zstairlessone

I think, and as usual am probably wrong, that the whole issue with roll center and COG is to keep the COG close to the roll center so the mass has less effect on the body's position (imagine a short handled wrench vs a long handled wrench). Solid axle vehicles with the type suspension found on a JK should roll around the centerline of the jeep left to right and on level with the imaginary intersection of the lower control arms (where above the ground this happens). Putting long or short arms should not affect either the COG or roll center.

And I don't think unsprung weight affects COG or roll center when you are talking about vehicle dynamics, but it does have an effect on your suspensions ability to control the axles.

Long arms, again just my thoughts, allow for less force to be transmitted back through the frame and bushings due to a lesser angle and should allow for less binding giving the opportunity to utilize longer travel components.

Or they could just provide bragging rights, in any case I'm certainly not an expert....

BeachJK

Pretty much, imagine your pushing a wheel barrel. Your the Jeep and the handles are the control arms. Pushing with your hand low at your hips. Easy and low strain. Now try hold the handles up by your ribs(CA steeper angle)and pushing gets harder and more straining.

TheDirtman

You are correct and I missed that the longer wheel base would provide more stability. That would make 3 things that the 4 door is better at. Your examples you give are based on that longer wheel base. Oversteer is a product of suspension geometry not wheel base.

mhockey9090

Like Dirtman said and this is not the first time I've heard of it. The stretch would not make it to the same length a 4 door is. Its enough of a stretch to make the vehicle wheel in more places now because we have better approach or decline angles. Also not get hung up on as much as a 4 door would have because our wheel base is still shorter. Plus we are still a lighter vehicle, depending on how much is carried additionally of course.

2 Door 95.4 inches (so an 11 inch stretch would make it a total of 106.4 inches, Just shy of 10 inches shorter of a 4 door)
4 Door 116 inches

I don't think I've ever heard of a vehicle than can out wheel every other one out there. Theres pros and cons to each unique build and some have harder times than others on an obstacle. Picking the right line is also a huge part of this, but each Jeep is different. To each their own on their build.

and to be honest I wanted a 4 door when I was shopping, but didn't want to spend the extra $3k for it. I rarely have more than one passenger, so my back seat has been sitting in the garage collecting more dust than anything. I just want to make my vehicle a better off road machine and go up some of these obstacles that 4 doors have an easier time on, but have those qualities like Dairyman mentioned.

JKZinger

Long arms give you a better highway ride when you have a lift over 3" and also control your axles much better eliminating things like axle slap causing driveshafts to move laterally and hit skids. They do not increase articulation or flex, they just keep things closer to the same location as they were when the Jeep was stock with OEM control arms.

GJeep

This claim may mislead readers, as it’s simply not true.

A. Wheelbase
Wheelbase is an important factor in oversteer, because oversteer is influenced by the wheelbase/track ratio.
As this ratio is the main difference between a 2-dr and a 4-dr, there’s also a considerable difference between the two in oversteer, and in overall directional stability & handling.

B. Suspension geometry
Saying that “oversteer is a product of suspension geometry” ignores a whole list of factors in oversteer.
More factors are, for instance -
Suspension dynamics
Rear, front or 4x4 drive
Front/rear weight distribution
Frame dynamics (rigidity/flexibility)
Tire type
Tire pressure
Braking force balance between front and rear

Offroad, in certain circumstances, a 2-dr is easier to roll over to the side, and not only backwards or forward.

T&ERun

GJeep, not sure why you are driving a Jeep with all that you have said here. Sounds like a truck would be better for what you're after. A truck will have a longer wheelbase that should climb better, be more stable on muddy hills, and be more reliable on the street with much less oversteer.

TheDirtman

Yes, all those things can affect how the rear end slides around (or doesn't) but on a JK, off road there really is not an issue as most don't do drift racing with them. I was too general with my term. And again you go way off tangent when talking about the JK in the real world. Don't forget to add coil rates, caster, camber, tire sidewall stiffness, shocks valving, torsion bar rates, and the biggest issue which is speed to make your list look longer. Wheel base is generally not used to compute underrate/oversteer in formulas.

Whats wrong with oversteer? I would rather have oversteer then understeer. I guess it is a preference of the driver and how they interact with their vehicle. You can come up with good and bad for both but really I don't see an issue with it off road with a JK if you know your jeep and how it handles.

IF you are just going to make stuff up without specifics, I guess you could also say off road in certain circumstances a 4 door is easier to roll over sideways. You could also say that they explode in certain circumstances more then a 2 door.

You don't like this back and forth but if you would have just admitted that you were wrong with your comment about adding weight lowers the center of gravity, none of this would come up. Saying you were referring to the "body COG" is bs as nobody even mentioned such a thing until you did about 10 posts after your incorrect statement.

And for the record I have a 2 door and a 4 door JK and the 2 door is better for everyday general wheeling and rock crawling, the JKU is better for overland expeditions and camping trips because it is off road capable and can carry the extra gear.

zstairlessone

I think that oversteer is a term used to describe the back end being loose into a curve under power and under steer means the front pushes in that turn/curve. You can tune this with suspension
Edit: design (tune with suspension design)

GJeep

It was in the real world, and much more than once, on slippery, twisting mountainous trails, that my Jeep skidded a lot on straight sections and oversteered in turns, at speeds which could almost be called slow motion.
There must be quite a few on this forum, who’s Jeeps oversteered when given the chance.
By saying that “most don't do drift racing with them” or “you go way off tangent when talking about the JK in the real world”, you brush off part of the offroading reality and basic Jeep handling.
A 2-dr skids more, and oversteers more (and somewhat more suddenly), than a 4-dr.

Jeeps happen to drive on roads too… How about an emergency maneuver on a very slippery road?
This reminds me… Some years ago, a heavy rain started -- the first rain after a long dry & dusty season. Moments later I was on a 2 lane tight ‘S’ (in the city). I know how slippery such a first rain is, so I was slow, at about 8 mph. Did the tight left, then right, and the rear oversteered, at slow motion, about 40 degrees. Luckily, there was no car on the opposite lane, so I just straightened.

So, this -- “you go way off tangent when talking about the JK in the real world”, might suggest lack of sincerity or lack of varied driving experience.

Did I say that oversteer is bad? Did I say that oversteer is an issue?
I prefer oversteer over neutral steer, and I don’t like understeer.
I said that a 2-dr oversteers more, and has less directional stability than a 4-dr – That’s a fact.

Again, I see low language and arguing for arguing sake… and you’re wrong again.
Of course, CG (vs roll center) refers to the CG of the sprung weight. So I said ‘body’ and didn’t bother to list everything that’s solidly attached to it or it is attached to... my point was clear, and the fact remains: Weight which is added below the CG, lowers the CG.