Speedo Gear Tooth Difference - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cwilkie · 07-27-2006, 12:43 PM

I am still fighting with my truck. Now I am working on getting the speedometer accurate. I have a 45 Tooth Driven gear and at 65mph the speedometer in my truck reads 53mpg. I put another driven gear in (didn't count it, but I assume it had less teeth) and at 65mph the speedometer was reading 57mph. I have heard that for every tooth difference there is a 5mph change in speed at the speedometer. Is this theory right? My Fiance` was nice enough to help me out with the acutal speed. Please help a guy out. Thank!!

Chance

07-27-2006, 12:43 PM	#1
cwilkie Chance Join Date: Sep 2001 Location: Belcourt ,ND, USA Posts: 750	Speedo Gear Tooth Difference I am still fighting with my truck. Now I am working on getting the speedometer accurate. I have a 45 Tooth Driven gear and at 65mph the speedometer in my truck reads 53mpg. I put another driven gear in (didn't count it, but I assume it had less teeth) and at 65mph the speedometer was reading 57mph. I have heard that for every tooth difference there is a 5mph change in speed at the speedometer. Is this theory right? My Fiance` was nice enough to help me out with the acutal speed. Please help a guy out. Thank!! Chance __________________ 1968 Chevrolet Stepside BB 396 w/TH400 1972 Chevrolet 3/4 Ton 4x4 BB 496 w/TH400



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