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Speedo question...


Sean 83ZXT

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OK I have a stock (for the moment) 83 ZXT that I'm building up and I was wondering about the speedo. First of all it only hits 85 and 2nd of all if I change the tire size I know it will be off. Well how does an electronic speedo work? And if I change tire size is it correctable on one of these?

 

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Future 12 sec L28ET Driver

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Sean,

 

I cant answer the "Electric Speedo" question for ya; but I can help you w/the effects of a tire change.

 

If you are increasing in tire diameter (Larger Tire) then you can calculate the effect w/this formula:

 

Actual MPH = New Tire Diameter/Old Tire Diameter x Indicated Speed

 

*The Actual MPH is the mph you're doing after the tire change

*Indicated Speed is the speed your doing prior to the tire change (pick any speed)

*The forward slash represents "Divide" so you will divide the New Tire Diameter into the Old Tire Diameter...once you have that answer you will multiply that by your Indicated Speed.

 

Once you know the difference in Speed you can then make changes to the Drive/Driven Worm Gears in the Trans to correct for the MPH difference caused by the change in Tires.

 

Hope that Helps.

 

Kevin,

(Yes,Still an Inliner)

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Guest Anonymous

I have an Autometer Phantom Series electric speedo and it has a calibration switch that can be reset at any time. Reads to 160 mph. Wasn't cheap, but looks great in the dash.

 

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'71 240

'91 TBI 305,700R4 w/ shift kit

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