Almost4x4

Hi guys

Managed to get the graph uploaded as a picture..... was struggling.
It is for my 2012 Jeep JK, Manual gearbox with 3,21 axle ratio and NON STANDARD BFGoodrich 33 x 12.5 x 15 tires.
It the calculations i actually used 32" for the tire size as this is closer to reality. I measured the ground distance of one tire rotation and calculated it back to a real tire size.

Here it is:

[ATTACH=CONFIG]1284[/ATTACH]

Regards
Paul

Hi Guys

So i didnt get it rite....
Click on this link to see the graph properly.


p499-3-21.html


You will see that for desert driving:

1st gear is good, when you are driving between 30 and 65 km/h and need lots of power.
2nd gear is only good when you are driving fast..... rally style or medium speed on flat ground where reduced power is ok @ 2000 rpm.

For the road:
6th is useless
5th is OK, if you drive fast or like low rpm for long drives at 120 km/h.
4th is where i drive most of the time on the highway @ 120 km/h for short trips.
3rd to 1st are normal (great)

pwood;23282 wrote:Hi guys

Managed to get the graph uploaded as a picture..... was struggling.
It is for my 2012 Jeep JK, Manual gearbox with 3,21 axle ratio and NON STANDARD BFGoodrich 33 x 12.5 x 15 tires.
It the calculations i actually used 32" for the tire size as this is closer to reality. I measured the ground distance of one tire rotation and calculated it back to a real tire size.

Here it is:

[ATTACH=CONFIG]1284[/ATTACH]

Regards
Paul

Paul, great efforts, but the pic is so small that we cannot see anything...

pwood;23284 wrote:Hi Guys

So i didnt get it rite....
Click on this link to see the graph properly.


p499-3-21.html

Good effort, but can you name the axis and other values in the graph? It took me a while to understand it.
Do I read the graph correctly, that you can make on 2nd gear at 6000 rpm 113 km/h?

Hi Capri

Yes. 6000rpm gives 113 km/h in 2nd gear.

I will label the axis..... good point.

Regards
Paul

pwood;23291 wrote:Hi Capri

Yes. 6000rpm gives 120 km/h in 2nd gear.

I will label the axis..... good point.

Regards
Paul

Thanks, are the values in graph theoretical or measured on your toy?

hi paul

I like the graph you made and I think ill make one too for my car. Maybe it will help my decision whether to re-gear or not if i plot both 3.73 and 4.56. Perhaps ill try to add the torque curve on the opposite axis which might give more insight not sure if I can find excel values for it though.

Hi guys

Capri - I have re calibrated my speedo for the bigger tires and the speedo, GPS and graphs are exactly the same.
i have even measured the exact tire size at 8 psi and 24 psi, to get real world road vs off road differences.

Sami - if you want I can give you the model numbers of the gearbox, transfer case. The link I gave earlier needs the model numbers or ratio numbers. Remember that 6th changed in the 2012 manual and is not well documented. The gearbox is the same model as the 2011....

regards
Paul

Paul, thank you for simplifying this subject. You have made it easy to understand. And it also points to many new drivers who upgrade for looks and forget that it has costs elsewhere. Have passed on your details to one of my friends who own a Wrangler and has a need for advise.

Going by your signature you are running 285/75/16 BFG's on your 2012 FJ so why did you feel the need to regear it ?

I have a 2010 FJ and have the same tires and don't have any issues driving it around on and off road except for a loss in fuel economy.

I have a TRD cat back , hi flow filter and a UNICHIP though !

Regarding the supercharger its going to be a long wait for the TRD to come out ....look at the URD option