Speedo Gear question
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,422
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From: Hartford WI
Speedo Gear question
Currently with my 3.07 D36 rear end, I have a 17 Tooth Drive and 42 tooth driven gear. When I change to the D44, would the Vehicle Speed Sensor change too? Or would I just change to the 15 tooth drive gear and be happy? TIA
Race Director
Joined: Feb 2004
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You will have to change the gears for sure. There is a formula in one of my tpis books that tell how. I Know that 3:73 gears need the gray drive gear with the 45 tooth driven gear. I do not know the correct gears for your application off hand. Maybe someone else will chime in. I will try to locate my book for the conversions.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by aklim
Currently with my 3.07 D36 rear end, I have a 17 Tooth Drive and 42 tooth driven gear. When I change to the D44, would the Vehicle Speed Sensor change too? Or would I just change to the 15 tooth drive gear and be happy? TIA
RACE ON!!!
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,422
Likes: 3,275
From: Hartford WI
Wonder why a 15 drive gear and a 42 driven gear is right for a 3.45 when according to calculator I should be going with a 15 drive and 41 driven
Stock tire size is 275 40R17 which gives a diameter of 25.66
Tire Rev per mile is 20168/25.66 which gives 785.97
The formula says that
driven teeth = (drive teeth X Axel Ratio X Tire Rev)/1001
= (15 * 3.45 * 785.97)/ 1001
= 40.63 teeth
Rounded up gives me 15 drive and 41 driven. So why does GM have a 15 drive and 42 driven?
Thanx
Stock tire size is 275 40R17 which gives a diameter of 25.66
Tire Rev per mile is 20168/25.66 which gives 785.97
The formula says that
driven teeth = (drive teeth X Axel Ratio X Tire Rev)/1001
= (15 * 3.45 * 785.97)/ 1001
= 40.63 teeth
Rounded up gives me 15 drive and 41 driven. So why does GM have a 15 drive and 42 driven?
Thanx
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by aklim
So why does GM have a 15 drive and 42 driven?
Thanx
Thanx
RACE ON!!!
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Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by aklim
The dealership has no real answer. Anyone wanna speculate or correct my equations?
Originally Posted by CFI-EFI
*I* can't answer for GM. Maybe you ought to ask THEM.
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