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Right Speedometer gear and drive gear
#1
Hi folks,

I have a 3.50 gears ratio with a 4 speed manual trans and 275/60 R 15 tires at the back. The problem is, the speedometer reads a lot less than the real speed, so I assume I need a new speedometer gear. Which one should I use now - my maths (I am bad at that) results in a 20 teeth. Is that right? Which drive gears should I have - 7 teeth?

Thanks,

cheers,

Tim

Tim

Never drive faster than your guardian angel can fly Angel
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#2
You probably do have a 7-tooth drive gear in the transmission. However, for that diameter of tire (28-inches/710mm) my calculations show that you need an 18 tooth speedometer gear.
Attached is a spreadsheet with a calculator and information.
[attachment=21306]



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
Hi Don,

thank you very much, that is EXACTLY what I needed Smile

Cheers,

Tim

Tim

Never drive faster than your guardian angel can fly Angel
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