how do I calculate what speedometer gear to use?

[bgracen]

I went from 235x75x15 to 31" tires and I have 3:55 gears. How do I correct my speedometer to read accurately? Thank you.

 

[Maniak]

You need to know a couple of things...

1: what is the difference from the old tire size to the new size (actual percentage).. or how far off is your speedo (what percent)

2: How many teeth do you have on your current speedo gear (driven gear)

Once you know those two you call a speedo shop and tell them you have an x tooth gear and need to change it x%. They can then get you the correct gear (or at least get you closer)..

If you can't find the gear you need I have a friend at a Speedo shop that can get it for you but any decent speedo shop or sometimes even the ford dealer can get you the gear.



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Mark
mark@legendz.com
http://mark.legendz.com
Off-Road and Motorcycle Information, Pictures and Movies
Click Dead Link Removed to see our Explorer Specs

 

[bcorff]

Search around the site for this and you will find all the info you need. You can get the gear at a dealership for around $10 and install it in less than 5 mins.

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Brian Corff
Dead Link Removed
"Beware the lollipop of mediocrity. Lick it once and you suck forever."

 

[Barnstormer]

Maniak: My '91 has an error of about 6 mph on speed. However, the odometer error is <3 miles in 1,000. How can I correct the speed error and not mess up the odometer?

Thanks in advance for any help.



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Barnstormer
'91 stock 4X4