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Discussion Starter #1 (Edited)
Can anyone help me figure out what speedometer gear I need?
I have a C-6 tranny with a 19 tooth gear. I will have 27.8" tall tires and 3.70 gears. I am going to send an order in to Dennis Carpenter and want to get the right gear. Also have a 3.25 punkin I may use if I take a road trip. What 2 will I need to get?
Thanks
 

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How many drive teeth do you have on the output shaft?

David
 

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Discussion Starter #3 (Edited)
If you mean the teeth on the end of the output shaft where the driveshaft goes in -31 :confused: duh.
If it's inside the tranny I don't know. I bought it from a guy who raced a 514 Mustang and decided to go with a c-4.
 

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The spiral teeth cut into the output shaft that drive the speedometer driven gear on the end of the cable.

David
 

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The spiral teeth cut into the output shaft that drive the speedometer driven gear on the end of the cable.

David
Whats the best way to count those without taking the tranny apart?
I'm in the same boat, FMX and 3.25 rear gears and I'm running a gear for 3.00 gears.
 

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Discussion Starter #6
Was talking to my Ford buddy last night and he said something about the gear inside the tranny being color coded? If this is the case my 70 year old buddy will have to crawl under it as I'm a bit color blind :rolleyes:, oh well!
 

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Colored drive gears are only on manual transmissions. Autos have the teeth cut right into the shaft. Depending on the tranny and your ability to get a good view, I either count the ends of the teeth (spiral is confusing to the eye) or mark a tooth with chalk or marker and carefully count across the spiral. The other method is to put a driven gear in and count the driveshaft rotations to get one full revolution, then divide into the number of teeth on the driven gear to get a drive gear tooth count. So, a 16-tooth driven gear and 2 shaft revolutions would be an 8-tooth drive gear.

David
 

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Discussion Starter #8
Colored drive gears are only on manual transmissions. Autos have the teeth cut right into the shaft. Depending on the tranny and your ability to get a good view, I either count the ends of the teeth (spiral is confusing to the eye) or mark a tooth with chalk or marker and carefully count across the spiral. The other method is to put a driven gear in and count the driveshaft rotations to get one full revolution, then divide into the number of teeth on the driven gear to get a drive gear tooth count. So, a 16-tooth driven gear and 2 shaft revolutions would be an 8-tooth drive gear.

David
David,
Thanks for your usual expert advice, now if I can just follow it :) haha
 

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Discussion Starter #9 (Edited)
My Gal's tranny has 9 drive gear teeth :D

Edit- I've tried 3 different calculators and have gotten 24 each time. I'm sure the trans has 9 teeth, I can count that far???
 
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