I have 2013 jku, 05 front, 00 rear. Artec 60 tooth tone rings, running 5.13's and 37 mtr's.

My math
52/60*36.9=31.98 tire size for speedo compensation
52/60*5.13=4.446 to compensate for gear ratio.

Is everyone just tuning to closest ratio for gears? Both my flashcal and procal have set gear options. I have it set to 4.56 and dont have any lights but get an occasional loss of 4&5 gears. What programmers are everyone using?

 

You need to
Set tire size measured on vehicle, then set gear ratio that the diffs have and your spedo will be correct

 

The flashpaq I'm pretty sure has a ton of gear ratio options and can definitely set to 5.13.

 

Don't forget, its nothing more than ratios. I am running ford axles with 60 teeth tone rings. I have 4:88s with 38inch tire and I am running 4:10 to 32 inch tire ratio and it works great. You can move either side up or down.

 

Thanks 2climbbig, I reprogrammed at lunch. 4.56 and 32's. Speedo seems dead on with my gps app. Shifted fine. I'll run it like this and see how she does. Big wheeling event this weekend at Disney, dont want to spend the weekend fixing crap!

 

That is Great. If you start having issues with your tranny, you can play with your shift points to adjust for that.

 

That's actually wrong for 2012+ JKs. The tone ring count is 60 on the swap axles. The auto trans has a sensor that counts the revolutions vs the tone rings and engine. It doesn't care what the speedo says. What it cares about is that for xx speed of the trans, it is getting xx pulses based on the gear ratio. You need to trick the trans into thinking things are cool by changing the gear ratio. So, if you have 60 tooth rings and 5.38 gears, you set to 4.71. Tires size makes no difference to the system. May lighten your wallet if you're speeding and don't know it though.

You can likely get away with say 4.56 or 4.88, but then you're riding the edge of percentage off and are likely to encounter random limp mode issues. Best is to get a programmer that will let you choose an exact ratio, such as Aeroforce.

 

Good to know as I plan on doing 1 ton swaps pretty soon

 

I love it when a sponsor lends a hand!! Thanks for your input!!

 

Yup! Ditto!!