Xtreme Recon math doesn't add up... Can anyone set the record straight?

YukonCornelius

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So while I wait for even a VON, I'm still obsessed with reading about my future vehicle. Here's the problem - I can't make any sense of Jeep's claimed Xtreme Recon stats on the 392... standard Rubi, maybe. But not on the 392. The numbers don't add up.

Here's what I mean. The "35's" (315/70x17's) are 1.7" taller than the Stock 33's. At center, that creates .85" additional overall height.
So with just .85 inch increase, how does the 392 gain 1.1 inch fording depth, 2.6 inch additional ground clearance, and 4.1 degrees greater breakover. I'm too lazy to do the angle math, but I'm pretty sure .85 will give around two degree.

And this is all assuming the 392 KEEPS the standard 2" lift and doesn't drop to the Recon 1.5

Anyways... anyone out there that could explain this to me?


Approach angle: 47.4 degrees (up from 44.5)
Breakover angle: 26.7 degrees (up from 22.6)
Departure angle: 40.4 degrees (up from 37.5)
Ground clearance: 12.9 inches (up from 10.3)
Water fording: 33.6 inches (up from 32.5)

PS STILL glad I waited for the recon package :) regardless.
 
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thats an easy one, first you have to find out the definition of ground clearance. We think it means if we built a brick wall that could not be knocked over and made it 12.8 (ground clearance is 12.9 on a 392) inches tall and left two cut outs for the tires 12.4 inches wide for each tire then we could drive right over it as long as the tires were lined up properly with the cut outs? Right?

NO!!

Pictured is my 392 with 35 inch tires which are true 35's not 315 metric which are 34.4 and what is going to happen if I drive it over the brick wall in the scenarion I stated above? Damage!!

Sorry for the bad angle shot but would you agree that the 392 does not have 12.9 inches of ground clearance according to the definition the average consumer thinks it means now after looking at the pic? Dont rack your brain anymore over it.

Think about this instead, I placed an order for a Recon and then went home and did the match and canceled it the next morning. I got a VIN in less than two days so not sure what the deal is there.

I run larger than 315s already and run an aftermarket wheel and am changing to 37's so there is no advantage there for me. It is very possible that the 4.56 might improve fuel economy for a 35 but I use 4wd for off road and snow equally.

The Recon will be an extremely capable off-road vehicle but for me the price of the package is more than I could re-gear for and I think the 4.56 is slightly too much gear but more important is what is going to happen when I want to run 40-50 mph in 4wd with a 110:1 transfer case?

Calculate that because that is reality, ground clearance is always BS

If you are a primarily off road guy and a very slow crawler then the Recon will be perfect.
 

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Thanks for the pic, @Smess. I'm surprised that it's only 9.5 at the shock mounts. I'm pretty sure that Jeep is measuring the same way Ford is for the Bronco - in fact, there was a Jeep released picture to show how the difference in IFS versus SFA can make in "useful" ground clearance - and that's either the pumpkin or transfer case, which is a pretty standard measurement. But regardless of the WHERE - I'm still trying to figure ANYWHERE Jeep could gain over 2" height on ANY measurement with a kit that only adds .85" overall height (on the 392)

Okay - so standard Rubi will get an additional half inch in suspension lift - so they might be closer on the standard Rubi. But nothing adds up on the 392 Recon kit. At first I was sort of excited that I had to get it... but now? Knowing I'd rather have 37's (after seeing everyone's posts here) I'm questioning "what am I really getting" that I want? Hinge reinforcement? Well, I could've saved $3400 and just got those like on my original order...
 
Thanks for the pic, @Smess. I'm surprised that it's only 9.5 at the shock mounts. I'm pretty sure that Jeep is measuring the same way Ford is for the Bronco - in fact, there was a Jeep released picture to show how the difference in IFS versus SFA can make in "useful" ground clearance - and that's either the pumpkin or transfer case, which is a pretty standard measurement. But regardless of the WHERE - I'm still trying to figure ANYWHERE Jeep could gain over 2" height on ANY measurement with a kit that only adds .85" overall height (on the 392)

Okay - so standard Rubi will get an additional half inch in suspension lift - so they might be closer on the standard Rubi. But nothing adds up on the 392 Recon kit. At first I was sort of excited that I had to get it... but now? Knowing I'd rather have 37's (after seeing everyone's posts here) I'm questioning "what am I really getting" that I want? Hinge reinforcement? Well, I could've saved $3400 and just got those like on my original order...
Gears will be worth it, I think the 3.73 is borderline for running a 37 but I only ran them for a couple weeks. Today the new 37's go on (Baja Boss MT) so I can talk more intelligently next week after a couple tanks of gas.
 
True! Forgot about 'dem gears!

Post pics when you get the new shoes on!!!
 
The bad new is looks like a re-gear is in the near future, which means the Recon 4.56 gear might be almost perfect
 

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Look‘n good! (y)
 
Look‘n good! (y)
thanks, this is getting more interesting. Once I made adjustments to the taser mini adjusting for the larger tires the tranny stopped shifting like when the JK's had the old minivan motor and we used to run 35's or 37's. stay tuned
 
thanks, this is getting more interesting. Once I made adjustments to the taser mini adjusting for the larger tires the tranny stopped shifting like when the JK's had the old minivan motor and we used to run 35's or 37's. stay tuned
The 392 is my first jeep automatic. That being said People report that the transmission "learns" and can be reset to relearn from what I read. No personal experience. Not sure if it continually learns and would "adjust" shift points over time or if it is just for a specified time and needs to be reset. If it continually adjust it should even get better with miles going to a change like 37" tires. "I" believe the 6.4 has plenty of Tq for 3.73 and 37" tires but if shift points were learned using a 33" tire the jeep would probably benefit from a reset. Like wise if it only relearns over a specified time and you switch say from stock 3.73 and 33" to 37 and 3.56 it probably would still benefit from a relearn.

From what little I have read on it the dealer can reset it and maybe using the J-scan app? Have not looked too far into it yet. Just a thought.
 
Haven’t used the taser before… does it have a “reset to factory “ setting to try? Stinks to have the issues but at least the only major issue would be the speedo calibration way off until you can sort it out…
 
thanks, this is getting more interesting. Once I made adjustments to the taser mini adjusting for the larger tires the tranny stopped shifting like when the JK's had the old minivan motor and we used to run 35's or 37's. stay tuned
Setting the Tazer for 37" tires did improve the shifting points of my vehicle and the gas mileage is roughly 15.139 mpg around town at 4500 feet where we only have 91 Octane available locally.
 
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thanks, this is getting more interesting. Once I made adjustments to the taser mini adjusting for the larger tires the tranny stopped shifting like when the JK's had the old minivan motor and we used to run 35's or 37's. stay tuned
Thank you for the info on the Tazer mini. I have read elsewhere that the Tazer mini would not work with the 392 motor.
I had a AEV for my JK and It allowed me to change a few things but nothing with the engine or transmission, tire height and gear ratio
I had changed the engine and transmission tune in my 18 Ford Raptor and had a tune for 91 octane and one for 93 octane. After I loaded the ture it was like driving a different truck, shift points were right on and a significant improvement on the dyno
 
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Thank you for the info on the Tazer mini. I have read elsewhere that the Tazer mini would not work with the 392 motor.
I had a AEV for my JK and It allowed me to change a few things but nothing with the engine or transmission, tire height and gear ratio
I had changed the engine and transmission tune in my 18 Ford Raptor and had a tune for 91 octane and one for 93 octane. After I loaded the ture it was like driving a different truck, shift points were right on and a significant improvement on the dyno
The Tazer Mini worked perfect on my 392! One of my best investments regardless if my initial intent was to only alter my speedo.

Aside from altering my tire size (to 35") it has many other features I found beneficial, but back to the subject...

I had roughly 3,000 miles on the 392 with slightly oversized tires before purchasing the Tazer. Referencing a separate post, the transmission may have compensated for the shift points as it 'learns', if so it was such an insignificant change I didn't notice.

To consider... if the system is so smart at learning why would it not figure out and display an accurate vehicle speed? At an 80mph dash reading I was actually doing about 7 miles an hour faster. With all the sensors on this vehicle to include the Jeep having 'learning' capabilities, it seems that this learning system would realize that there's larger tires on the vehicle. Especially since pretty much everyone puts larger tires on, if Jeep were to add Artificial Intelligence I'd think that'd be the first thing they'd have the AI look for...???
 
The Tazer Mini worked perfect on my 392! One of my best investments regardless if my initial intent was to only alter my speedo.

Aside from altering my tire size (to 35") it has many other features I found beneficial, but back to the subject...

I had roughly 3,000 miles on the 392 with slightly oversized tires before purchasing the Tazer. Referencing a separate post, the transmission may have compensated for the shift points as it 'learns', if so it was such an insignificant change I didn't notice.

To consider... if the system is so smart at learning why would it not figure out and display an accurate vehicle speed? At an 80mph dash reading I was actually doing about 7 miles an hour faster. With all the sensors on this vehicle to include the Jeep having 'learning' capabilities, it seems that this learning system would realize that there's larger tires on the vehicle. Especially since pretty much everyone puts larger tires on, if Jeep were to add Artificial Intelligence I'd think that'd be the first thing they'd have the AI look for...???
I think this is the same issue I had with my Raptor with out of the box tunes, there are certain Parameters that the factory program will not exceed such as the MPH being off by so many much. I did a trans tune to my Raptor and it was like night and day,and the octane and dyno tune made it a totally different truck, you were even able to set the steering wheel feedback from the factory set up.
I hope someone comes out with one soon, it was nice to have different driving modes to choose from. Hell even my wifes Grand Cherokee Overland has more choices than my Rubicon
I would think with this motor being out in so many different vehicles that someone would be jumping on the
opportunity to come up with a tune.

That is the one thing that I really enjoy with the Raptor is that you can truly feel the difference when you switch to a tune and especially a tune that was done on a dyno and you are still safe and not pushing the boundaries to the edge. When you select Sport Mode and get on it hard and you can get a solid second gear chirp out of it is worth it. Hopefully the Jeep will follow soon

 
The Tazer Mini worked perfect on my 392! One of my best investments regardless if my initial intent was to only alter my speedo.

Aside from altering my tire size (to 35") it has many other features I found beneficial, but back to the subject...

I had roughly 3,000 miles on the 392 with slightly oversized tires before purchasing the Tazer. Referencing a separate post, the transmission may have compensated for the shift points as it 'learns', if so it was such an insignificant change I didn't notice.

To consider... if the system is so smart at learning why would it not figure out and display an accurate vehicle speed? At an 80mph dash reading I was actually doing about 7 miles an hour faster. With all the sensors on this vehicle to include the Jeep having 'learning' capabilities, it seems that this learning system would realize that there's larger tires on the vehicle. Especially since pretty much everyone puts larger tires on, if Jeep were to add Artificial Intelligence I'd think that'd be the first thing they'd have the AI look for...???
The ability to brag about meeting CAFE standards and EPA fuel milage claims would be my bet.
 

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