but speedo is still 10kays too fast. Reads 60 and GPS reads 50km/h. This will be out because my wheels and tyres were changed, and the new boots are taller. My question is, which way should I go to correct the discrepancy, more teeth on the gear drive, or less.?? It will be way easier and heaps cheaper to change the speedo gear than buy new tyres...... It's a cable drive in an XB, so Jaycar speedo correction boxes are a not an option. Cheers Bear. Share this post Link to post Share on other sites
deankxf 20,231 Posted January 4, 2020 say it has a 19 tooth gear in now. a 21 tooth will slow it down roughly 20% from what i understand (one tooth makes about 10% difference according to the mob i used to deal with back in the day) 3 Thom, bear351c and gregaust reacted to this Share this post Link to post Share on other sites
gregaust 315 Posted January 4, 2020 With 3.5's depending on tyre diameter usually I go with 20 or 21 gets it near spot on 2 bear351c and Thom reacted to this Share this post Link to post Share on other sites
bear351c 10,260 Posted January 5, 2020 Thanks fella's...... 1 deankxf reacted to this Share this post Link to post Share on other sites
bear351c 10,260 Posted January 22, 2020 Hmmm........ Popped it out, and is a 21 tooth. Might have to try a 23. Share this post Link to post Share on other sites