Thread: Speedometer gears-TH350, which one do i need?

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This is not a Turbo 350 ... but the principal is the same ...
You need to know the rear end gear ratio and the height of your rear tires ...

The speedometer gears are color coded ... so you will know the number of teeth on the shaft ... and then adjust. You may have to change both ...

then go here ...

http://www.bgsoflex.com/speedo1.html

Simple really ... to get it dead on ...
Look here ...

http://www.transmissioncenter.net/sp...____va.htm#350

Thanks, but how would I know how many "speedometer revolutions per mile" i need to type into that chart? And is the plastic color coded gear the drive dear or the driven gear? My car has a 30" tall tire and a 3.00:1 rear end ration btw.

tire rev per mile 20168/30 = 672
672X 3.00x drive teeth / 1001= driven teeth
drive is on the shaft driven on speedo cable what color is the drive gear?

Originally Posted by joeybsyc

Thanks, but how would I know how many "speedometer revolutions per mile" i need to type into that chart? And is the plastic color coded gear the drive dear or the driven gear? My car has a 30" tall tire and a 3.00:1 rear end ration btw.

Type in 1000 ...

There are 4 different gears available for the driver ( the output shaft ) and they are either a 7, 8, 9, or 10 ...

With your rear in the ( 3.00 ) ... and your tall 30 inch tires ... you need the driver/driven ratio to be 2 to 1 ...

That means ... the number on the driven ... needs to be 2 times what is on the output shaft.

If your output shaft has a 7 on it ...
You need a 14

If your output shaft has a 8 on it
You need a 16

If your output shaft has 9 on it
you need a 18

If your output shaft has a 10 on it
You need a 20



There are no 14 tooth and 16 tooth available
The available driven gears are 17, 18, 19, 20, 21, and 22
So you need at least a 9 on the output shaft ...

I suggest a new bullet also ...