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Discussion Starter #1
OK here we go;

I'm at the point where I am seriously thinking of a re-gear.

I have BFG K02's @ 34x10.5(33.2" actual measurement) on 3.21 gearing on my JK 2-door. I may or may not go,at some distant point in the future to 35" tires(when the 34x10.5's wear out),and if so, they would be BFG K02's and I know they run a bit under 35.

Now I know that the wrangler isn't a fuel econo vehicle,but such that it is, I'd like to keep the DD fuel eco. as good as I can get it,right now I get 19 to 21 MPG highway,and just wonder how the two different gear sets will affect the DD fuel consumption part of the equation. My thinking is the 4.10 gears might improve fuel economy slightly(being right in the sweet spot) and 4.56 might hurt it...but I'm not 100% sure on this. I run secondary highways 50 to 60 MPH max.....so no 80+MPH for me. Mildly hilly travel on road for DD travel...and off road mostly forestry service roads and crown land logging roads.

I'd like more pep on road, and grunt off road,...hence the gearing change.......... so the question is this;

4.56 or 4.10 gears for what I want to accomplish. Just on the RPM chart's that I've looked at, instinctively I'm thinking the 4.10 would be perfect for the size tires I have right now,and strike a perfect balance between off road and DD service. Then again 4.56 might be the way to go and not be to deeply geared for the current tires I have.......and perfect for the 35" tires I may get in the future...although I've heard 4.10 gears work good on 35" tires.:pullinghair:

It looks to me like the 4.10 gear set @ 33" tire will get you a gain of 500 RPM...while the 4.56 will garner a 798 RPM gain...that is, in both cases, in top gear(auto) @ 70 MPH...from 3.21 gearing.

Hep me make this decision...please!!! LOL!!

Bill.
 

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4.10 is good "Offroad grunt gearing"...for stock 32 inch tires (aka stock Rubicon gearing).

4.56 will give you decent "grunt" on your 34s, but you will lose that if you move up to 35s (35s I would recommend 4.88). There is only less than 1/2 inch clearance difference you realize between a 34 and 35.

The savings in wear and tear on your engine being properly geared will compensate for whatever mpg difference there is. It is a Jeep - mpg will never be good, and engines/transmissions cost way more to repair than the few cents in gas.
 

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Discussion Starter #3
striking the balance.....

4.10 is good "Offroad grunt gearing"...for stock 32 inch tires (aka stock Rubicon gearing).

4.56 will give you decent "grunt" on your 34s, but you will lose that if you move up to 35s (35s I would recommend 4.88). There is only less than 1/2 inch clearance difference you realize between a 34 and 35.

The savings in wear and tear on your engine being properly geared will compensate for whatever mpg difference there is. It is a Jeep - mpg will never be good, and engines/transmissions cost way more to repair than the few cents in gas.
Thanks for the response.

The thing is the 34x10.5 K02's aren't actually 34" I measured the spare when new and they are 33.2".

What I'm wondering is will 4.56 be to deeply geared at the actual 33" tire measurement for a DD....or will I regret going to 4.10 if and when I do eventually go to 35" tires when the 34x10.5's wear out.

Again I run secondary highways and dirt roads where I typically go 40 to 50-55 MPH. Rarely do I run on the major highways that are 60 MPH max. the rare occasion that I do hit these highways I stick to the speed limit 60 MPH.

I know the 4.56 gear would be awesome off road as would the 4.10....I'm just trying to strike a balance between off road gearing and DD use. Everything is a compromise to strike the balance-sweet spot is my goal here. If my jeep was a dedicated off roader....well then the choice would be clear.

I don't want the engine RPM to be to high and sucking down fuel excessively on highway,while cruising around.

Anyone experience 4.56 on 33" tires as a DD....did you regret doing this or was it acceptable as a DD and sometime off road fun vehicle???????

Or conversely anyone get 4.10 gears on 33" tires then down the road get 35" tires and how did that work out as DD-off roader???
 

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It's just my opinion, but I say go big, or go home.

I honestly don't think that the difference in rpms on the interstate or the secondary roads that you drive on regularly would be that large, yet there would be a significant difference in they "butt dyno effect" with the deeper gears. It sounds to me like you're over thinking it.

It's cheaper to spend the money once, than it is to have to go back and do it all over again because you didn't go deep enough the first time.

good luck

Exco
 

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Currently running 35" KO2s (they measure 33.5" or something around there is what I have dialed in using my FlashCal) with a 4.56 on a 6-speed. Just took a two hour trip on secondary highways where I was going about 60 to 65 MPH and got 18 MPG. If I travel 70 to 75 MPH, it drops to the low 17s. City (suburban) driving is in the middle to high 16s. Driving 75 to 80 MPH could be middle 14s to high 15s depending on how much wind and the elevation. Hope this helps, I may consider going to 37" KO2s at some point now that I know they run smaller.


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I believe 4.56 to be the perfect gear set for 34s and fine for 35s. 4.10, as MMC pointed out, were deemed to be perfect for the much smaller stock 32s. And even though your 34s measure 33.2, that's the case with every tire out there.

I run 34" KM2s (285/75) and they measured a little bigger than yours when new (they were 33.25 with the Jeep's weight on them, and you say your unweighted spare is that size). To me 4.56 is a perfect gear set for them, but bear in mind I have a 2-door 6M; I don't know what diff a 4-door or 5A trans might make, as gearing is different in the two transmissions.

I do know that with my trail tires on (35.5" with Jeep on them) the 4.56 is adequate for sure but if I were running them full-time I'd prefer 4.88. I think that with 315s or 35s (actually measuring around 34") I'd be happy with 4.56. I'll find out soon enough -- I have a set of KO2s in 315/70 I'm getting mounted this week.
 

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Discussion Starter #7
Thanks everyone..

Thanks for the input...and yeah I'm probably overthinking it for sure LOL!!

I just want to make the right decision,and improve all aspects of drive-ability both on and off road.

I'm leaning toward the 4.56 gears...with the "do it once"...line of thinking,with regards to down the road and 35's.

I know I'd really like the "seat of the pants" dyno,with the improved acceleration and torque through all the gears.

The deeper 4.56 gears will also help move the extra weight that I have in the way of, steel bumpers front and back, and winch...wheels and tires.

I have a feeling that fuel eco will stay the same if not improve,just by way of the engine and trans working optimally in all gears and shifts with less or no lugging stresses....and just the way that I drive and where I drive.

More comments welcome.
 

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I run Toyo 34/10.50s, that I have a hard time believing are smaller than your KO2s, but they measure 33" on the head. I run stock 4.10 with a 6MT. I would say I am at the limit of decent gearing. No plans to go larger on tires for me. I want to keep with the stock 4.10 D44. If I was getting out my checkbook to pay for gearing and ever thought I was going to get 35's the choice would be between 4.56 and 4.88. If it was a hi-way cruiser then 4.56 but any stop and go and any off road I would get 4.88s.

I read about MPGs and re-gearing and I think there is too much emphasis on that here on WF. Driving style has so much more impact than gearing. If you want to get good mileage drive more conservative...
 

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So much good info here.

I'm in a similar boat. I have stock axles, 3.21's, and I shifted from stock tires (when I bought it), to now am running 33x12.5 tires. It does feel a bit more sluggish, and I almost never hit 6th gear even on highway without overwhelming the engine.

Lately, I've been considering going higher on gear sets.
 

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.....I run secondary highways 50 to 60 MPH max.....so no 80+MPH for me.......
I find that with 4.88 and 35's those speed to be about perfect. You have enough grunt to climb most hills without down shifting into 6th, I have a manual and you can still run 80 if you don't mind 3000 rpms if you are in a hurry. I don't really like running above 70 because of wind noise, I have a soft top. I should say I have my tires set in my TD2 right now a 33.2, but I do have a few miles on these tires now.
 
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Discussion Starter #11
I find that with 4.88 and 35's those speed to be about perfect. You have enough grunt to climb most hills without down shifting into 6th, I have a manual and you can still run 80 if you don't mind 3000 rpms if you are in a hurry. I don't really like running above 70 because of wind noise, I have a soft top. I should say I have my tires set in my TD2 right now a 33.2, but I do have a few miles on these tires now.
How about 33's and 4.56 at those speeds???
 

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How about 33's and 4.56 at those speeds???
Go with 4.56's and don't think about this anymore, they'll be fine with that you have now, and anything in between that and a true 35'. if you're going with bigger tires (36's,37's), then do 4.88's.

my 33.5" KO2's with 4.56's put me at 2700rpm at 70mph (A5 Trans), bring that down to 55mph and you'll be in eco mode, or at least super close to it with 33.2" tires.

http://www.youtube.com/watch?v=XnyBoN1Yduo
 
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How about 33's and 4.56 at those speeds???
You would be 150 rpms lower than 4.88's.

So here is the thing. If you are not using 4lo most of the time you are off road then 4.56 would be fine. But if you want to play in the rocks or use 4lo for hill climbing of technical trails then 4.88 is what you want at least. The reason I state this is because you don't have the 4:1 transfer case.

But from the sounds of it you don't do any of that and 4.56 will be a big improvement over what you have.
 
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Discussion Starter #15
WOW guys great info and just the kind of input I am looking for.

rsmwrangler; that is a great video of 70 MPH and the RPM on the exact tire I have,and the 4.56 gear set, yeah that is doable and since I don't run 70MPH on the 400 series highways(that is what they are called here in Ontario)...I run right at the speed limit 100KPH,or 60 MPH on cruise. I'll be heading up to the north country in a few weeks or less(after re-gear) fly fishing trout on the north shore of Lake Superior,and accessing streams and rivers, through logging roads and rough trails. The Trans Canada Highway which I'll be taking for some of the trip is a big highway speed limit 100-KPH,and I'd stick to that. But most are secondary 80-90 KPH highways.

Terry C ; You are correct most of my wheeling is in 4-hi with some 4-lo stuff on(what I consider) tougher sections(hills and what not)..that most here would laugh at,being termed tough,but I'm not that experienced so I take the scenic route and don't like to take chances....choosing to take the easier route,it doesn't take much to make me happy off road. LOL!!

I'm starting to get excited about the re-gear,now that I have some input,and am heading in a direction. Also getting excited about my wheeling-flyfishing trip!!!:thumb:

Thanks guys.
Cheers
Bill.
 

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WOW guys great info and just the kind of input I am looking for.

rsmwrangler; that is a great video of 70 MPH and the RPM on the exact tire I have,and the 4.56 gear set, yeah that is doable and since I don't run 70MPH on the 400 series highways(that is what they are called here in Ontario)...I run right at the speed limit 100KPH,or 60 MPH on cruise. I'll be heading up to the north country in a few weeks or less(after re-gear) fly fishing trout on the north shore of Lake Superior,and accessing streams and rivers, through logging roads and rough trails. The Trans Canada Highway which I'll be taking for some of the trip is a big highway speed limit 100-KPH,and I'd stick to that. But most are secondary 80-90 KPH highways.

Terry C ; You are correct most of my wheeling is in 4-hi with some 4-lo stuff on(what I consider) tougher sections(hills and what not)..that most here would laugh at,being termed tough,but I'm not that experienced so I take the scenic route and don't like to take chances....choosing to take the easier route,it doesn't take much to make me happy off road. LOL!!

I'm starting to get excited about the re-gear,now that I have some input,and am heading in a direction. Also getting excited about my wheeling-flyfishing trip!!!:thumb:

Thanks guys.
Cheers
Bill.
Since i wanted to offer you as much info as possible, here is a picture i took at 60mph this morning, as you mentioned 100kph is more likely your top speed, so that i's 2300rpm, and pretty much spot on for Eco mode. 55mph will be 2100rpm.

Also, you won't have any issues wheeling rocks with 4.56's and the non-rubi tcase on 34" or 35" tires if you wanted, the gear chart defines 2619rpm within the blue range (performance) with a 34 tire, which most 35's are anyways, and 2544rpm in the green range for a 35 tire (and it says this is acceptable range), you won't be able to tell the difference between that rpm, it will read 2600 rpm in the cluster regardless :)I i do Rocky hills with my regular tcase and 4.56's , and see no reason for the crawler ratio in the Rubi, though if i decided later on to do 37's, i'll for sure upgrade my tcase to the Rubi version, along with other things.

20170614_061645 by Wrangler RSM, on Flickr
 
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Go with 4.56's and don't think about this anymore, they'll be fine with that you have now, and anything in between that and a true 35'. if you're going with bigger tires (36's,37's), then do 4.88's.

my 33.5" KO2's with 4.56's put me at 2700rpm at 70mph (A5 Trans), bring that down to 55mph and you'll be in eco mode, or at least super close to it with 33.2" tires.

http://www.youtube.com/watch?v=XnyBoN1Yduo
thanks for sharing the pics and video. helps having a visual reference.

I know this is all subjective and different for everyone, but for you, rsmwrangler, what is the mpg at 70mph in that pretty flat freeway? (ie if you were to reset the mpg for that stretch of the road)
 

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thanks for sharing the pics and video. helps having a visual reference.

I know this is all subjective and different for everyone, but for you, rsmwrangler, what is the mpg at 70mph in that pretty flat freeway? (ie if you were to reset the mpg for that stretch of the road)
High 17's to low 18's, in better terms, i'm able to go anywhere between 330 and 350 miles per tank with about 19.2 gallons of gas.
 

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Discussion Starter #19
Thanks so much rmswrangler great info and vids,and pics. your info persuaded me to go 4.56,most excellent.I thank you.

I've got an appointment at the end of the month(my birthday actually...just worked out that way)....to get the 4.56 gears installed ,and while I'm-they're at it, I'm having an Eaton E locker in the rear end installed,which will be wired right into my sPod....just some more capability in case I get into a tight spot,or plowing through fresh deep snow on the snow roads going in to work in the morning,or just out playing.....in winter of course,LOL!!

Cheers,
Bill.
 

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Thanks so much rmswrangler great info and vids,and pics. your info persuaded me to go 4.56,most excellent.I thank you.

I've got an appointment at the end of the month(my birthday actually...just worked out that way)....to get the 4.56 gears installed ,and while I'm-they're at it, I'm have an Eaton E locker in the rear end installed,which will be wired right into my sPod....just some more capability in case I get into a tight spot,or plowing through fresh deep snow on the snow roads going in to work in the morning,or just out playing.....in winter of course,LOL!!

Cheers,
Bill.
Keep us posted after your 4.56 install. I'm looking into a regear and lockers just like yours.
@rsmwrangler thanks for the details/info.
 
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