2 door vs 4 door flex / RTI score

Intense

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New guy and saw a spec table. Is it true the 2dr has a higher score than the 4 dr?
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rynomar

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Yes, RTI scores are based off of the wheelbase of the vehicle being compared to the distance traveled up the ramp (distance traveled divided by wheelbase x 1000, or (70.28/100.4)x1000= 700.
The degree of ramps varies, but 20 degrees is commonly used, but be careful comparing numbers from different ramps.
Calculations based on Badlands spec sheet:
2 door (100.4” wheelbase)
RTI= 700 (disco)
Distance traveled up ramp=70.28”
Vertical Increase= 24.04”

4 door (116.1” wheelbase)
RTI= 620 (disco)
Distance traveled up ramp =71.99”
Vertical Increase=24.62”

A score of 1,000 would mean the vehicle travels up the ramp a distance equal to its wheelbase. Longer wheelbases would have to go higher and shorter wheelbases not as far.
I personally think it is a nice reference, but in the real world there are so many other factors that play into what works best and that often changes from one challenge to another.
 

rynomar

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I think it is really cool to see that the difference between connected sway bar and disconnected works out to about 5” on the 2door and 4.8” on the 4 door. That is a huge difference!
 
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I think it is really cool to see that the difference between connected sway bar and disconnected works out to about 5” on the 2door and 4.8” on the 4 door. That is a huge difference!
I really appreciate the thorough explanation. So essentially, if I’m looking at this right, though the score is different, the amount of flex difference is insignificant?
 

rynomar

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I really appreciate the thorough explanation. So essentially, if I’m looking at this right, though the score is different, the amount of flex difference is insignificant?
I would say that the amount of vertical travel between the 2 door and 4 door is comparable.
What are your concerns?
 
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I would say that the amount of vertical travel between the 2 door and 4 door is comparable.
What are your concerns?
Just understanding it more to be able to compare capability.

I’m still confused as to what the number indicates then. I just read a couple of articles. I see the math. I understand the concept of traveling up the ramp up until the next tire starts to leave the ground. But... if the 2&4 dr are essentially the same travel in the front wheel, why is it that the number being higher means it’s able to traverse rough terrain better due to keeping tire contact on the ground more? Isn’t the distance traveled up the indicator?
 
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rynomar

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I think that is exactly where the RTI shows that it isn’t a perfect tool for measuring capability. Articulation allows for more contact with the ground, which provides traction and stability.
Larger tires (additional ground clearance), lockers, skid plates, and proper gearing are all things that should be added into the equation when considering capability and all of it depends on what kind of driving you plan to do.
The recent Broncos from Moab and the Rubiconhave some really good footage of the 2 door and 4 door on different obstacles and each had an advantage/disadvantage depending on what it was, but were nonetheless capable.
A Jeep Wrangler will have more articulation than a Bronco and in some situations that would be an advantage, but the Broncos IFS has many advantages as well.
 

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Just understanding it more to be able to compare capability.

I’m still confused as to what the number indicates then. I just read a couple of articles. I see the math. I understand the concept of traveling up the ramp up until the the next tire starts to leave the ground. But... if the 2&4 dr are essentially the same travel in the front wheel, why is it that the number being higher means it’s able to traverse rough terrain better due to keeping tire contact on the ground more? Isn’t the distance traveled up the indicator?

Not an expert, but I think that since the RTI score incorporates wheelbase one must consider that a shorter wheelbase results in a higher score. In other words, while the 2 door and 4 door both get about the same distance up the ramp and therefore have similar articulation, the shorter wheelbase of the 2 door nets a higher score. If you compare the specs, you'll also find that the two door has a better breakover angle. Ergo, the two door will be slightly more capable off-road than the 4 door and thus the higher RTI.
 
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Not an expert, but I think that since the RTI score incorporates wheelbase one must consider that a shorter wheelbase results in a higher score. In other words, while the 2 door and 4 door both get about the same distance up the ramp and therefore have similar articulation, the shorter wheelbase of the 2 door nets a higher score. If you compare the specs, you'll also find that the two door has a better breakover angle. Ergo, the two door will be slightly more capable off-road than the 4 door and thus the higher RTI.
It just throws me off calling it Ramp Travel Index then. lol

I think you’re right. That’s likely what they’re trying to convey despite the acronym and also wheel base being a factor in the formula.
 

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Just understanding it more to be able to compare capability.

I’m still confused as to what the number indicates then. I just read a couple of articles. I see the math. I understand the concept of traveling up the ramp up until the next tire starts to leave the ground. But... if the 2&4 dr are essentially the same travel in the front wheel, why is it that the number being higher means it’s able to traverse rough terrain better due to keeping tire contact on the ground more? Isn’t the distance traveled up the indicator?
The thought is that as long as you can keep your tires on the ground you keep traction and stability. If you can get your rear tires to the obstacle before coming off the ground it is a perfect score. In the real world that could be a rock or rut but when you watch the tests or are doing it yourself once that tire comes up it is really tippy. As others have said this is just one metric. Climb a steep long hill and that lower RTI score because of a long wheelbase is null and void because it is way more stable.
 

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My 2-door came in dead last on the RTI ramp at SuperCel Colorado, beat by the 4-doors (and of course all the solid axle Early Broncos). But mine is a Base-non-Squatch and the 4-doors were Badlands and First Editions with swaybar disconnects and lockers :)
 
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