2018 JLU Rubicon - Pitch and roll angles

[alkapin]

Any ideas what are the critical (about to flip over) values for the stock JLU Rubicon?

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[alkapin]

Anyone can comments on the critical angles here? Would love to understand when entering the danger territory.

Thanks!

 

[coukos34]

Bump

I’m interested too. I hit 22 degrees roll last week (mild I know), but made me wonder how far you’d have to go to start tipping

 

[JB3]

I've done 35 for pitch and still felt well within the limits. 24-25 in the roll starts to get more of a reaction for me.

 

[Jeep4Life0112]

If you hit 180 you have gone too far

 

[alkapin]

If you hit 180 you have gone too far

Must be talking from the personal experience?

 

[Zazoh]

I don't know the answer, but would think it would be a combination of load distribution in the jeep combined with suspension compression / flex, pitch, roll a bunch of things all combined.

My F150 would tell me which tire (s) were spinning, I think that was more useful.

 

[Firecracker18]

It's an interesting question nonetheless. It would have been nice if the gage turned different shades like the more pitch or roll it would show a yellow (caution) or red (danger) zones. I understand how you have it loaded, tire pressure, etc matter but just take a stock Jeep with the driver and they could have come up with something more meaningful.

I remember in my TJ coming across a "small" mound - we're talking no higher than say 1 1/2 2 door Jeeps long and just as I was about to crest the front end lifted off the ground. Totally caught me off guard. How the heck was this thing so steep? I backed off throttle immediately and the TJ sat back down and I backed down that "small" mound. Ha ha!

I also remember as a passenger in my brother's CJ-7 going up this steep mountain but it didn't seem "too" steep and the front end lifted as we were pretty far up it. It did not settle back down though and began a slight rock. My brother told me to stay perfectly still - DON'T MOVE! We made it back down and stopped for the day. Scared the hacked out of us both and that Jeep has been through some of the toughest terrain there is.

So yes, valid question.

 

[GRAK]

It's an interesting question nonetheless. It would have been nice if the gage turned different shades like the more pitch or roll it would show a yellow (caution) or red (danger) zones. I understand how you have it loaded, tire pressure, etc matter but just take a stock Jeep with the driver and they could have come up with something more meaningful.

I remember in my TJ coming across a "small" mound - we're talking no higher than say 1 1/2 2 door Jeeps long and just as I was about to crest the front end lifted off the ground. Totally caught me off guard. How the heck was this thing so steep? I backed off throttle immediately and the TJ sat back down and I backed down that "small" mound. Ha ha!

I also remember as a passenger in my brother's CJ-7 going up this steep mountain but it didn't seem "too" steep and the front end lifted as we were pretty far up it. It did not settle back down though and began a slight rock. My brother told me to stay perfectly still - DON'T MOVE! We made it back down and stopped for the day. Scared the hacked out of us both and that Jeep has been through some of the toughest terrain there is.

So yes, valid question.

Agreed, would like to know general Danger Zone numbers for a 2 door. Was 26° on the display yesterday and made me wonder.

 

[Jaym]

At 30 pitch I definitely feel the weight shift off the front axle.

 

[MNWrangx2]

I'm curious on this too, although I get the "it depends" part. I asked this same question the first time I rolled >20 degrees in my JL-R. On pitch that doesn't both me as much and have been at 30+ several times (up & down) and felt just fine, although club members have rolled backwards (on different places than where I was; unknown initial angle). Roll however is much scarier to me at 22+ degrees (especially leaning towards a cliff edge), and I was feeling uneasy in the mud on 15 psi 33's yesterday at 25 degrees next to a rock. My personal opinion one should stay in the low 30s or less on both to avoid the 'it depends' factors as you approach the no-go 45+(?), but do NOT rely on me as I'm still a noob. Also of course, go slow! Something like "go as slow as you can, as fast as you need to".

 

[Matstery]

It is a physical fact that any object will tip over when its center of gravity gets outside its base of support. A jeep's base of support is easy to measure -- it is simply the vehicle's track width. The center of gravity, however, is not so easy to measure. A stock, static vehicle by itself will have a very precisely located CoG, but fuel tank levels, lift kits, mounted accessories, and occupants have a huge effect on the dynamic CoG -- especially the number, placement and weight of occupants. For instance, a single occupant in the driver's seat will raise the CoG of the vehicle slightly and move it a little to the left. A driver plus two passengers in the right front and right rear will raise the CoG even more, but move it slightly to the right. Yes, placing two occupants on the uphill side of your vehicle will help significantly.

As long as you keep your CoG over your track width your are in good shape, provided no additional force is applied (like momentum) which would swing your CoG past the tipping point.

In the Wrangler diagram below, if you assume the CoG is at the center of the spare tire mount (probably not far off if there are four occupants), I calculate the rollover angle would be roughly 40-degrees.

 

[Maverick909]

alot of factors to take in for consideration. like others have said. load, tire PSI, fuel, etc. ive takening my sport wrangler ( i do have rubicon take off suspension) without the swaybar disconnected to 24 degree roll with my 135lb rooftop tent and 80lbish rack system rack might be less weight than that. ill tell you that was really starting to get uncomfortable. as for pitch going down ive seen 30 facing down and that wasnt feeling good. had tires at 20 psi and 4 of us in the jeep at the time and no RTT on. but i have done the whole broken arrow trail in az with my RTT on and tires at 22psi. even manged the steps with minor scraping

 

[alkapin]

It is a physical fact that any object will tip over when its center of gravity gets outside its base of support. A jeep's base of support is easy to measure -- it is simply the vehicle's track width. The center of gravity, however, is not so easy to measure. A stock, static vehicle by itself will have a very precisely located CoG, but fuel tank levels, lift kits, mounted accessories, and occupants have a huge effect on the dynamic CoG -- especially the number, placement and weight of occupants. For instance, a single occupant in the driver's seat will raise the CoG of the vehicle slightly and move it a little to the left. A driver plus two passengers in the right front and right rear will raise the CoG even more, but move it slightly to the right. Yes, placing two occupants on the uphill side of your vehicle will help significantly.

As long as you keep your CoG over your track width your are in good shape, provided no additional force is applied (like momentum) which would swing your CoG past the tipping point.

In the Wrangler diagram below, if you assume the CoG is at the center of the spare tire mount (probably not far off if there are four occupants), I calculate the rollover angle would be roughly 40-degrees.

Nice summary! Thanks.

I personally have been at 30 degrees multiple times and it doesn't feel nice Especially with 4.5 inch lift and RTT. But I have wider track than stock which help for sure.

What would be great is to put a trip loaded Jeep on some kind of platform that slowly tilts to the side and have a cable attached to the roll bar thru an open window to prevent a fall and actually measure your own tipping angle. Maybe use a tow trailer and a fork-lift? Anyone have access to these to do such experiment on their setup?

 

[Matstery]

Nice summary! Thanks.

I personally have been at 30 degrees multiple times and it doesn't feel nice Especially with 4.5 inch lift and RTT. But I have wider track than stock which help for sure.

What would be great is to put a trip loaded Jeep on some kind of platform that slowly tilts to the side and have a cable attached to the roll bar thru an open window to prevent a fall and actually measure your own tipping angle. Maybe use a tow trailer and a fork-lift? Anyone have access to these to do such experiment on their setup?

Yes, 30 degrees is the official "butt-puckering angle".

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