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Old 07-04-2002, 06:15 AM
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Talking Speedometer Gear Change ?

Yesterday I had the Gear ratio of my 8.5 inch Chevy 10 Bolt changed from 2:56 to 3:73 and added an Eaton posi. The car has a Chevy TH 350 trans with gear ratios 1st gear 2.52, 2nd gear 1.52, 3rd gear 1.00.
The rear tires are 245/60/15 which calculates to a tire Diameter of 26.57 inches.

My questions: 1) Where can I buy a new speedometer gear ?

2) What information must I provide ?

Thanks

Joe

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Old 07-04-2002, 04:05 PM
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Talking

joe,

i think if you go to a GM dealer and give them your tranny model, rearend ratio, and rear wheel diameter, they should be able to find you the right cable.

good luck,

JB
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Old 07-04-2002, 04:45 PM
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Talking

Found the answer in "Chevy High Performance" magazine April 2002, pg. 135

(New Gear Ratio) minus (Old gear ratio) all Divided by the (Old gear ratio). This gives you the percent increase in the number of turns of the driveshaft.

Then add (the percent increase) to (the number of teeth on the current speedometer gear). For instance: Old ratio 3.08, new ratio 3.42

3:42 - 3.08 = 0.34

0.34/3.08 = 11%

Say the current speedometer gear has 20 teeth

20 + 11% = 22
So your new speedometer gear needs to have 22 teeth.

Hope this helps.

bigjoedo

[ July 04, 2002: Message edited by: bigjoedo ]</p>
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Old 07-04-2002, 06:52 PM
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Hey there Big Jodo, I see you are helpoing me again. I about I bring my truck to your place, I'll bring beer and hotwings and we can finish these rears together. I am going to print this page so I keep all this wonderful intell.
I owe you twice now!
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