'Experienced driver but Jeep Newbie' question

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Jeepnomad
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Hi

After driving a Pajero for the last 10 years finally bought a Jeep Sahara Unlimited Automatic 2007 model - came with a 3 inch lift kit, Mopar air intake, 17 inch Cooper tyres, rack and pinion done, aftermarket exhaust etc (this is my first Jeep so not sure what more was done to it)

Heard about the problems with JK engine overheating and installed a hack job transmission cooler in series with my existing cooler.

The question is

What is the best gear to drive in the following situations

1 Short (say 40-50 ft) but steep incline - have to go over the lip and dont want the car to jump into higher gears and lose torque - i.e need short burst of maximum torque

2 Long but not so steep incline and want to go as far as possible up the dune

In the Pajero i could control and shift as i wanted with the Steptronic - but how do i handle it in an Automatic Jeep.

What is the difference between driving 4H in gear 2 vs driving 4L in D - any recommendations
Finally there is a switch that says O/D off - should i activate it?

Any suggestions and comments welcome

Tks

Jeepnomad
C N Sreejith
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Jeepnomad;41744 wrote:Hi

In the Pajero i could control and shift as i wanted with the Steptronic - but how do i handle it in an Automatic Jeep.

Jeepnomad
When I saw "control" and "shift" together, for a moment, what came to my mind was the computer keyboard :)
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matts
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Do you know what your differential ratio is it will be something like 3.26 or 4.1 or 4.86? And could you tell us the tyre size (17in is the rim size) it will look something like 315/70/17 or 32/12.5/17.

Then we can give a good estimate, so many things can be changed in a jeep and tyre size and diff ratio have a quite big effect. The auto vs manual also makes a difference as the manual gear ratios are different so someone with an automatic will have to help you on the overdrive question mine is a manual.
Orsomucca
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I think that more than theory this is the case where it's just feeling. A steep incline can be done in 1st if you are going slow or in 2nd if you are approaching with good speed...it depends from the situation.

Personally I'm not a big fun of low gears high rev in the desert, and I think that our big engines can better handle when in the 3000/4000rpm range. But again this is more feeling than theory

as well as I'm not a big fan of 4L, unless any of the gear in 4H suit my needs

Regarding driving in D, for me is a big NO. Probably because this is my first AT but, especially in the sand, I should be the one who select the right gear
Jeepnomad
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[quote=matts;41764]Do you know what your differential ratio is it will be something like 3.26 or 4.1 or 4.86? And could you tell us the tyre size (17in is the rim size) it will look something like 315/70/17 or 32/12.5/17.

The tyre says 315/70/17 M+5. To be honest i really dont know the differential ratio..... is there any way to find out?

Thanks for helping

Cheers
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matts
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Yep, you can find out either by putting your VIN number into this website, which will tell you what it came with from the factory, but it might have been changed.

http://jeep.custhelp.com/app/jeep/eqlis ... l/session/

Or you can follow the method described here which will definitely give you the correct answer:

http://www.jeepforum.com/forum/f96/want ... e-1074407/

For many other JK questions this page is very useful

http://www.jeepforum.com/forum/f96/jk-f ... s-1074059/

But to give an idea, my car has the same tyre size as you, with a 4.1 diff ratio, but is a manual so it has a slightly different final drive ratio to your auto. I drive mostly in first/second gear in 4H, because of the tyre size 2nd gear goes quite a long way but if you are not going fast enough there is not enough power in second to accelerate quickly.

I only really use 4L if i'm stuck, descending a long steep slope, or recovering someone else. Hope that helps, best thing is to get out there and experiment, see what works for you.
Zorro
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Jeepnomad;41744 wrote:Hi

After driving a Pajero for the last 10 years finally bought a Jeep Sahara Unlimited Automatic 2007 model - came with a 3 inch lift kit, Mopar air intake, 17 inch Cooper tyres, rack and pinion done, aftermarket exhaust etc (this is my first Jeep so not sure what more was done to it)

Heard about the problems with JK engine overheating and installed a hack job transmission cooler in series with my existing cooler.

The question is

What is the best gear to drive in the following situations

1 Short (say 40-50 ft) but steep incline - have to go over the lip and dont want the car to jump into higher gears and lose torque - i.e need short burst of maximum torque

2 Long but not so steep incline and want to go as far as possible up the dune

In the Pajero i could control and shift as i wanted with the Steptronic - but how do i handle it in an Automatic Jeep.

What is the difference between driving 4H in gear 2 vs driving 4L in D - any recommendations
Finally there is a switch that says O/D off - should i activate it?

Any suggestions and comments welcome

Tks

Jeepnomad
Hi Jeepnomad,

Congrats on ur new ride.

Let me share my point of view in regard of your first 2 questions. The beauty of the desert is that there are no 2 dunes alike and sand consistency is not the same everywhere. (i.e. what works for a dune may not work for an other)

Said that, I believe recommending a gear for any of the situations you have mentioned above is pointless and of no help as there are just too many factors to consider. However, it will most probably be either first or second gear (4H), unless it’s a dune like Big Red where people go 1km far to take speed and climb it.

As Orsomucca said rather than looking at theory, the Best and Only solution to your questions is to drive!

In 4H you stress less the powertrain compared to 4L. Again it depends on the situation and what you are doing.

Cheers
Jeepnomad
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matts;41776 wrote:Yep, you can find out either by putting your VIN number into this website, which will tell you what it came with from the factory, but it might have been changed.

http://jeep.custhelp.com/app/jeep/eqlis ... l/session/

Or you can follow the method described here which will definitely give you the correct answer:

http://www.jeepforum.com/forum/f96/want ... e-1074407/

For many other JK questions this page is very useful

http://www.jeepforum.com/forum/f96/jk-f ... s-1074059/

But to give an idea, my car has the same tyre size as you, with a 4.1 diff ratio, but is a manual so it has a slightly different final drive ratio to your auto. I drive mostly in first/second gear in 4H, because of the tyre size 2nd gear goes quite a long way but if you are not going fast enough there is not enough power in second to accelerate quickly.

I only really use 4L if i'm stuck, descending a long steep slope, or recovering someone else. Hope that helps, best thing is to get out there and experiment, see what works for you.
Thanks Matt - will check it out....
Jeepnomad
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Thanks Zorro...
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