hagausaf

you have to gun the Jeep to get over the hills and mountains here which is why my mpg's have always blown. But I was getting 10 mpg before my regear and ProCal so I'm not complaining about 14-15 mpg. Cant use the Superchips like you can on my '11 which sucks for power.

robsjeep9

Yeah that's too bad cause the Superchip did help out the cause(driving a jeep lol) a bit for mpg.

ridelots24

Thanks for the info - but i've hit a snag. My Diablo Sport tuner (U7137x) does not support flashing info for gear changes. Verified today, their tech line said that they dont have another product to help me either - he suggusted i call the jeep dealer.

So my question is: what tuner for the Jeep allows the user to change the gear settings? please mention the product cost if known.

btw - my mpg's have settled back down to 14's....

thanks & ridelots!

JPop

Wow! I can't believe they wouldn't have that, but you can still get it right by changing your tire size.

aldaman

Is your JK a 2010? If so Tuners such as Superchips & Hypertech allows you to change your gear settings. There is also the Procal module from AEV. It is not a tuner, but it allows you to change the gear settings. Since you already have a tuner maybe you can also use the Procal. I am not sure if they are compatible though. If not you can always sell your current tuner and purchase either the Superchips or Hypertech....

ridelots24

Ok - this may be a dumb question. I did change the tire size using my diablo. but does it make a difference if the jeep thinks its running 35" tires with my old 3.73's? or will it figure out the resistance is less with the 4.88's and shift appropriately?



Aldaman - thanks for the info on superchips

JPop

OK, so you went from 3.73s to 4.88s, if I have that correct.

3.73 / 4.88 = .764

So lets say your 35s have an actual measured height of 34".

34" x .764 = 25.976"

So if your Diablo will take a 26" tire you have basically trick phucked it into calibrating for your gear change.

ridelots24

Jpop - i'm sure i may be missing something obvious here.....but if set my tire size to 26", wouldn't the speedo be way off then? but if i get what your saying....it will shift better..?

This is how i looked at the math. i have tire size set at 34.50 or
Circumfrence of 108.38"
108.38/4.88 = 22.2" / revolution
108.38/3.73 = 29.05"/ revolution
difference of 6.8" / revolution
108.38"-6.8" = 101.58" tire circumfrence
101.58 / 3.1416 = 32.33" tire height to fool the computer that 4.88 is stock ratios.
this is fun to think about!

before someone posts the RPM / Gear ratio chart the difference between the two ratios' at 70 mph 3.73=1730 rpm and the 4.88=2264 rpm diff of 534 rpms. maybe i'm just wasting band with on JK forums.....even if i tweaked the computer, would the 4 speed auto even shift differently?

If you or others have re-geared (on an auto) then flashed the computer to reflect the change what difference did it make? mpg savings? shift points? when i talked to the guy at Diablo, he made it seem like i didnt need to bother with it.

I'm sure when this thread reaches the answer we will be at the nexus of the universe!

JPop

Wow, that's a lot of math and a lot of it unnecessary.

Take the rpms from the gear chart, divide them out, you get .764

Take the gear sizes themselves, divide them out, you get .764

Take your inches per revolution numbers, divide them out, you get .764

Put the beer and the bong down, divide them out, you get .764

That's what you need to multiply your tire height by to get your speedometer correct in the absence of the Diablo having differential calibration. With having your speedometer correct you will shift at the appropriate speeds given your throttle position. Without it, you'll be short shifting an already under powered vehicle.

FlameRedJK

hahahahahahaha