Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

81 - 100 of 143 Posts

·
Administrator
Joined
·
17,026 Posts
Discussion Starter · #81 ·
Thus begins the slippery slope of which specs we choose to adhere to, and which we justify in our minds and choose to ignore.

I chose to ignore frontal area for several years because personally I'm OK with fudging a little, but ultimately fudging 40% over max spec just didn't seem wise to me. It's the main reason I quit towing our cargo trailer (42sq ft frontal area, 3500 pounds loaded) with our Jeeps and started using a truck. Some years we'd tow 100 times, some years as little as 50 times. Usually trips were only 20-200 miles, but sometimes over 1,000 miles.

Several times it was all good, until it wasn't all good. That's why I finally deemed it unwise to continue to disregard the max specs.

YMMV
 

·
Super Moderator
Joined
·
2,728 Posts
35-40 mph is not where frontal area is a problem. It’s in the 55-60 mph where the drag is significant.

I can’t remember my trailer’s exact frontal area, it’s somewhere in the 62-68 sq-ft range that I pull with a 60 sq-ft max rated vehicle. Coolant & trans temps are ok, only slightly elevated. It’s the engine oil temp that spikes 30-50 degrees above normal. as it works hard to drag that air at highway speeds

1/2 ton trucks are glorified SUV’s that are also not meant for towing high loads. They’re all around 7,000 lb GVWR, which is no different than a V8 SUV. 60 sq-ft is a lot for a bumper pull. 5th wheels are rated to 75 sq-ft, it’s safer towing.

Having enough “power” to pull it and withstanding the duty cycle of towing long term are also two different things. Ever notice how every 3/4 and 1 ton truck still only use an iron engine block instead of aluminum..?

If it’s ok to exceed J2807’s frontal area limit should be a discussion reserved for the 3/4 and 1 ton trucks that are designed/ built to tow. Light duty vehicles should stick to manufacturer specified limits.
 

·
Registered
Joined
·
149 Posts
I didn't see anyone mention it specifically. I saw the 2000 limit and the 3500 limit tossed out there. They are both correct. The JK (2-door) is limited to 2000. The JKU (4-door) is limited to 3500. It has to do with the body length and weight and the distance between the wheels. As a side-note, the exact same drivetrain used in the dodge Dakota is rated at 5000 pounds.

Everything else is true, the trailer package includes nice things, like heavier rear springs, transmission oil cooler, so more to consider.

Mike-5.
 

·
Super Moderator
Joined
·
2,728 Posts
As a side-note, the exact same drivetrain used in the dodge Dakota is rated at 5000 pounds.

Everything else is true, the trailer package includes nice things, like heavier rear springs, transmission oil cooler, so more to consider.

Mike-5.
The 3.6 was never put in the Dakota.

But yes, a 3.6 WK2/WD had a 5k tow rating with the WA580....but they have an entirely different chassis and suspension setup. Engine & transmission are not the only factors in tow ratings

No, a transmission cooler was not exclusive to the max tow package. It was a standard feature for 2012-18 automatic JK
 

·
Administrator
Joined
·
17,026 Posts
Discussion Starter · #85 ·
I didn't see anyone mention it specifically. I saw the 2000 limit and the 3500 limit tossed out there. They are both correct. The JK (2-door) is limited to 2000. The JKU (4-door) is limited to 3500.

Everything else is true, the trailer package includes nice things, like heavier rear springs, transmission oil cooler, so more to consider.

Mike-5.
Lots of misinformation here. Sorry, not trying to be a jerk, just posting the facts. (y)
Please read the towing thread for all the details LINK
Specifically:
  • Not all two doors have the 2,000 pound towing, some have 3,500, some have 1,000 (depends on year and gearing)
  • Not all 4 doors have 3,500, some are as low as 1,000. (depends on year and gearing)
  • All 2012+ auto JKs have a trans cooler (and sway control), it was never part of any tow package.
  • No tow package included heavier springs.
 

·
Super Moderator
Joined
·
2,728 Posts
I couldn’t find a GCWR for the Jeep, but for a Sport or Sahara, I found the rated curb weight and payload to be equal to 5,291 and a trailer capacity of 3500, which would indicate a GCWR of 8,791. With the curb weight listed between 4,000 and 4,300 lbs and the payload listed between 1,000 and 1,200 lbs (using round numbers) anyone with a rig over 6,000 lbs is already exceeding the GVWR and overloading the axles. The Rubicons are rated slightly higher, likely due to the Dana 44 front axle.


Sent from my iPhone using Tapatalk
You can’t add the numbers together to get GCWR.

GCWR for JKU with 3.21 is about 6,500 lbs and ~8,000 lbs for 3.73/4.10

GVWR for 4-door Sport and Sahara is around 5300-5500 lbs and 5700 lbs for Rubicon
 

Attachments

·
Premium Member
Joined
·
9,626 Posts
.......slippery slope......
I am not sure it is a slippery slope especially when it comes frontal area ratings. IMO Ford is the only one to do it correctly, frontal area is the combine tow vehicle frontal area and any part of the trailer that extend out past the tow vehicles shadow. And even this is problematic because it does not take into account streamlining of the trailer. A flat nose cargo trailer is much harder to pull than a v-nose trailer.

The frontal area of the Jeep is easily 25 sq. ft. and probably close to 32, especially on a lifted rig. Meaning pretty much that Jeeps wants us to pull inside the shadow of our rigs. Anything sticks out past the shadow and you've busted the spec.

And is frontal area really a hard and fast spec as compared to tongue weight or max trailer weight. Not really, it is a performance limitation which can be addressed by power adders, improved cooling etc.
 

·
Super Moderator
Joined
·
2,728 Posts
IMO Ford is the only one to do it correctly, frontal area is the combine tow vehicle frontal area and any part of the trailer that extend out past the tow vehicles shadow.
I can see how the wording is slightly confusing, but Ford’s limit does specifically say “maximum trailer frontal area” not “maximum vehicle/trailer combo frontal area”
 

Attachments

·
Administrator
Joined
·
17,026 Posts
Discussion Starter · #89 ·
Seems pretty cut & dry to me..??
The Jeep owner's manual specifically says the frontal area is the height x width of the front of the trailer.
What Ford says or does is irrelevant in this case IMO

4453000
 

·
Premium Member
Joined
·
9,626 Posts
.........GCWR for JKU with 3.21 is about 6,500 lbs and ~8,000 lbs for 3.73/4.10......
Per the manual for a 2017 JKU GCWR is:

Sport
3.21 gears - 7400 lbs
3.73 gears - 8900 lbs

Sahara
3.21 gears - 7500 lbs
3.73 gears - 9000 lbs

Rubicon
3.73/4.10 gears - 9200 lbs.
 

·
Super Moderator
Joined
·
2,728 Posts
Per the manual for a 2017 JKU GCWR is:

Sport
3.21 gears - 7400 lbs
3.73 gears - 8900 lbs

Sahara
3.21 gears - 7500 lbs
3.73 gears - 9000 lbs

Rubicon
3.73/4.10 gears - 9200 lbs.
Interesting that they have different numbers posted on the product spec vs the manual for 2017-18. Being listed ~770-1000 bs higher than 2012-16 without any changes, have to wonder if it’s a misprint
 

Attachments

·
Premium Member
Joined
·
9,626 Posts
Interesting that they have different numbers posted on the product spec vs the manual for 2017-18. Being listed ~770-1000 bs higher than 2012-16 without any changes, have to wonder if it’s a misprint
The 2016 manual is exactly the same as the 2017 and 2018. It is also those years that the JK has the same towing capacity as the JKU though GCWR is 500 lbs less. Approx the weight difference the JK and JKU. Most of us believe this is due to J-2807.

Also remember that the Wranglers can pull much more weight overseas than in the US. Part of that is bigger brakes but most of it has to do with national speed limits of around 60 mph allowing lower tongue weights.
 

·
Super Moderator
Joined
·
2,728 Posts
The 2016 manual is exactly the same as the 2017 and 2018. It is also those years that the JK has the same towing capacity as the JKU though GCWR is 500 lbs less. Approx the weight difference the JK and JKU. Most of us believe this is due to J-2807.

Also remember that the Wranglers can pull much more weight overseas than in the US. Part of that is bigger brakes but most of it has to do with national speed limits of around 60 mph allowing lower tongue weights.
J2807 wouldn’t make sense though, as the GCWR ratings went back down to ~8,000 lbs for JL
 

Attachments

·
Premium Member
Joined
·
9,626 Posts
Seems pretty cut & dry to me..??
The Jeep owner's manual specifically says the frontal area is the height x width of the front of the trailer.
What Ford says or does is irrelevant in this case IMO

View attachment 4453000
IMO it is not that simple. Which would be easier to tow, a trailer that is 4 ft tall and 8 feet wide or one that is approx 5.6 x 5.6. Both are 32 sq ft but the 5.6 x 5.6 is in the slip steam of the vehicle.


I can see how the wording is slightly confusing, but Ford’s limit does specifically say “maximum trailer frontal area” not “maximum vehicle/trailer combo frontal area”
It is not confusing at all.

Frontal Area is the total area in square feet that a moving vehicle and trailer exposes to air resistance. The chart above shows the maximum trailer frontal area that must be considered for a vehicle/trailer combination. Exceeding these limitations may significantly reduce the performance of your towing vehicle.
The figures that Ford gives is total frontal area of the combine vehicle/trailer trailer. This is not obvious when looking at the F150. But look at the Ranger. Without the trail towing package the Ranger is limited to the frontal area of the vehicle, 30 sq ft, the trailer frontal area must be in the slip stream. Add the tow package and the frontal area jumps to 55 sq ft, you have an additional 25 square feet to work with outside the vehicle slip stream.

IMO the reason it is ignored so much is the manufactures have not given us the tools to properly evaluate it's importance. Ford has at least provided some level of explanation and we know that exceeding the spec will impact performance. Can I mitigate the performance issue? Does it impact safety, if so how? How do I calculate the difference between a flat nose trailer and one that has been streamlined, wind resistance is going to be vastly different?
 

·
Premium Member
Joined
·
9,626 Posts
J2807 wouldn’t make sense though, as the GCWR ratings went back down to ~8,000 lbs for JL
J2807 is the only thing that makes sense when looking at the difference between 2012-2015 and 2016-2018. I have looked thru all the parts between the years and there is no difference. And as far as I know there is no difference in software either.

As far as the JL goes just look at the frontal area differences, 25 vs 20 for the 2 door and 32 vs 30 for the 4 door. Even though I was hoping that the JL was going to be better at towing it looks like it is a little worse other than the diesel. Also looking at the axle the JL front axle looks more capable, 2850 vs 2775, but the rear the JK is stronger, 3200 vs 3000.
 

·
Registered
Joined
·
10,420 Posts
Are we getting into aerodynamics and dancing around drag? That involves the drag coefficient, frontal area, air density, and velocity.

"Streamlining" might change the drag coefficient, but frontal area is still frontal area.
 

·
Administrator
Joined
·
17,026 Posts
Discussion Starter · #97 ·
Hey guys, we have a couple of tow threads going on right now that are very similar, I'm going to merge them both into the main JK Tow Thread for easier reference in the future.
 

·
Premium Member
Joined
·
9,626 Posts
Are we getting into aerodynamics and dancing around drag? That involves the drag coefficient, frontal area, air density, and velocity.

"Streamlining" might change the drag coefficient, but frontal area is still frontal area.
When the manufacture is talking frontal area in towing and reduced performance if exceeding the frontal area it is all about drag.
 

·
Super Moderator
Joined
·
2,728 Posts
It is not confusing at all.

The figures that Ford gives is total frontal area of the combine vehicle/trailer trailer. This is not obvious when looking at the F150. But look at the Ranger. Without the trail towing package the Ranger is limited to the frontal area of the vehicle, 30 sq ft, the trailer frontal area must be in the slip stream. Add the tow package and the frontal area jumps to 55 sq ft, you have an additional 25 square feet to work with outside the vehicle slip stream.

IMO the reason it is ignored so much is the manufactures have not given us the tools to properly evaluate it's importance. Ford has at least provided some level of explanation and we know that exceeding the spec will impact performance. Can I mitigate the performance issue? Does it impact safety, if so how? How do I calculate the difference between a flat nose trailer and one that has been streamlined, wind resistance is going to be vastly different?
Ford literally says “The chart above shows the maximum trailer frontal area”

It does not include the vehicle.

The increase in allowable frontal area with the tow packages is due to the additional cooling /gearing it provides
 

Attachments

·
Registered
Joined
·
307 Posts
Please read the towing thread for all the details LINK
Specifically:
  • Not all two doors have the 2,000 pound towing, some have 3,500, some have 1,000 (depends on year and gearing)
  • Not all 4 doors have 3,500, some are as low as 1,000. (depends on year and gearing)
  • All 2012+ auto JKs have a trans cooler (and sway control), it was never part of any tow package.
  • No tow package included heavier springs.
Yes and the Max Tow only particularity is probably that the Rear Differential came with 75W-140 (instead of 80W-90). I do not remember anybody refering to this. Hint: the 2018 Owner's Manual states "For trailer towing, use... 75W-140) (reference, 2018 Owner's Manual, page 435)
:)
 
81 - 100 of 143 Posts
Top