Rubicon 4-Low Past 30mph W/6 Speed Manual

ToxicBanana

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I was trying to make it up a steep sand dune in 4Low 4th gear with lockers engaged, I was limited at 30mph when I was around 4k RPMs, this presented an issue as the governor is aggressive enough when it throttles you that I can potentially lose too much momentum and not complete the dune. I am still not sure if I was limited to 30mph because of the lockers or not (I didn't think about that as a possibility when I was there).

I choose not to try doing the dune in 4High 1st gear which is 29mph at max RPM (6-6.5k)
I did try 2nd in 4High but try after try 2nd gear seems to be too high causing me to lose power, bog down and have to retry.

in 4Low find 30MPH is ok, 35mph would have been better, my biggest issue was the engine cutting power too aggressively when the governor kicked in.

I have a few different options I can think of and would like your opinions.

1) Maybe the lockers are what caused the 30mph governor to kick in, assuming its safe to be in 4L at 35mph in very soft sand, then my solution would be some locker bypasses where I can engage them without the Jeep knowing they are activated or simply not use the lockers.

2) Assuming it's safe to be in 4L at 35mph in very soft sand, I could have a jeep programmer change the size of the tire down in such a way that it would think I am going slow enough in 4th in 4Low that the governor won't trigger

3) With 4high 1st gear with 35" tires and RPM red line I would achieve about 33mph which should be enough, bonus would be adding a locker bypass assuming again its safe to do so at that speed.

4) Just don't do it

How fast can you go in soft sand in 4Low?
How bad is it to push your car to redline (about 6-6.5k on this Jeep)?





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RockyMtnHigh

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First thing I've got to ask is what tire pressure were you running at?

Here's a clip from the owners manual. You shouldn't exceed 25 MPH in 4L
upload_2019-2-28_8-41-8.png
 
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ToxicBanana

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I was able to make it up the sand dune, but I wasn’t able to make it up the hill in this picture, the moment the governor kicked in I was screwed.

DC1C8061-1096-4BA3-8DCE-850E31A7429D.jpeg
 

RockyMtnHigh

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Honestly I've gone down as low as 8psi on the dunes. In fine sand I don't think 4 low really helps, just keep it in 4 high and punch it. Momentum is your best friend in sand dunes
 
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ToxicBanana

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I have a 6speed, in 2nd I lose momentum, in 1st gear I would have to be redlining the entire time, which is an option if that's safe.
This is why I was doing it in 4low as the gearing just lined up great. 3rd to start rolling and 4th at 30-35mph in the powerband
 

RockyMtnHigh

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I've also got the 6 speed. Shifting mid-climb is a no go. In my TJ, also manual, I got some speed and shifted into second just before the bottom of the hill so I didn't lose momentum. I know the gearing can make it difficult, but 4 low isn't the way to go, it's not rated for over 25 mph
 
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ToxicBanana

ToxicBanana

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That's disappointing because if 4low could do 35mph it would be great as its so much better compared to 1st-2nd in 4 high.

Thanks for the help.
 
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ToxicBanana

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The big take away from this is 4Low is a no go, I will see if I can make it work in 4High

"Have you looked into a tazer so you can have lockers in 4H? I wouldn’t recommend driving it like you’re describing in 4l.

Brett"
I did see the Tazer, the ability to use Lockers in 4high for sand use seems very valuable.

Thanks for the help everyone!
 

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Maybe 4:88 or 5:13 gears? Might make 2nd in 4h a sweet spot for your dune runs.
 

nerubi

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What's an owners manual? Is that the person that owns a manual transmission Jeep?
 
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ToxicBanana

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Maybe 4:88 or 5:13 gears? Might make 2nd in 4h a sweet spot for your dune runs.
I did think about 35" with 5.13 gears, this would put 2nd gear closer to the sweet spot.
 
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I was trying to make it up a steep sand dune in 4Low 4th gear with lockers engaged, I was limited at 30mph when I was around 4k RPMs, this presented an issue as the governor is aggressive enough when it throttles you that I can potentially lose too much momentum and not complete the dune. I am still not sure if I was limited to 30mph because of the lockers or not (I didn't think about that as a possibility when I was there).

I choose not to try doing the dune in 4High 1st gear which is 29mph at max RPM (6-6.5k)
I did try 2nd in 4High but try after try 2nd gear seems to be too high causing me to lose power, bog down and have to retry.

in 4Low find 30MPH is ok, 35mph would have been better, my biggest issue was the engine cutting power too aggressively when the governor kicked in.

I have a few different options I can think of and would like your opinions.

1) Maybe the lockers are what caused the 30mph governor to kick in, assuming its safe to be in 4L at 35mph in very soft sand, then my solution would be some locker bypasses where I can engage them without the Jeep knowing they are activated or simply not use the lockers.

2) Assuming it's safe to be in 4L at 35mph in very soft sand, I could have a jeep programmer change the size of the tire down in such a way that it would think I am going slow enough in 4th in 4Low that the governor won't trigger

3) With 4high 1st gear with 35" tires and RPM red line I would achieve about 33mph which should be enough, bonus would be adding a locker bypass assuming again its safe to do so at that speed.

4) Just don't do it

How fast can you go in soft sand in 4Low?
How bad is it to push your car to redline (about 6-6.5k on this Jeep)?
This is what I did, lockers in 2wd, 4 h or 4l no speed limitation
30A06596-4C75-4827-8E11-1CD1628FBB46.jpeg
D458B9C8-A7F4-44F5-9F3F-EA0FD865B804.jpeg
 

ZEN357

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I agree with RockyMtnHigh, momentum is you best best but have you looked into tuning your vehicle to disable the governor?
 

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