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How many teeth do i need for speedo Gear.

Old 05-09-2004, 06:17 PM
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geoff4961
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Default How many teeth do i need for speedo Gear.

Well, The results are in
I curently have 19 teeth on the speedo gear that goes in the trans and I know something is wrong. I took the cable apart and re-greased it and now I need to figure out the hard part. I drove 2 miles at 60 MPH and it took 2.27 min 2.28 min and 2.31 min I also took a reading at 1 mile tha was 1.14 min can any one tell me how many teeth I need on that gear or how do i figure it out.
I thank you all in advance,
Geoff
Old 05-09-2004, 08:45 PM
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Aflac
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Default Re: How many teeth do i need for speedo Gear. (geoff4961)

It all depends on your transmission, speedo gear and tire size if you have changed any of them, the gears will be different. If I remember right, mine (77 vette, 350 auto and 3.08 gears with 225-70-15 tires) is a 38 or 39 tooth. They are differentiated by color and teeth, but you probably already know that. I used to have a link to the colors and teeth counts. If I find it, i'll IM it to ya. :seeya
Old 05-10-2004, 08:54 PM
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BKbroiler
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Default Re: How many teeth do i need for speedo Gear. (geoff4961)

I recently changed rear ratio and used the following method to correct the speedometer:
Your speedo reads 60 and it takes 1.14 minutes to cover a mile. Therefore your speedo is reading high because you must be going less than 60 since 60 equals 1 mile per minute. You need to add teeth to the driven gear to slow down the speedo. Since you are now 14% off (1.14 min per mile), you need to multiply 19 teeth now by 1.14. That works out to 22 teeth. Thats what I would try. Zip has gears for about $7 each.
Old 05-10-2004, 09:03 PM
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markdtn
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Default Re: How many teeth do i need for speedo Gear. (BKbroiler)

You can also get gears at any GM dealer and save the shipping.
Old 05-11-2004, 09:37 AM
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jbroughton
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Default Re: How many teeth do i need for speedo Gear. (markdtn)

Yeah, I just picked one up last week from the local Chevy dealer... about $5.

Old 05-11-2004, 09:51 AM
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SanDiegoPaul
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Default Re: How many teeth do i need for speedo Gear. (geoff4961)

Go by speed no the odometer. Each tooth on the gear is about 3MPH

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