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Topic Review (Newest First)
11-11-2013 02:51 PM
jk_all_day 4.10s auto setup on my 2014 cant wait to drive.
09-15-2013 06:52 PM
Dwardmba Not sure what happened there. Meant to quote the second part, not the first. Sorry about that.

Pretty sure the down shift will help the lower speed.

I did the math when I bought (the 3.73). I think the 4.1 yields a crawl ratio of ~58 and the 3.73 a 53 or thereabouts. Manual gets you the 73 in the brochure. If it is going to make a difference because of how you use it I'd suggest getting the manual.

Dave
09-15-2013 06:44 PM
Dwardmba
Quote:
Originally Posted by JK Coaster View Post

Interesting that the difference in ratios impact the numbers only 5-7% at 70mph but over 40% at crawl speeds. I know that I am comparing fixed RPM vs. speed in one post, and fixed speed vs RPM in the other, but they show how wide the rear gears are effected by the lower gears in the transmission (and the lower gears in the transfers case when in 4WD low vs. 2WD high).

So here is the crux of the matter. Some would say who cares about the high speed churn at freeway speed, the difference is really very low as a percentage? Others would say, who cares about super low crawl speed and relatively high RPM at such slow speeds? It all depends on how much highway and how much rock crawling we do. Our preferences are really based about how important these opposing requirements play out for us as individuals.

Another important point - Automatic vs. manual transmissions. With 285 HP and a big torque converter, I personally believe more drivers with AT's seem to say they are happy with 3.73's than drivers with manual transmissions. Not saying I have numbers to back this or that 3.73 are any better, it just seems drivers with automatics are maybe less inclined to go lower.

In my mind, the most important consideration is daily drive acceleration and general drivability. I have an auto, 3.73's, 2.72 transfer case and 35's. Some Forum members might say this is over geared but with 285 HP I have never felt so on or off the road. But I have asked myself, would I be happier with a 4.10 to rip a little more around town? Maybe....and I did not take my own advice in the post above and drive both versions before I spent over $30,000. Next time I will and am glad you did.

By the way, what was your impression on the daily drive acceleration and the general drivability of the two Rubicons you tested? I suspect you saw a difference and have a preference..... but would still be pretty happy with either.
Originally Posted by macaw1us
Went to two Dealers today and drove two Rubicons.
Both were 5 speed autos, the one with the 3.73 in 4Lo was going 6 mph at 2000rpm,
the 4,10 was 3 1/2 mph at 2000rpm

Down shift - the auto in low I believe defaults to 2nd gear.

Dave
09-06-2013 12:39 AM
Jstraw
Quote:
Originally Posted by chris4x4 View Post
I got the 4.10's and the auto, and couldn't be happier. Im getting around 17 mpg mixed driving, and the 4.10's make driving in town feel pretty "peppy", whle on the freeway, toeing the throttle to pass, no downshift is needed by the tranny. With the engine as smooth as it is, 80 mph and whatever RPM is nice and smooth, with no hints of engine speed being too high or "buzzy".
My experience to the "T", I enjoy the torque especially on hills, it doesn't jump out of gear and can pull a steep incline pretty well in 3rd gear (auto). I live on top of a hill, so it's my worst mpg drop. I play the Econ game with my dash light most of the time. My tranny functions better when I put a less aggressive tire on. I wonder how the dura tracks compare to a sahara tire?
09-05-2013 10:28 PM
macaw1us I was completely happy with the take off of both the 3.73 and the 4.10 from a stop.
And for me it is very relevant, i'm not concerned about 250 rpm at 70 mph but I was concerned about having as much torque as possible at slow speed to crawl over a rock or creep up a muddy slope.
For me 6 mph at 2000 rpm off road is way to fast, the whole advantage to a Rubicon is it's off road capabilities.
Would I love to get 20+ mpg? Yes, do I want to be able to take it slow and safe over rough stuff and I'm willing to give up some milage? YES
This is why I'm getting a Rubicon, it's not my 1st Rodeo
Low speed gear ratio in a good working rpm and land speed are the only reason I even care about the 3.73 vrs 4.10 debate.
If I were going to be driving this on road all the time, if I were not going to pull a 2000 lb trailer to and from the play grounds and if I wanted to get 20+ mpg, I would get the 3.73 in a heart beat.
I am ordering a 2014 Rubicon X next week because as soon as my house sells I'll be located somewhere on the mountain.
09-05-2013 05:50 PM
chris4x4 I got the 4.10's and the auto, and couldn't be happier. Im getting around 17 mpg mixed driving, and the 4.10's make driving in town feel pretty "peppy", whle on the freeway, toeing the throttle to pass, no downshift is needed by the tranny. With the engine as smooth as it is, 80 mph and whatever RPM is nice and smooth, with no hints of engine speed being too high or "buzzy".
09-05-2013 05:25 PM
JK Coaster
Quote:
Originally Posted by macaw1us View Post
Went to two Dealers today and drove two Rubicons.
Both were 5 speed autos, the one with the 3.73 in 4Lo was going 6 mph at 2000rpm,
the 4,10 was 3 1/2 mph at 2000rpm
Interesting that the difference in ratios impact the numbers only 5-7% at 70mph but over 40% at crawl speeds. I know that I am comparing fixed RPM vs. speed in one post, and fixed speed vs RPM in the other, but they show how wide the rear gears are effected by the lower gears in the transmission (and the lower gears in the transfers case when in 4WD low vs. 2WD high).

So here is the crux of the matter. Some would say who cares about the high speed churn at freeway speed, the difference is really very low as a percentage? Others would say, who cares about super low crawl speed and relatively high RPM at such slow speeds? It all depends on how much highway and how much rock crawling we do. Our preferences are really based about how important these opposing requirements play out for us as individuals.

Another important point - Automatic vs. manual transmissions. With 285 HP and a big torque converter, I personally believe more drivers with AT's seem to say they are happy with 3.73's than drivers with manual transmissions. Not saying I have numbers to back this or that 3.73 are any better, it just seems drivers with automatics are maybe less inclined to go lower.

In my mind, the most important consideration is daily drive acceleration and general drivability. I have an auto, 3.73's, 2.72 transfer case and 35's. Some Forum members might say this is over geared but with 285 HP I have never felt so on or off the road. But I have asked myself, would I be happier with a 4.10 to rip a little more around town? Maybe....and I did not take my own advice in the post above and drive both versions before I spent over $30,000. Next time I will and am glad you did.

By the way, what was your impression on the daily drive acceleration and the general drivability of the two Rubicons you tested? I suspect you saw a difference and have a preference..... but would still be pretty happy with either.
09-05-2013 05:04 PM
Jstraw
Quote:
Originally Posted by badtux View Post
Not irrelevant. The rear end directly affects your crawl ratio, and he was pointing out the difference in crawl (albeit in 2-lo rather than 4-hi) between the two rear ends. One reason why I went with the 4.10... I had 3.73 in my last Jeep and always felt that it was an awkward rear end ratio for a Jeep, you were always going too fast or too slow for any given situation (I had the 6 speed manual).
The transfer case is irreverent to the conversation title and question... the reference is to gas mileage! And as I've stated in this thread, I have a rubicon, I was getting crappy gas mileage on rubicon tires, when I switched to sahara tires, my mileage went to 20ish highway, 17 town! Before that I was getting 15 town and 17 hwy... All because of the friction of the tire! Jeep can't claim a mpg unless its true. It needs to be proven. Brand new rubi tires, went straight on a trip with less then 50 miles on them, I got 20ish, after 500 miles, mileage dropped.

I live in NE PA, hilly as hell here, start stop everywhere I go. I questioned my dealer about my gas mileage before I got my sahara tires, he chalked it up to winter gas and 4:10's... I was pissed I was losing almost 60-70 miles per tank. A deal breaker... More investigation got me to buy a set of road tires as I was told by Chrysler that they have to guarantee the mpg by EPA standards...
09-05-2013 01:36 PM
panthermark
Quote:
Originally Posted by Jstraw View Post
I have 4.10 and was getting lousy gas mileage... Then I bought a set of sahara rims and tires, less then 500 miles of wear, my mileage increased to 20 hwy. it isn't the gears, it's the tires.
I'd say it is both...
*But is also depends on where you live.
*How fast you drive.
*How you use the vehicle.
*And if you have the auto or manual (and I'm assuming we are talking +2012's).

Below 60mph or so...it isn't going to make much of a difference in fuel economy. At 60, on the auto's, on 32" wheels, the difference between 3.73's and 4.10's is about 200 rpms (1950 vs 2144), but both engines would be running in "the solid green". And assuming you are not in a lot of wind or hills....or towing...both are making enough power at their given rpms to keep you from lugging or downshifting.

Once you get above that is where you start to see the difference.

At 70mph, on the auto's, the 3.73's run 2275 rpms...which is in the "dotted green", while the 4.10's run at 2501...which is basically out of the "dotted green"

+2012 manuals run about 100 rpm's lower than the auto's in top gear.

Anything above 75mph does not matter...because the "flying brick" is going to guzzle gas no matter what. At 75mph, on the auto, the 3.73's will run 2438 rpms while the 4.10's will run a buzz happy 2680 rpms.

So really it is between 60mph and 75mph where could see a difference, and that is where most people cruise on the highway.

(As an aside, the 3.21's on the auto will turn 1958 rpms at 70mph. If you are on flat ground without a lot of wind, you should get pretty good fuel economy. And even if downshifts...4th gear at 70mph on the 3.21's will turn 2359 rpms.....that is close to what the 4.10's turn in 5th gear at 2323 rpms).



And yes, tires do make a difference.

I'd say the best factory wheels for the highway/fuel economy are probably the Goodyear SRA's that come on the Sport S. Low rolling resistance and the tires are very light. I won't consider the Goodyear ST's that come on the base Sport because those things are simply awful tires.
09-05-2013 12:11 PM
badtux
Quote:
Originally Posted by Jstraw View Post
Irrevent to the conversation. We all know the 4:1 roktrak is geared for climbing... We are talking about 4.10 rear end
Not irrelevant. The rear end directly affects your crawl ratio, and he was pointing out the difference in crawl (albeit in 2-lo rather than 4-hi) between the two rear ends. One reason why I went with the 4.10... I had 3.73 in my last Jeep and always felt that it was an awkward rear end ratio for a Jeep, you were always going too fast or too slow for any given situation (I had the 6 speed manual).
09-05-2013 11:44 AM
Jstraw
Quote:
Originally Posted by macaw1us View Post
Went to two Dealers today and drove two Rubicons.
Both were 5 speed autos, the one with the 3.73 in 4Lo was going 6 mph at 2000rpm,
the 4,10 was 3 1/2 mph at 2000rpm
Irrevent to the conversation. We all know the 4:1 roktrak is geared for climbing... We are talking about 4.10 rear end
09-04-2013 08:27 AM
338Lapua It really depends on what you want to do with the jeep. I bought the 4:10's becasue I knew I was going to 35's and did nto want to regear. She does buzzy on the highway at 80MPH...3000 RPMs....70MPH is 2500 RPMs. I usually drive 65 to keep it around 2000RPM's.

The 3.6L can spin the RPM's....not like the older pushrod motors. It is not a good comparison to a 4 banger Civic at 3000 RPMs. The 3.6L has alot more rotating mass. I would not run her on a road trip all day at 3000 RPM's ...but that is just me, mileage will be awful. We do abuse the crap out of these engines during durability testing and they hold up very well.

I have no regrets on the 4:10's .....I knew what i was getting when i went in and ordered. I get around 17 MPG with the stock tires.
09-04-2013 12:21 AM
macaw1us Went to two Dealers today and drove two Rubicons.
Both were 5 speed autos, the one with the 3.73 in 4Lo was going 6 mph at 2000rpm,
the 4,10 was 3 1/2 mph at 2000rpm
09-03-2013 09:04 PM
Jstraw I have 4.10 and was getting lousy gas mileage... Then I bought a set of sahara rims and tires, less then 500 miles of wear, my mileage increased to 20 hwy. it isn't the gears, it's the tires.
09-02-2013 09:12 PM
jk'n Oh yah, towing with the 4.1s near the weight limit for the jeep is also a plus compared to the 3.73s.
09-02-2013 09:08 PM
jk'n I had a Sahara with 3.73 and now two Rubicons with 4.1. I like the peppiness of the 4.1 in the Rubicon. In the two door is most noticeable. My 4 door sahara seemed sluggish compared to the 4 door Rubicon. I'm happy with both Rubicons. I average around 18-19 mpg since new and the two door has 60K on it and the four door has 85K on it. The MPG hasn't varied much since new. I have stock suspension and tires. It doesn't see much trail use but I don't care, I bought it for its capabilities in ALL situations including trails and a lot of winter driving in the snow. They do awesome in both situations.
09-02-2013 07:34 PM
scuba_steve Can't say that I have driven both extensively. I have the factory 4.10 gearing on my 2013 JKR auto trans...and it is a blast to drive. It blows away my TJ and YJ. I step on it at a dead stop and it just takes off. It also has way more pickup driving at speed than my old jeeps. Gas mileage with stock tires is not fantastic (16 or so around town with a heavy foot), but that's not my priority.
09-02-2013 06:31 PM
123Jato I get 11 mpg with my 35's on 4.10's
09-02-2013 06:23 PM
4x4n Cant believe all of the 4.10's kill gas mileage talk. I have had 3.73 in to 2 different JK's now and get around 15MPG with both. (Maybe my lift and tires have something to do with that) Dont think it would be much different with the 4.10's. If you will never want to go with bigger tires or a lift, you'll be just fine with the 3.73's, but I would go for the 4.10.
09-02-2013 12:14 PM
badtux I went with the 4.10. It drops the MPG by about 2 mpg both city and highway, but makes my Wrangler Rubicon w/automatic transmission feel like a friggin' Ferrari. And when I go to 35" tires, it means I don't have to re-gear, though my Jeep will go back to feeling like a Jeep at that point.

Don't listen to the "it'll make the engine scream" moron, at 80mph the engine is at around 3000 RPM with the 4.10 gearing and stock 32.4" tires, at 70mph it's well under 3000 RPM. The 5-speed automatic has a pretty tall overdrive. My mom's old Honda Civic did that many RPM at 70mph and would do it for days on end, we finally sold that car with 250,000 miles on it and my brother reports that the person he sold it to currently has 310,000 miles on it.
09-02-2013 11:21 AM
NW Rubicon For your intended use, it seems 3.73 is a better choice. You're driving habits are like the majority of people that buy a Rubicon. Jeep choose 3.73 with auto as standard, for a reason.
09-02-2013 10:59 AM
JK Coaster The best way to resolve gearing issues in your new rig is to thoroughly test drive the options at various dealers. There have been several threads where 2013 Rubi owners with automatics were expecting 4.10s and their rigs were built with 3.73. instead. As I remember, those who were going to daily drive generally kept them, but they did there homework on the test circuit.

Some had to drive a ways to find the right rig to demo. In my part of the county many dealers have a rig with 33's or 35''s somewhere on the lot. The only way to know for sure if you will like the gearing/tire combo is to try it.

In your case you have to move fast. I would be surprised if your salesman at your dealer doesn't at least have a 3.73 vs. 4.10 set of test vehicles with stock tires sitting on lot. You will find at 70 mph the difference, as I remember, is only about 150-200 rpm, but check this, and their relative acceleration performance with your own observation - then decide.
09-02-2013 10:37 AM
123Jato
Quote:
Originally Posted by CAWillie View Post
Guys....what's the final conclusion? Read all of this thread and you guys seem split.

I am ordering in 7-9 days...2014 2 door Rubicon. Auto trans. Dealer was going over options with me and talked me out of 4.10. Said the 3.73 was better choice. I would kill my mileage by 4-5 miles..ie end up getting 13 mpg instead of 17-18...also said it would run the engine harder driving on highways....not worth it. So I listened to him and went with 3.73. But, the order doesn't go out until 9-11th because I am waiting on Copperhead Pearl paint option.

Now I am reading don't get a Rubicon unless you get 4.10 rear end. 4.10 makes Jeep seem like "hot rod" around town.........only 1mpg difference....only 200-300 rpms difference....barely notice it, etc.

Which one is the better choice? If it really doesn't make that big an impact on mileage and engine noise on post-12 model Jeeps, then why not get it for the fun factor?

Help me out, I want advise on this before the order gets placed in a week. I still have time to change mine before the order gets placed. Thanks
Get the 4.10. I could not imagine driving with 3.73 even when I had 33's but now I am pushing it with 35's with the 4.10's
09-02-2013 10:32 AM
CAWillie Guys....what's the final conclusion? Read all of this thread and you guys seem split.

I am ordering in 7-9 days...2014 2 door Rubicon. Auto trans. Dealer was going over options with me and talked me out of 4.10. Said the 3.73 was better choice. I would kill my mileage by 4-5 miles..ie end up getting 13 mpg instead of 17-18...also said it would run the engine harder driving on highways....not worth it. So I listened to him and went with 3.73. But, the order doesn't go out until 9-11th because I am waiting on Copperhead Pearl paint option.

Now I am reading don't get a Rubicon unless you get 4.10 rear end. 4.10 makes Jeep seem like "hot rod" around town.........only 1mpg difference....only 200-300 rpms difference....barely notice it, etc.

Which one is the better choice? If it really doesn't make that big an impact on mileage and engine noise on post-12 model Jeeps, then why not get it for the fun factor?

Help me out, I want advise on this before the order gets placed in a week. I still have time to change mine before the order gets placed. Thanks
12-12-2011 09:28 PM
Georgia
Quote:
Originally Posted by blackforestgreen View Post
yup, stole it sort of, didn't know it was on, still appropriate though. lol

Oh, Hi Val!
12-12-2011 09:24 PM
blackforestgreen
Quote:
Originally Posted by Georgia View Post
I'm pretty sure that was Val Kilmer in "Red Planet"...playing on SyFy right now.
yup, stole it sort of, didn't know it was on, still appropriate though. lol
12-12-2011 07:21 PM
JIMBOX And therein lies the crux !


Quote:
Originally Posted by panthermark View Post
The gears can be swapped on 2012's if you want. The limp mode issue was fixed about two months ago.

As far as comparisons go....the only thing you can look at is final drive ratio (which I what I were prefer instead of axle ratio).

The problem is that not only are you dealing with two different tranny's....but also two different engines as well.

There is a ton of knowledge here on the 42RLE and the 3.8 where you need to be in the powerband......but there isn't nearly as much detailed knowledge on the 3.6.
Straight to the heart of the matter-

JIMBO
12-12-2011 07:14 PM
panthermark
Quote:
Originally Posted by blackforestgreen View Post
i have been thinking about this thread and saying the new rubis are fine with 3.73 rears and it is just possible i might be wrong. especially since it turns out it may be awhile before we can do gear swaps in the 2012s. with the new auto drivetrain, is there a way to convert, x ratio and new drivetrain is equal to x ratio in the old drive train. 07 t0 11 jk models.

i had hoped and believed this day would never come, but seems in 1971 my freshman year of high school, my algebra teacher said "some day you are going to have to know how to do this ....." i guess since i can't do the math ,today is the day.
The gears can be swapped on 2012's if you want. The limp mode issue was fixed about two months ago.

As far as comparisons go....the only thing you can look at is final drive ratio (which I what I were prefer instead of axle ratio).

The problem is that not only are you dealing with two different tranny's....but also two different engines as well.

There is a ton of knowledge here on the 42RLE and the 3.8 where you need to be in the powerband......but there isn't nearly as much detailed knowledge on the 3.6.
12-12-2011 07:07 PM
JIMBOX Heh Heh-yeah, of course--semantics and it is purely a matter of RPM/gear ratio for applied power/torgue-and


Quote:
Originally Posted by i82much View Post
You can absolutely increase torque without changing power, that is *exactly* what increasing the gear ratio does.

You can absolutely increase power without increasing torque - just apply the same amount of torque faster.
All I can say is my gear/selection, seems to have found the best of the combos-

Smokemifyougotem

JIMBO
12-12-2011 07:03 PM
Georgia
Quote:
Originally Posted by blackforestgreen View Post
i had hoped and believed this day would never come, but seems in 1971 my freshman year of high school, my algebra teacher said "some day you are going to have to know how to do this ....." i guess since i can't do the math ,today is the day.
I'm pretty sure that was Val Kilmer in "Red Planet"...playing on SyFy right now.
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