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Help me pick my spedo gear

G

GTA6T7

New Member
I know there are calculators out there to help with this but I thought I'd try it the easy way and ask someone who already figured it out to just to tell me which gear I need to buy.

I have a C4 trans, running 355 gears with 25.7" tall tires. Anyone else running this combo? What gear did you end up buying to get your speedometer working again? Thanks
 
Same combo and the calculation that came out was the purple gear IIRC. (Can't remember the teeth count) I'll go back and pull the receipts and check to verify. I do know that my speedometer is still off by approx. 5 mph on the high side. I checked the odometer and it's reading 1.2 miles for every mile. Let me look through everything to make sure I'm correct.
 
A little misinformation on my part. Tires are standing at 24 3/4". Keep in mind this is with the car on the ground. NPD part number is 17271-B on the new gear. The package doesn't have the tooth count on it. With your tire being a little larger that may be the part number you'll need.
 
It works out that you need a 19.5 gear. So if you go with a 19 tooth gear your speedometer will be a bit faster than you are going and if you go with a 20 tooth gear it will be a bit slow than you are going.
 
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