Speedo change after regear?! - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 9 Old 06-25-2019, 07:05 PM Thread Starter
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Speedo change after regear?!

Hey guys, I put in new 4.56 gears and 35 inch tires and I'm at a loss how to reset the speedo, it is almost definitely.wrong.and I'm worried I'll burn out my new pinion bearings going over 55mph.

I flashed the computer with the new mods with my flashcal already but no difference
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post #2 of 9 Old 06-25-2019, 07:59 PM
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Your not going to hurt your bearings by driving over 55mph.

Sent from my LM-V405 using Tapatalk
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post #3 of 9 Old 06-25-2019, 08:01 PM Thread Starter
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I dunno, I got worried enough by everyone screaming about the break in period. I definitely.dont want to have to open it up again
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post #4 of 9 Old 06-26-2019, 05:24 AM
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download a speed app with gps and see what it says compared to what the jeep says.

The only way to change the speedo on modern jeeps is to flash them with some sort of programmer, which you have said you have done.

Did you measure the tires exactly or just assume they are 35's?

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post #5 of 9 Old 06-26-2019, 06:22 AM
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what year is it? I think with the 2013 and newer JKs you have to adjust just the tire size and not the gear ratio in the computer. Something about it getting the speed calculation from the wheel sensors, which are not affected by the gear ratio.

So if you flashed a new gear ratio only, go back and try flashing the new tire size instead maybe. I hope that makes sense.
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post #6 of 9 Old 06-26-2019, 06:34 AM Thread Starter
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Makes great sense! Thanks. I resized on a mother thread I hadn't measure my actual tire size which is 34. Feel.cheated haha anout to run with new size in computer
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post #7 of 9 Old 06-26-2019, 06:37 AM
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Just don't go 88 mph.. no telling what the future will look like.

Chase Weston
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post #8 of 9 Old 06-26-2019, 06:46 AM Thread Starter
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My luck I'd go to the past and have to do.the work all.over again
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post #9 of 9 Old 06-26-2019, 12:07 PM
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What others have already said.

With your Flash Cal, you enter the new gear ratio, AND tire size.
Use the actual height measurements with the tires mounted, aired up to the pressure you will be using, and the weight of the Jeep on the ground.

Also be sure to select to correct transfer case (Rubicon vs other).
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