Meety Peety

Hey guys, I'm new here and a little confused about the tow rating and gearing on my Jeep. I have a 2012 Unlimited Sport (3.6L Auto) which I always thought was geared 3.73 stock. I am getting ready to regear it and was planning on going to 4.88 (Already on 35's) and figured I might as well request a build sheet just to be sure I don't need to buy a new carrier. Well, Got the build sheet this morning and it says I have 3.21 gears and a tow package with trailer sway damping (But evidently not the "Max tow" package). Here's where I get confused.

I always thought ALL 2012 Unlimited Autos come with 3.73 gears stock? I have seen this posted a few times and in my manual (2012 edition) it doesn't even show an option listed for a 3.6L Auto with 3.21s. Reading a little bit online, I have seen a few people talking about early models (Mine is 3/7/12) coming with 3.21s stock unless you buy the "max tow" package and that even with the standard tow package you can end up with 3.21s. I bought this Jeep used in 2014 and wasn't aware of this at the time, just figured tow package was good to go. At the time, I had no plans to tow with this vehicle. I am OK with buying a carrier when I do the regear, but I am now wondering what else may affect my tow rating (Or my ability to tow) even after the regear? Since I don't even see a 3.21 Unlimited Auto listed in my manual for towing capacity, is it fair to assume that my rating will be 3500# if I regear to 4.88/35 (Closer to the equivalent of 3.73/stock tire)? The only 3.21 Unlimited I see is a Manual trans rated at 1000# - a major drop from the 3500# I was expecting from "All Unlimited models" shown on the Jeep website. Is this solely due to the gearing of the Jeep or is there more to it than that? I'm also a bit confused as to why they would sell a Jeep with 3.21s and a tow package but not acknowledge it in the manual, especially in terms of towing capacity (the liability that comes along with exceeding this).

I am going to go home today and throw it on jacks to see if I can figure out my current gearing the hard way, but I'm not sure where to go from here. Assuming that I had 3.73s, I went on a "test run" with a 1700# (empty) flatbed trailer last weekend and did less than stellar and power was definitely lacking. No issues with stopping or sway, just a serious lack of power. The transmission was hunting pretty bad and going up some steeper grades the RPMs were out of my comfort zone. I was hoping that a regear would fix it, but now I'm questioning my GVWR and GCWR capabilities too? My GVWR is listed on the door sticker, but GCWR is only shown in the manual, and there is no value for my apparent configuration. For what it's worth, I'm only looking to pull about 2000# combined trailer weight but will be going up a couple of mild grades. Being so heavy (Bumpers, sliders, winch etc) and with the gear ratio that I currently have (I was wondering why 3.73s were THAT bad?) I already struggle a bit on steep grades without a trailer and would rather not over stress the vehicle if it just can't handle it.

Thanks in advance for any advice you can give me.

Invest2m4

3.21 is always standard on non-Rubicon. Rubicon autos are 3.73 with the option for 4.10. It is very rare to see a non-Rubicon with 3.73 gears that was not a custom order by the customer. You have the trailer tow package, which means 3.21 unless the dealer opted for the 3.73 ratio (which again, they don't do because most buyers have no clue what it means and have no desire to pay $495 for it). Plus, most dealers think it hurts MPG and don't want to have to further explain it.

A new carrier isn't a big deal, they are pretty cheap. If you are going in to the work, may as well upgrade the carriers too. Maybe selectable lockers or an LSD rear.

You'll want to try to get the tongue weight right and it will tow a lot better for you. The real issue are the crap JK brakes. If you plan to tow a lot, use a trailer with brakes or upgrade the front brakes or front and rear.

By tomorrow, someone will chime in and tell you about how they towed 7k lbs with their 2 door JK through CO. Be smart and be safe.

iron53man

Just as the other guy stated... Unless it's classified as max tow package (rather than just a tow package) it will be 3.21, south of the Rubicon. I got a 2015 JKU Sahara with a tow package and it's 3.21 gearing. As far as towing capacity... Pretty much every JKU (to an extent) should be able to tow a max of 3,500 pounds per the manufacturer specs. Gearing shouldn't affect the physical two weight too much. The gearing will affect how smooth, mpg while towing (and w/o), the physical power and get-up-and-go you have while driving, along with brakes. jeep brakes suck by themselves, before you even add towing to the equation.

Then again, i'm far from an expert so by no means take my word for it. Someone may come on here and tell me i'm an idiot... ya never know.

Ajkaz

I regularly tow a 1400lb loaded camper with my 2 Door, 3.8 6sp on 37s w/ 4.88's; like stated before trailer brakes are an absolute must. I can comfortably get to 65 mph and that's where I cruise and normally 55-60 up long hills in 4th around 3200K rpm. When towing anything in CA the speed limit is 55 mph. Though I am happy with the way the jeep performs and handles towing, with the weight of armor, 37's and the trailer I don't intend on ever towing anything heaver.

rob_engineer

Haha. I'm that guy that's gonna say how much I tow. I have 2012 JKU manual trans with 3.73 rear. Stock suspension and tires. I've put over 5000 miles towing a trailer that weighed 4000 - 5000 pounds depending whether I had the motorcycles loaded in the toyhauler. It handled it. I only towed in NJ, PA, and VA. I wouldn't recommend in serious mountains. I used a weight dist hitch. Trailer had dual axle trailer brakes. I always felt in control. Top speed about 65 mph. Gas mileage drops to about 10 - 11. The Jeep rating of 3500 is artificially low. The exact same gas powered Jeep is rated for 4400 pounds on the Jeep website in other countries such as Australia.

The smittybilt XRC rear bumper is a tremendous upgrade if you tow heavy loads. It really makes the weight distribution hitch work much more effectively. It's rated for 5000 pounds.

nthinuf

If I read it right: you are concerned that because you have stock 3.21's (instead of 3.73's), you are thinking that even after you regear to 4.88, the simple fact that you started with 3.21's in some way makes your jeep less tow-worthy than if it had started life with 3.73's? Correct?

Other than the gears, I don't think there are any differences. Same engine, same transmission, same axle housings, same cooling system, etc, etc. Once you upgrade the gears, your jeep will be just as capable as any other 4door jk with that engine/trans/gear ratio.

I have an 08 with the weak 3.8, and other than the lack of power, have had no issues towing either a ski boat or fully loaded 6x12 enclosed uhaul trailers, all of which are up near the 3500 lb limit. I have towed 15 hour trips up and down between colorado and texas with 3.73, 5.13, and now 5.38, and with 32's, 33's, 35's, and now 37's. Gutless, but no issues...

Meety Peety

Thanks for the input guys. So it seems that if I go ahead and regear to 4.88 I should be ok? I will look into trailer brakes and what all is involved with installing a controller.. but for the mean time I will look into HD rotors and pads. Oddly enough, when I did my test run with the 1700# trailer braking was no problem, and my pads are probably nearing the end of their life here pretty soon.

Invest2m4

You are sort of correct. Brakes are the first reason the rating in the U.S. is lower. All other countries have larger brakes. There are a couple other differences that I am forgetting, but that is the big one. The issue for most novice people is they add a crap ton of weight to the Jeep, pack the family in and want to toss a 3k lb trailer on that doesn't have trailer brakes. May as well cut a hole in the floor boards and use your feet to stop.

Larger brakes are now a fairly low cost upgrade for anyone doing a lot of towing. You really can't beat the Dynatrac package. Shoot, even for people who don't tow, it is a good upgrade.

Monte417

Come on man 1k for pads calipers and brackets? I'd pay half that maybe

Invest2m4

Edit: I thought they came with new calipers. They reuse the stock. I take back my earlier comment. Get some J8 stuff.