I have a 97 cummins auto 4x4 and i put bigger tires on it (32") and it threw the speedo out, i set my cruise at 108km/h and i got a ticket for going 117km/h sooo i want to know how to recalibrate the speedo. I heard that its a gear you change. does anyone know how to do it, and where i can find the parts and what parts i need.

Thanks

 

here is an idea get a garman gps its got a speedo on it and that is what i have been using for about a year know i got mine a wallmart for a bout 150 bucks

 

i thought about it but i just want my speedo

 

There are different tooth-count gears, to accomodate changes in gear ratios/tire sizes. They won't account for every ratio or tire size- I know that the Quadratec catalog (for Jeeps- I am using this as an example) has a chart with tire size/gear ratios, and what tooth count gear to get. In some cases, you can get close, but not perfect.
The previous owner of my truck marked the speedo, using a GPS for the actual speed, for 70 mph. Not everyone will accept that solution, but it works for me.

 

Assume you are 9 kph faster than speedo reads?

Getting a ticket for 9 kph seems a little vindictive. Are you in Ontario?

 

The spped limit was probably 100km/h, so 17 over is a realistic ticket.

 

Try this page for lots of speedo information. http://www.transmissioncenter.net/sp...__va.htm#dodge. Including links to speedometer calculators like this one http://www.bgsoflex.com/speedo1.html.

 

If you have a shop recalibrate your spedometer and take proof of the recalibration to the judge, they may be willing to waive the ticket once.... I've seen it happen before and might be worth checking into in your locality.