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Old 05-11-2006, 10:47 PM   #1
75stepside
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Speedometer calibration - TH350 where to begin?

Ok guys, i finally got my speedometer to read!!! I have a Garmin GPS and so i had it along with me to see how accurate i am... well, i'm way off. My in dash reads 55 mph when i'm doing 35 mph!!! and reads 80 mph when i'm doing 55 mph! so, i need to get it calmed down. Here is the current configuration:

TH350 Tranny
10 Teeth Drive Gear (red or purple; i think its 10 teeth??)
19 Teeth Driven Gear (natural)
3.73 Rear Axle Ratio
27" Rear tire size (295/50/15)

what gears do i need to change? both or just one!?!? i have no idea what my original tire size/rear axle ratio was or if these tranny gears were even installed by the factory or just put in... any direction would be helpful.
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Old 05-12-2006, 12:10 AM   #2
79BIG10
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Re: Speedometer calibration - TH350 where to begin?

Here's 2 sites for you

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

http://73-87.com/7387garage/drivetrain/speedo.htm
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Old 05-14-2006, 05:24 PM   #3
jimfulco
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Re: Speedometer calibration - TH350 where to begin?

http://novaresource.org/speedo.htm

You'll need tire diameter & rear end ratio.
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