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Discussion Starter #1
Ok So I have had my YJ for just over a month now. I have taken it out and begining to put some trail miles on it and 1 thing is for certain to me, it is geared TO HIGH. 1st gear low is still to fast for navigating rocks and even smaller ledges, you constantly are feathering the clutch. Its either clutch it or kill it when trying to crawl and navigate the rocks, or send it and bounce all over creation. That being said, Im running 33s, AX15 with a gear ratio 3.07

My question is what would be best for Moderate rocky trails and yet daily drive. Is there a good medium? Any advice/input is welcome.
 

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Ok, so you wheel it, have a ax15, you want 4.56 or 4.88 gears. I myself would choose 4.88 for your limited description of the type of wheeling you do. 4.88 would allow you to go to 35" tires in the future with no problem.
 
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Also, a hand (thumb throttle) throttle is handy for rock crawling. Lets you set the idle up to keep forward momentum smoother
 
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I ran 4.11 gears with my 4.0/NV4500 and 33's and i liked it. I cant compare crawling ability because NV4500 is geared much lower but it also has a higher overdrive. I just know i was happy with it and it good pretty good gas mileage with that setup.

Right now i have 35's and 4.88's and it screams at 75MPH and i get absolutely horrible gas mileage. So i would definitely not run 4.88's on 33's if you daily this jeep and want good gas mileage because you are not going to get it.
 

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Ok So I have had my YJ for just over a month now. I have taken it out and begining to put some trail miles on it and 1 thing is for certain to me, it is geared TO HIGH. 1st gear low is still to fast for navigating rocks and even smaller ledges, you constantly are feathering the clutch. Its either clutch it or kill it when trying to crawl and navigate the rocks, or send it and bounce all over creation. That being said, Im running 33s, AX15 with a gear ratio 3.07




My question is what would be best for Moderate rocky trails and yet daily drive. Is there a good medium? Any advice/input is welcome.

What size tire are you going to run going forward? How much road time to off-road percentage are you expecting?
 

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Discussion Starter #6
Flex, Id say 75% would be easy off roading with the occasional moderate stuff. The problem is, I never intended to be doing any rock crawling or moderate off roading. It was for running gravel and dirt roads, chasing the river systems and fishing....and yet,,,here we are! I might one day go to 35s but Im happy right now with the 33s. I would like to be able to drive around town but I can skip the highway if need be.
 

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Flex, Id say 75% would be easy off roading with the occasional moderate stuff. The problem is, I never intended to be doing any rock crawling or moderate off roading. It was for running gravel and dirt roads, chasing the river systems and fishing....and yet,,,here we are! I might one day go to 35s but Im happy right now with the 33s. I would like to be able to drive around town but I can skip the highway if need be.

If thats the case you definitely want to stay far away from 4.88's. Thats what I'm running on my new rig with 37's (different engine and an automatic, set up for rock and roll).


33's on the YJ with the right lift will give you 1000 smiles. If thats your decision you probably want to stay between 4.10 and 4.56. Manual and automatic makes a big difference. My 4.10's on my manual TJ was a good set up with the 33's... 5th gear was highways only.
 
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Yep 33's 4.0 ax15, if you ever drive it on the road go w 4.10 or 4.56.... I have 4.10 w that setup and consider it perfect.. 4.56 would crawl VERY VERY slightly better but push the rpm's higher than I want on the highway....

Case in point, a buddy of mine just got a deal on 4.56 axles for his 4.0 5 speed tj on 33's.... they are a HUGE improvement over his previous 3.07's but after a couple weeks of driving to work w em he is gonna swap em for a set of 4.10 axles....
 

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Although I have done it for people in the past, I would never do 4.10’s on a 4.0/AX-15 equipped Jeep running a 33” tire, it simply is not enough gear to run it in the power band where it belongs (on the street), and the crawl ratio with a 2.72 Low is insufficient to say the least, for anything other than moderate ‘wheeling.

On my “keeper” YJ I installed .56’s with the Dana 44 swap, and even loaded to the gills on long road trips it was geared near perfect with the 33’s, and I drive hard.

I have since installed 35’s and it is still geared ok, but I have another MJ 44 waiting in the wings so may do a swap, do .88’s, and use my current diffs. in the next build that I plan on running 33’s on.

Go to ring-pinion dot com and play with the gear ratio/RPM calculators there. Punch in the OEM tire height (keep in mind the largest OEM tire size was a 225/75/15, approximately 28” OAH) with a 3.07 gear and a manual O.D. Trans. Then do the same with 4.56’s and a 33” tall tire. Pick a baseline speed (most people use 65 as an example) and check the RPM at each combination change. The results may surprise you.

Not sure where you are in this fine country, but if you are in So Cal I have a number of 4.0/AX-15 YJ’s you are welcome to drive, in just about every tire/gear combo from 4.10/31” to 4.88/35” (including a couple of 4.56/33”). Seeing is believing.
 

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Yep 33's 4.0 ax15, if you ever drive it on the road go w 4.10 or 4.56.... I have 4.10 w that setup and consider it perfect.. 4.56 would crawl VERY VERY slightly better but push the rpm's higher than I want on the highway....

Case in point, a buddy of mine just got a deal on 4.56 axles for his 4.0 5 speed tj on 33's.... they are a HUGE improvement over his previous 3.07's but after a couple weeks of driving to work w em he is gonna swap em for a set of 4.10 axles....



I believe you mean Gears not axles... Just don't want to confuse anyone trying to improve their knowledge base.
 

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No I mean axles... as in complete axle assemblies....
 

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Alright, moving on.....
Let's get back on topic and talk gear ratios
 

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Fire fish should stay between 4.10 and 4.56 for his use and set up.. I'm at 4.88 with 37's for versatility with emphasis on crawling, harder trails and it's the strongest gearing for the D44 housing. Straight crawlers/heavy off-road should be above 5 (assuming they are at 35's or above).
 

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Discussion Starter #16
I found a set, front and rear axles off of a YJ for $800 but they are 3.73. According to the "formula" this is what I need but I think I want to hold out for the 4.10s
 

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I found a set, front and rear axles off of a YJ for $800 but they are 3.73. According to the "formula" this is what I need but I think I want to hold out for the 4.10s

That's telling you 3.73 based on the Jeeps original design. By creating a new design and specifying the likelihood of usage you now have a reason to "re"design your Jeep and gearing. Otherwise this entire site and world of Jeep enthusiasts wouldn't be here..


"Bad seed is the robbery of the worst kind: for your pocket-book not only suffers by it, but your preparations are lost and a season passes away unimproved."


If you move your questions to the tech section, you will find more information in regards to your options.


Do what makes you happy and don't forget to wave..


Jeff B.
 
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I found a set, front and rear axles off of a YJ for $800 but they are 3.73. According to the "formula", this is what I need but I think I want to hold out for the 4.10s
You would be a fool to go with 3.73 gears. 4.56 is the minimum for the AX15 with 33" tire.
 

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3.73 for free would be worth it but not for $800
 
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