speedo gears?

Question

I was clocking my speedometer the other day with my GPS (I have 31" tires and 4.56 gears on my 98 TJ SE) and I found that the speedometer was reading

64mph at an actual speed of 60mph (on the GPS). The SE came with a 40 tooth gear, so I calculated that I need a 42.666 tooth gear. ;) I figured I'd go conservative at 42 teeth. I called Jeep parts at three different dealerships and they all say that the gears go up to 41 teeth and that's it. Does anyone know where I can get a 42 tooth gear? 41 is hardly worth the money to put it in. That's around a 1.5 mph correction. TIA TJim

FrankW · Accepted Answer

Just curiousWhat is the accuracy of a GPS?I own a GPS And I think I remember reading that there is a tolerance.+/- something.TJim wrote:

TJim · Answer

*Everything* has a tolerance of +/- *something*...;)

L.W.(Ãill) · Answer

Hi Jim,     I think you be going the wrong direction. Two sites I use tocalculate the number of teeth agree, you should use 37 teeth

TJim · Answer

I know, Bill, but the chart is wrong for the SE as far as I know.  My SEcame with 29" tires and 4:11 gears and had a 40 tooth gear in it.  The chartshows a 38 tooth.If I'm reading 64mph at 60mph and I have a 40 tooth gear, The speedometercable is turning too fast and I need a larger gear.  40 * 64 / 60 = 42.67teeth.TJim

L.W.(Ãill) · Answer

I corrected my reference site to:         God Bless America, ßill O|||||||Omailto:          wrote:

TJim · Answer

Looks good, Bill. The only thing I find distracting is the "Go Jeep" flag on the mouse pointer, although, I never lost the pointer the whole time I was checking out the page. ;) So, it seams that, although I need a 42 tooth gear, the biggest one available is 41 tooth, right? Rats. Good thing I don't have bigger tires... TJim

speedometer

speedo gears?

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