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Old 09-02-2010, 05:08 PM   #1
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How to adjust the speedometer?

Yet another issue with my TJ. My speedometer says that I am going 3mph faster than I actually am. It's a 2000 sport model with the 4.0l engine and 5spd tranny.
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Old 09-02-2010, 05:15 PM   #2
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In your tranny should be a speedo gear, you need to know how many splines are on it. You also need to know your axle gear ratio and tire size. Next check somewhere like quadratech for the correct speedo gear.

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Old 09-02-2010, 05:20 PM   #3
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Oh and nasty not sure of your tire size but it sounds like they are smaller than factory. If so just change your tires to factory size. I was just assuming on my last post you had larger tires.
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Old 09-02-2010, 05:34 PM   #4
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I have 31" BFGs. Would I have to remove the transmission to change the speedo gear? Also, my tachometer sticks at 2200rpm (and stays there unless I hit it), how could this be fixed?
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Old 09-02-2010, 05:57 PM   #5
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Old 09-02-2010, 06:32 PM   #6
Knows a couple things...

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One more link to how to do this with a chart to tell you what speedometer gear tooth count to install. You just need to know your axle ratio and tire size to use that chart. Click on the chart to make it big enough to read... Changing Your Jeep Speedometer Gear
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Old 09-02-2010, 07:43 PM   #7
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Being 3MPH off is well within the margin of error. My Dad's brand new Buick is 4MPH off according to his GPS.
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Old 09-02-2010, 08:08 PM   #8
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listen to Jerry. he knows what he is talking about. i just changed gears in my 2000 tj auto. and i run on 33's. i called 4wd about the speedo and they told me to change to a 34 tooth speedo,... wrong! i'm running 5-8mph faster on my speedometer than i'm actually running. jerry told me to switch to a 36 tooth speedo and presto, back where i need to be.
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Old 09-02-2010, 08:30 PM   #9
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yeah some charts are wrong, jerry knows the correct ones. 3mph is prob "within factory specs" but i understand, and as far as how hard it is, did it today with 1 wrench and less than 5 min total. so its real easy, its located on the tail shaft of the transfer case, pull the bolt and it slides out, put the new gear in and back together, that simple
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Old 09-03-2010, 05:38 AM   #10
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Also what speed is it 3 mph off? The error from different size tires is linear. The error will increase as the speed increases.
2003 TJ, 33" BFG AT, 2" BL, 2" BDS spring lift, Truck Lite headlights, Homemade sunrider top.
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Old 09-03-2010, 07:08 AM   #11
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Am I the only person who doesn't hate math? Much easier and free to just remember the speedo is a tad off.... (kinda like me)


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