puddlepirate-xj

Well this is post number three and with every modded jeep pic i see and all the different ways to modify these xj's i think i havr caught the bug. i was considering a 3 inch lift from RC or zone but after reading the low COG sticky i see genius to say the least. it makes perfect sense to keep your center of gravity as low as possible while maintaining capability. im not looking to run 37 inch swampers but i think 32s on a 2 inch lift with some mild trimming i think is an awesome concept. or even 33s. any ideas on this? I dont need a super jacked jeep and they look GREAT lifted but im in the market for functionality and getting my baby to take me everywhere the 3inch looks great and provides a good base to start with. Such as arms shocks and such and a 2 inch from my understandin would be a more part by part basis. Which is fine but I was just curious of any thoughts or ideas about this? I love my xj its only got 118k miles on it so its gonna be around a while and I have wheeled it since day one but I've just never had the time or money to build it and now I do and I want to do it right

Atmos

1. there's a difference between having a low center of gravity and a low cog built rig. a 2" lift on 32's isn't really relevant. it's just a regular jeep. 2 - 5" of lift is great. go for it

2. the main thing you should take away from that sticky is that you don't need 6 or 8 inches of lift to have a lot of "flex." very few of us on here will ever have a purpose built low cog rig. just understand that theres minimal correlation between lift height and how much suspension travel (flex) you can have. and there's no reason to lift your jeep to the moon

Ianf406

I don't know about no reason.. I'de rather not drag my oil pan through the mud/snow... low-cog vs a higher lifted one, assuming you have the same tires, everything other than the pumpkin will have more ground clearance.

Other than that, I agree with you. Down travel won't be significantly impacted by lift height and keeping your center of gravity a few inches lower will certainly help in some situations.

Michael952

Skid it up. Would rather drag a skid than smash my roof

Atmos

actually that's the sole reason. apparently to be successful in mud you need to have a really tall lift. which is fine. just have axles and tires to match. there's a couple really sick mudders on this forum, but for the guy running 10" of lift on 35's and stock axles... I guess that's the equivalent of full retard

we could debate it all day but none of it will be relevant to the OP who is just talking about a basic BB and tires

zeecherokeeman

i got 2 inch lift with 31'' tires and it works fine

Tom95YJ

I don't consider my XJ LCOG but it does have a smaller lift and fairly large tires. 3.5" on 35's with. Plenty of trimming bump stopping and shocks long enough to allow me to fully take advantage of my upper and lower adjustable arms. And make me debate getting limiting straps.

Ianf406

And I would rather not have my engine suck in water when I cross a creek.

A skid plate would only make the situation worse. You can push your pumpkin through mud or snow if you have contact with the ground. Good luck shoving your entire engine through there. Wonder how many winners of mud bogs are in a "low Cog" rig?

It really matters what your Jeeps primary function is going to be. If it is going to be primarily a mudder... there is no reason to worry about tipping and there is reason to worry about ground clearance. If you are into the Jeepspeed/desert racing type scenario, up travel is extremely important. If you are going to going through a lot of off camber situations/huge rocks, then yes, having a low COG will help you out.

If you were really worried about having a tip-proof rig, You should just get a JK... They are 74" (vs our 67.9") wide and with the soft top/solid frame have a much lower COG in relation to their height.

As far as low COG, the main advantage is of course tipping point. Physics tells us the relationship between the COG and the point on the ground (tipping point) remains the same if the geometry of the objects stays the same. My Cherokee is 67.9" wide and 64" tall. So by raising it 6.5" (Lift) the COG moves up roughly 10%. Factoring in the tires, stock on mine were 28x9x15 (215x75x15) going up to a 35x12.5.16, moves me up another 7 inches or 11%. So my height and COG are now 21% higher than stock. Which means the Low COG (assuming no lift) has and 11% higher than stock. Include the extra width of the tires/backspacing I'll estimate you sit 6" wider total which equals ~9% of your width. You could easily throw on some spacers or wider axles to compensate for the extra height.

This gives a "Low Cog" no lift on 35" XJ about a 2% off set (for the worse) tipping point and the "lifted" (6.5") a 12% offset (also for the worse). Physics also tells us that a tipping point of the object occurs when the center of mass (COG) is dead center with the point of contact. While it is tricky to calculate the C of M on an XJ as it is not of a uniform density, assuming the lifted XJ had a uniform density (impossible to calculate actual density right now), the center of gravity would be located at 36.5" wide and 35.5" tall. The formula to calculate tipping point is simply as follows: 35.5/36.5= .973 Plug that into a Inverse tangent calculator (Arctan(X) and you get 44degrees. a+ 44degrees= 90 degrees. A (tipping point) would be 46 degrees (again assuming uniform density) Do the same for the "Low Cog" and you get a tipping point of 49 Degrees.
Obviously the density is going to be in a lower location in the object and thus the tipping point will be slightly greater than 46/49 degrees in a perfect world but the difference between the two is only 3 degrees...

Sorry- felt like doing some math on it out of curiousity lol- not trying to be argumentative.

dynasty_v6

Not to be a jerk but going from a 28 to 35 inch tire does not move you up 7 inches...

Ianf406

I know during the Army rough terrain course, we were told the Humvee (84" wide/72" tall) had a tipping point of 45 degrees... doing the math you get a tipping point of ~50 degrees and that is also not taking density into account. So taking how the Army is on everything (assumes we will always push the limit) even not accounting for tire compression/coil compression/density etc., it's not too far off.

Ianf406

Lmfao totally messed that up.
You're correct... 3.5".
*Edit* Still puts them very close to 3 degrees apart. And that is IF the "low Cog" has no lift on 35s. Width might be a little off as well- Just going off stock specs and making a quick guess at bonus from wider tires. The point remains the same though- It is not as huge of a difference as the low- COG guys make it seem.

Ianf406

http://www.jeepaholics.com/tech/cog/#_Toc535118710- There is a link to get your exact center of gravity and Roll-Over angle... looks like a lot of work lol.

Sorry to derail your post OP. 32"s on a 2" is entirely possible and would not require a whole lot of other parts other than gears. Once you start going above 3", you have to start replacing more stuff.

Atmos

I skim read your novel and it looks like you're arguing a point to no one disagreeing with you. just take it easy man

Tom95YJ

X2 get off the couch and go wheeling.

Ianf406

I was not arguing at all. Well a little bit lol. It is a common point made on the forum... That if you lift it high, you will tip over. Pretty much on a daily basis. I just find it interesting that the point at which a xj lifted 6.5 inches on 35s tips vs no lift and 35s is aprox 3degrees...very insignificant. Ide rather have the height.