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Old 06-11-2019, 02:26 PM   #31
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Somebody posted it before, but just for a reference and to eliminate confusion, here are a few pages from 2017 owner's manual. Starting from 2016, JK and JKU are rated the same (no difference in tow limits due to wheelbase).

BTW, I looked at 2012 OM, and the numbers are very different: 3.21 gears are limited to 1000 lbs for both JK and JKU, the rest of JK were limited to 2000 lbs, and the rest of JKU were limited to 3500 lbs.

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Old 06-11-2019, 02:30 PM   #32
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I'll tell you one capability that is improved, pulling that boat up a steep ramp without having to go 4wdlo

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Old 06-11-2019, 02:47 PM   #33
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We're confusing correlation with causality. Just look at the first two listings- 2 door Sports with manuals. Does the ring & pinion set change the CGWR, or do different packages that result in different GCWRs come with different gear ratios?

It's not the feathers that make a chicken.
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Old 06-11-2019, 02:57 PM   #34
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Originally Posted by Lost in the woods View Post
We're confusing correlation with causality. Just look at the first two listings- 2 door Sports with manuals. Does the ring & pinion set change the CGWR, or do different packages that result in different GCWRs come with different gear ratios?

It's not the feathers that make a chicken.
No idea. It could be that test methodology changed somewhere around 2016.
My guess is that 3.21 gears and lower tow limit are likely related to drivability, engine/transmission load and heat. It's not just acceleration from stop but also pulling uphill.

They could also introduce some software changes that made JK and JKU have the same limits, like some independent brake actuation to counteract sway (some part of ESC).
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Old 06-12-2019, 01:42 AM   #35
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Originally Posted by Lost in the woods View Post
We're confusing correlation with causality. Just look at the first two listings- 2 door Sports with manuals. Does the ring & pinion set change the CGWR, or do different packages that result in different GCWRs come with different gear ratios?

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Originally Posted by invariant View Post
No idea. It could be that test methodology changed somewhere around 2016.
My guess is that 3.21 gears and lower tow limit are likely related to drivability, engine/transmission load and heat. It's not just acceleration from stop but also pulling uphill.

They could also introduce some software changes that made JK and JKU have the same limits, like some independent brake actuation to counteract sway (some part of ESC).
This is not rocket science, it is just the gearing. Axles don't change unless you get the Rubicon. Spring packages do change but that is to more or less to ensure that all Wranglers have about the same payload.
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Old 06-12-2019, 05:27 AM   #36
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Gearing changes do not change your liability if you are deemed at fault in an accident where you exceeded the stated factory vehicle towing limits.
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Old 06-12-2019, 08:50 AM   #37
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Wrangler tow capacities (or lack thereof) have long been a point of discussion. I am not sure why Jeep rates them the way they do, soft suspension, wheelbase, soft top, brakes, cooling, owners mod them, the list goes on. I am quite sure they are erring on the side of caution given a variety of factors. The powertrain is obviously capable of more; example 2011 grand cherokee with the same 3.6 engine and 5 speed automatic is rated for 5000 with a 3.07 axle ratio. Coolant capacity on the GC is almost identical to the JK/JKU. I also don't completely buy in to the short wheelbase argument especially with the 2dr. Look at the some of the short wheelbases on the cabover trucks of the 70's and 80's, especially the single rear axles. I drove one for a while in the late 70's with a refer semi trailer delivering milk. I believe the wheelbase on that truck was shorter than a JKU, something like 110" and weighed about 35000 loaded. That rig sure was easy to maneuver in tight areas and no stability issues at highway speeds. Personally I tow an 18 foot bass boat with my 2dr JK with no problems. Not sure what the total weight is but the hull is about 1000, 400 for the engine, 3 batteries, trolling motor and gear, certainly over the 2000 lb limit. One advantage a Wrangler has is a very short rear overhang putting the hitch weight close to the rear axle giving the trailer less of a lever to push the rear of the vehicle. Not like a fifth wheel or semi trailer but better than a typical P/U or SUV. FWIW my JK is basically stock height, LT265/70R17C tires, Rancho 7000 shocks. I don't tow over 65mph. I subjected my rig to the portions of J2807 I could duplicate locally and it easily exceeded the minimum standards by a considerable margin.
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Old 06-12-2019, 11:36 AM   #38
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Wrangler tow capacities (or lack thereof) have long been a point of discussion. I am not sure why Jeep rates them the way they do, soft suspension, wheelbase, soft top, brakes, cooling, owners mod them, the list goes on. I am quite sure they are erring on the side of caution given a variety of factors. The powertrain is obviously capable of more; example 2011 grand cherokee with the same 3.6 engine and 5 speed automatic is rated for 5000 with a 3.07 axle ratio. Coolant capacity on the GC is almost identical to the JK/JKU. I also don't completely buy in to the short wheelbase argument especially with the 2dr. Look at the some of the short wheelbases on the cabover trucks of the 70's and 80's, especially the single rear axles. I drove one for a while in the late 70's with a refer semi trailer delivering milk. I believe the wheelbase on that truck was shorter than a JKU, something like 110" and weighed about 35000 loaded. That rig sure was easy to maneuver in tight areas and no stability issues at highway speeds. Personally I tow an 18 foot bass boat with my 2dr JK with no problems. Not sure what the total weight is but the hull is about 1000, 400 for the engine, 3 batteries, trolling motor and gear, certainly over the 2000 lb limit. One advantage a Wrangler has is a very short rear overhang putting the hitch weight close to the rear axle giving the trailer less of a lever to push the rear of the vehicle. Not like a fifth wheel or semi trailer but better than a typical P/U or SUV. FWIW my JK is basically stock height, LT265/70R17C tires, Rancho 7000 shocks. I don't tow over 65mph. I subjected my rig to the portions of J2807 I could duplicate locally and it easily exceeded the minimum standards by a considerable margin.
Wheel base has very little to do with what you can pull safely. When we look at pickup trucks a standard cab pickup can pull more than a crew cab. That is because the standard cab as a higher payload rating than the crew cab.

The only time a longer wheel base helps is if something goes wrong. The longer wheel base vehicle reacts slower giving the drive more time to react and less of a chance of over reacting. In shorter vehicle it happens fast and it is easy to over correct. In both cases the trailer caused the issue, be it do to slick roads or high winds. This is provided the trailer was loaded correctly for speeds being driving.

FYI: If you are using some type of stabilization system in slick condition disconnect it.

IMO there are a couple of reason for the low tow ratings. The first being the speeds we can legally tow, 85 mph in some states. The second reason is our payload very low, only around 1000 lbs. To pull 5000 pound you would need at least 500 lbs of tongue weight because of the speeds we can run. Beside not having a hitch that would work for that weight using 50% of your payload does not leave much room for fuel, passengers and luggage. Last is the marketing guys. If the JK can pull the same as a JKU they are not happy. They make more money on the JKU and people that would rather have a 2 door but pull have to move up into the 4 door.
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Old 06-12-2019, 02:42 PM   #39
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I also don't completely buy in to the short wheelbase argument especially with the 2dr. Look at the some of the short wheelbases on the cabover trucks of the 70's and 80's, especially the single rear axles. I drove one for a while in the late 70's with a refer semi trailer delivering milk. I believe the wheelbase on that truck was shorter than a JKU, something like 110" and weighed about 35000 loaded. That rig sure was easy to maneuver in tight areas and no stability issues at highway speeds.
Those semi trucks put the pivot point directly above the rear axle. Same as you do with a pickup truck 5th wheel or goose neck trailer. Doing that drastically changes the dynamics of the load. Any bumper pull trailer puts the pivot way behind the rear axle and that leverage makes a huge difference. I don't know tow ratings of specific pickups off hand but I do know that the goose neck or 5th wheel rating is a whole lot higher than the bumper pull rating. I want to say it's in the neighborhood of 2x the weight between the two.

If I put a goose neck hitch in the back of my 2dr JK, I'm sure I could safely tow a whole lot more than the 2,000 pounds my Jeep was rated for.
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Old 06-12-2019, 06:43 PM   #40
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Those semi trucks put the pivot point directly above the rear axle. Same as you do with a pickup truck 5th wheel or goose neck trailer. Doing that drastically changes the dynamics of the load. Any bumper pull trailer puts the pivot way behind the rear axle and that leverage makes a huge difference. I don't know tow ratings of specific pickups off hand but I do know that the goose neck or 5th wheel rating is a whole lot higher than the bumper pull rating. I want to say it's in the neighborhood of 2x the weight between the two.

If I put a goose neck hitch in the back of my 2dr JK, I'm sure I could safely tow a whole lot more than the 2,000 pounds my Jeep was rated for.
And using the same principles, a 2.5" lift and larger tires will make the pivot even farther away from the axle and the Jeep a less stable a platform for towing. But the OP thinks a different gear ratio will bypass those problems and increase towing capacity.
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Old 06-12-2019, 07:18 PM   #41
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The JKU Owner's Manual is very clear about the subject of towing; the maximum towing weight is limited by the gearing, and only by the gearing.

For my 2018 JKU, it is 2,000 lbs for 3.21, and 3,500 lbs for 3.73 and 4.10.

Nothing in the manual says that the maximum towing weight is limited to the factory installed gearing.

People who bring legalities in the picture seems to be unaware of what I wrote above.

But, it seems that several Jeeps are being driven on the roads with tires size totally different from the tire size specified for the Jeep, and the specified tires sizes are clearly identified in the Jeep's door jam. Yet these Jeep owners do not seems concerned by the legalities of their "modifications".

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Old 06-12-2019, 07:33 PM   #42
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And using the same principles, a 2.5" lift and larger tires will make the pivot even farther away from the axle and the Jeep a less stable a platform for towing. But the OP thinks a different gear ratio will bypass those problems and increase towing capacity.
Now that really depends on the lift installed. I promise you mine tows much better lifted than it ever did stock. The lift and larger tires don't change the pivot point at all provide you use to correct drop hitch. Larger tires provided you use the correct offset gives you a wider track width making the vehicle more stable. Plus a wider tire increases the coefficient of friction. Stiffer springs, strong control arms, bushing that don't deflect like stock all provide for a better tow vehicle.
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Old 06-12-2019, 09:37 PM   #43
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The JKU Owner's Manual is very clear about the subject of towing; the maximum towing weight is limited by the gearing, and only by the gearing.
Okay, you got me. It is only the gears. I read back through the owner's manual pages that Invariant posted, and figured out that you're right. So if you get 3.73s, make sure you get the ones from the 4 door Rubicon that give you the 9200# GCWR instead of the cheapos from the 2 door Sport that'll only give you the 8400# GCWR. You'll still get the 3500# tow rating, but wouldn't you rather get the Rubicon 3.73s and be able to load 800 pounds more inside the Jeep than if you got the cheapo 3.73s from the Sport?

If the owner's manual isn't just using gear ratios as an easy telltale to help you find your GCWR, if it's really a modification guide, then don't be tricked into buying any old 3.73 set, get the Heavy Duty Rubicon 3.73s. The Owner's Manual is very clear.
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Old 06-12-2019, 10:51 PM   #44
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Okay, you got me. It is only the gears. I read back through the owner's manual pages that Invariant posted, and figured out that you're right. So if you get 3.73s, make sure you get the ones from the 4 door Rubicon that give you the 9200# GCWR instead of the cheapos from the 2 door Sport that'll only give you the 8400# GCWR. You'll still get the 3500# tow rating, but wouldn't you rather get the Rubicon 3.73s and be able to load 800 pounds more inside the Jeep than if you got the cheapo 3.73s from the Sport?

If the owner's manual isn't just using gear ratios as an easy telltale to help you find your GCWR, if it's really a modification guide, then don't be tricked into buying any old 3.73 set, get the Heavy Duty Rubicon 3.73s. The Owner's Manual is very clear.
The 4 door gears add about 800 pounds to the JK.
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Old 06-13-2019, 02:13 AM   #45
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The 4 door gears add about 800 pounds to the JK.
And the 4 door gets the largest springs.
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Old 06-13-2019, 05:33 PM   #46
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Sorry, wrong, selective reading and seemingly deliberate misunderstanding at levels usually only attainable by 13 year olds have determined that the springs have nothing to do with the amount of weight a vehicle can handle. It's all about the gearing. The owner's manual says so.
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Old 06-13-2019, 06:06 PM   #47
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...It's all about the gearing. The owner's manual says so.
You are being sarcastic, but do you have any other document that contradict the Owner's Manual?

Except for the User's Manual and the Owner's Manual, as far as I know FCA is not providing any other documentation.

Everything else is pure speculation, based on belief; not on facts.

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Old 06-13-2019, 07:11 PM   #48
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You are being sarcastic, but do you have any other document that contradict the Owner's Manual?

Except for the User's Manual and the Owner's Manual, as far as I know FCA is not providing any other documentation.

Everything else is pure speculation, based on belief; not on facts.

I am fairly sure he does not have a point. Regardless of the GCWR the GTW is either 2000 lbs based on 3.21 gears and 3500 lbs based on 3.73 or 4.10 gears.
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Old 06-13-2019, 10:10 PM   #49
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I'm not contradicting the owner's manual, I'm calling out the idea of faith-based tow ratings as being full of $#*+.

It is silly to assume that without changing the overall amount of weight the frame is rated to handle, a simple gearing change from 3.21 to 3.73 will give you a 75% increase by in the amount of weight the frame can safely tow. By that math, taking a Rubicon and swapping in 3.21s would suddenly make it lose its rating to handle a 3500# trailer while not reducing its GCWR by even one pound when all you've done is change the final drive ratio. You could "fix" that by a simple downshift. Hey- maybe towing in a lower gear is all that it takes to increase your tow rating! That might be why some "tow" settings on automatic transmissions lock out overdrive, to increase the amount of weight they can safely tow.

Really- a factory brochure about features and ratings isn't a modification guide. If a color chart in the owners manual showed that blue was only available on Rubicons, would painting your Sport blue make it a Rubicon? If you're just going to cut and paste numbers randomly around the owner's manual to make things look like they match, why not just move the tow rating numbers to match the Jeep you've got and call it good? You probably won't get in an accident anyway, even if you do the police and your insurance company probably won't notice, and if they do then your juggled owner's manual isn't going to save you. So why go through the hassle?
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Old 06-13-2019, 10:44 PM   #50
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I'm not contradicting the owner's manual, I'm calling out the idea of faith-based tow ratings as being full of $#*+.

It is silly to assume that without changing the overall amount of weight the frame is rated to handle, a simple gearing change from 3.21 to 3.73 will give you a 75% increase by in the amount of weight the frame can safely tow. By that math, taking a Rubicon and swapping in 3.21s would suddenly make it lose its rating to handle a 3500# trailer while not reducing its GCWR by even one pound when all you've done is change the final drive ratio. You could "fix" that by a simple downshift. Hey- maybe towing in a lower gear is all that it takes to increase your tow rating! That might be why some "tow" settings on automatic transmissions lock out overdrive, to increase the amount of weight they can safely tow.

Really- a factory brochure about features and ratings isn't a modification guide. If a color chart in the owners manual showed that blue was only available on Rubicons, would painting your Sport blue make it a Rubicon? If you're just going to cut and paste numbers randomly around the owner's manual to make things look like they match, why not just move the tow rating numbers to match the Jeep you've got and call it good? You probably won't get in an accident anyway, even if you do the police and your insurance company probably won't notice, and if they do then your juggled owner's manual isn't going to save you. So why go through the hassle?
Frames are the same Sport or Rubicon. A dual top Sport can very well have larger springs than a soft top Rubicon. The only unique spring package was the 10A and the Recon. And while your last comments here might have some merit we have been modifying vehicles ability to tow or carry larger payloads for years.

Anyway go out and do your home work. But I would not bother, we already have. Frames are the same, springs a based on the overall package of the vehicle, brakes are the same, transmissions are the same, rearends are the same, Front ends for the Rubicon are larger but it does not allow it to pull a larger trailer.

It is a gearing issue plan and simple. I could show you the math but I need to get to bed as I am on my way to Alaska for a couple of weeks.
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Old 06-13-2019, 11:05 PM   #51
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So, when ordering a JKU, apparently getting 3.73 gears must get you different springs, a heavier frame, a different suspension, heavier duty axle, or something.

Jeep must camouflage things well because the parts books don't show different part numbers for any of that. But apparently a gear ratio change alone can not possibly be responsible for a change in GTWR on a vehicle. I'm glad I can come here and learn these things from the experts.
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Old 06-13-2019, 11:20 PM   #52
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Re-Geared. Change Towing Capabilities?

Lol so if it’s just the gears then why is the towing max 3500lbs the same with 3.73 and 4.10 yet less with the 3.21. This sounds more like a “cover your ass” statement. One would think if this is their method of setting Tow max then the 4.10 should be able to Tow an extra 1000lbs over the 3.73.


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Old 06-13-2019, 11:35 PM   #53
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Lol so if it’s just the gears then why is the towing max 3500lbs the same with 3.73 and 4.10 yet less with the 3.21. This sounds more like a “cover your ass” statement. One would think if this is their method of setting Tow max then the 4.10 should be able to Tow an extra 1000lbs over the 3.73.


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The suspension is the limiting factor. As well as engine cooling.

That is, unless you have 3.21 gears. Then the acceleration is the limiting factor.
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Old 06-13-2019, 11:50 PM   #54
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The suspension is the limiting factor. As well as engine cooling.

That is, unless you have 3.21 gears. Then the acceleration is the limiting factor.


Suspension wise there is little difference. 1 notch up the spring ladder maybe for the Max Tow package. I’ve worked on Jeeps that had the same spring numbers with and without Tow package. Shocks are the same Max Tow or not, 3.21 or 3.73 gears.
Apparently in Europe the towing capacity is higher.


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Old 06-14-2019, 12:06 AM   #55
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Suspension wise there is little difference. 1 notch up the spring ladder maybe for the Max Tow package. I’ve worked on Jeeps that had the same spring numbers with and without Tow package. Shocks are the same Max Tow or not, 3.21 or 3.73 gears.
Apparently in Europe the towing capacity is higher.


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Europe has a max speed limit when towing regardless of the highway you're on. Something like 60 MPH in England. Mabe 100KPH in other parts of Europe. You can tow more weight safely (and without overheating) when you limit your speed.
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Old 06-14-2019, 02:57 AM   #56
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Lol so if it’s just the gears then why is the towing max 3500lbs the same with 3.73 and 4.10 yet less with the 3.21. This sounds more like a “cover your ass” statement. One would think if this is their method of setting Tow max then the 4.10 should be able to Tow an extra 1000lbs over the 3.73.


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Quote:
Originally Posted by JTPhoto JK View Post
Suspension wise there is little difference. 1 notch up the spring ladder maybe for the Max Tow package. I’ve worked on Jeeps that had the same spring numbers with and without Tow package. Shocks are the same Max Tow or not, 3.21 or 3.73 gears.
Apparently in Europe the towing capacity is higher.


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It is a CYA thing for sure, that is a giving. I know in Aussie land there max tow is 4800 lbs or so. But they also have a max tow speed of 100 km. Less speed means less tongue weight required. With the limited payload, around 1000 lbs it really limits what you can safely pull. To pull 3500 lbs at 80 mph you need 350 lbs minimum for tongue weight. To pull at 60 mph you only need 140 lbs. This is the primary reason other countries have higher tow ratings.

I also agree that spring have little to do with max tow capability from what I have seen over the years. Hell I have seen 2 door sports (hard top) with larger springs than I have on my Rubi (soft top). I think Jeep choose it springs for every build to be as close to 1000 lbs payload as possible.

As far as 4.10's being able to pull more, yep it should but I think the limiting factor here is the brakes and besides the CYA aspect that is why it is limited to 3500 lbs. And 4.10's will tow that 3500 lbs easier anyway.
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Old 06-14-2019, 06:37 AM   #57
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The 4 door gears add about 800 pounds to the JK.

The 4 door weighs more than the 2 door


This towing thread reminds me of oil threads. So to throw something else into the mix, this has already been mentioned.



Say you got a JKU, 3.21s, and factory 16" rims
compare to a JKU, 3.73s, and 35s


Towing allowance higher on the one with 3.73s, but in no way is it more capable than the 3.21s with stock wheels/tires
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Old 06-14-2019, 07:38 AM   #58
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The towing on my 08 2 door Rubicon was 2000 pounds. There were no other options except 4 door was higher. Was purely jk vs jku specific rates, no mention of gearing.

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Old 06-14-2019, 07:51 AM   #59
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Easiest answer:
Ride your scooter to Sturgis. Trailers are for boats...
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Old 06-14-2019, 08:58 AM   #60
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I think the people in this thread have put more thought into the max tow rating of the JK / JKU than the FCA engineers have.

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