[tbas01]

Ok guys...just bought the new Unlimited yesterday and am already thinking about what needs changing. Pardon the newb questions, but I'm a newb so forgive me.

I want to put a 2.5" or 3" lift on it and some bigger tires...probably 33in. What size wheels is best for that tire size (currently have 18s but want to replace them). How bad will those tires throw off my speedo? Can I get it re-calibrated?

I knew I was going to have to change out the gears so I just got the standard 3.23 gears. If I change to 4.11, how will that affect my highway driving? Also, can someone post a link here to exactly what I need to change out the gears? Any guess as to how much it will cost to install new gears?

Thanks in advance!

[hig4s]

You don't need a lift at all on a JK for 33s,,, even 35s will fit but will rub if you do any wheeling or tight turns. as far as gears, I have heard from others that with 33s or 35s the stock 3.21 gearing make 6th on the manual too high. The Rubicon comes standard with 4.10 and 255/75 17 (10 x 32s). gas mileage on any of the JKs is only a couple of miles per gallon different.. Remember, once you hit about 65mph you are pushing a brick through the wind and gas mileage will be bad.

You should be able to go to a 265/75 16 (10.5 x 31.5s) or a 265/75 17 (10.5 x 32s) without any problem stock. You might even be able to go 285/75 16 (11.2 x 32.8s) height is OK but not sure about the width on those, might need spacers or wheels with less back spacing to fit. With the right wheel backspacing I understand you can go 12.5 inch wide.

I figure I'm keeping my JK stock until I wear out the stock tires then I will get one of the 16in tires I mentioned, Probably the 285s. I have the 3.73 gears so I should be OK there. And if I do lift at all it will probably be a 2" just to off set the weight when I add steel off road bumpers and a winch.

[SecondTJ]

Originally Posted by tbas01

I want to put a 2.5" or 3" lift on it and some bigger tires...probably 33in. How bad will those tires throw off my speedo? Can I get it re-calibrated?

A 2-3" lift with 33's is a nice start. I'm not sure how much it will throw it off. Yes you can get it re-calibrated. You need a special tool though, its like $300. Its best to find somebody with one and just borrow it.

Originally Posted by tbas01

Also, can someone post a link here to exactly what I need to change out the gears? Any guess as to how much it will cost to install new gears?

Gears plus install kits will run you about $600

http://www.northridge4x4.com/proddetail.php?prod=SA-JK-GEARS-INSTALL

To get them installed will run you about $500-700. Labor is typically between $250-350 per axle.

[tbas01]

SecondTJ, thanks for the link. I don't expect to go any bigger than 4.10s...hopefully that'll be plenty of power.

[SecondTJ]

Originally Posted by tbas01

SecondTJ, thanks for the link. I don't expect to go any bigger than 4.10s...hopefully that'll be plenty of power.

The only place you are going to find 4.10 gears are from '07 owners who have re-geared and have their used stock gears for sale.

Re-gearing is not something that you want to pay to do twice, because of its cost.

[Prot]

If you are going to go with 33's, then get 4.56 gears. If you are going to go with 35's, then get 5.13 gears, especially if it is an automatic transmission. The percentage of increase between your stock tire diameter and the replacement tire diameter is what your speedometer will be off. The dealer can flash up to 32" tire size, since that is what the Rubicon and Sahara is. Beyond that, you need to get an Accupro programmer to input your tire size and gear ratio. They run around $200 or you can borrow one from someone. I think ge2 is still loaning his out and has made its way across the country several times.

See my signature on what I am running for tires and gears. I have the automatic and it's a perfect setup.

[tbas01]

Prot, thanks for chiming in. How does your ride behave on the highway? I'm in this more for looks than off-road functionality, although I'll do some trail riding every now and then. I put a ton of miles on my vehicles and this is my new DD so it needs to ride nicely at 75mph.

My only point of reference with gears is what a 4.11 setup does to a muscle car (I used to have a 64 Chevelle with a 454 and 500hp), and I don't want to be pushing 4k rpm at 60mph.

Your rig has the look I'm going for so I guess I'll go with 35's....as long as it won't render my ride un-drivable on the highway. I do have an auto trans...

There is a place right near me that does nothing but jeep mods....think they'd have the programmer?

[Prot]

The 5.13's enchanced onroad capability as well as offroad. Basically, you have more power available to pass someone or if traffic is heavy and you need to quickly get onto the highway, the gearing gives you the get up and go to do it safely. Ride will be affected by shock and tire selection. I'm OK with my setup, but I'm looking to go with better shocks, but have not decided on what to get. The Black Diamond 3" lift is good, but I think the shocks that came with it leave something to be desired. I find on the highway, if I go through a series of bumps like a washboard, they don't handle it very well and I sometimes get bucking horse effect. I talked to a very good shop about it and they were of the same opinion I was in that the black diamond shocks are merely adequate. Tires with high load ratings also contribute to a harsh ride, but the BFG are good. I think Goodyear Silent Armors would be a better choice for highways, but they were out of the question for me because my driveway is 800' long and is just one giant mud hole despite many efforts over the years with shells, limestone etc. I needed a tire that can get me out of the mud and still be quiet and a reasonable choice for in town and occassional interstate driving. The BFG's were a nice compromise I think. Ideally, I would like Bilstein 5150 shocks, but they do not make any specifically for the JK at this time. I have been looking at Fox Racing Adjustable shocks, but at $250 EACH, they are just not worth it. I could see paying that for a pair, but I'm not paying $1,000 for a set of shocks.

My Sahara came with 4.10's since it is a 07 model. These were OK for the stock 32" tires and I ran them with the 35's for a time, but found my cruise control sucked when traveling 65 MPH. The automatic didn't seem to shift at the right points either. Now, the cruise is great and the transmission gets it right every time.

The programmer is fairly new since it's for the JK, so the chances of them having it to use on your JK is pretty slim, but it doesn't hurt to ask.

5.13's did not raise my rpm a ridiculous amount. It's around 500 RPM higher than 4.10's were. You don't hear the engine revving or working hard when going 70 mph. If I put my foot in it and it downshifts, it does rev, but not into the red line and it actually sounds pretty cool. It sounds better than when I would have to do that with the 4.10's. Once it shifts back up, everything is quiet again. This engine does not shake itself to pieces at high rpm's like my 95 YJ with a 4.0L did.

By all means, get the 4 door if you can afford it. Not only for the more room for people, but more room for cargo and a smoother rider due to the longer wheel base.

The gears with the install kits were $700 and had everything to do both axles. Labor was $250 or $300 per axle.

[hig4s]

Originally Posted by Prot

If you are going to go with 33's, then get 4.56 gears. If you are going to go with 35's, then get 5.13 gears, especially if it is an automatic transmission. The percentage of increase between your stock tire diameter and the replacement tire diameter is what your speedometer will be off. The dealer can flash up to 32" tire size, since that is what the Rubicon and Sahara is. Beyond that, you need to get an Accupro programmer to input your tire size and gear ratio. They run around $200 or you can borrow one from someone. I think ge2 is still loaning his out and has made its way across the country several times.

See my signature on what I am running for tires and gears. I have the automatic and it's a perfect setup.

And what is your gas mileage like with the 5.13s. If it doesn't make it a lot worse I can see it, especially with an auto.

But a manual, has 6 gears, just pick the one you need when accelerating and 6th is suppose to be an over drive, not for passing. I have 3.73 rear and while my stock tires are only 29s on flat ground I rarely use 3rd or 5th and just skip shift passed them. I can also go to 6th at 40 mph.. I plan to up to 32s or 33s and do not expect to have to re-gear. Certainly I will no longer be able to skip shift or go to 6th at 40mph, but I don't expect problems.. Of course I only do mild wheeling, mostly sand, so I don't need the extra low gearing for rock crawling.

[Prot]

I'm getting 3 mpg better with 5.13 gears and 35's compared to 4.10 gears and 35's. The lighter load on the engine is the reason. It is not as good as stock 32's with 4.10's. When my Accupro programmer comes in, I'll have better, more accurate numbers. Right now, I'm just talking in relative terms.

The improvements are across the board when regearing, so it's not really the same thing as using a manual transmission in one lower gear than normal. But yeah, the automatic transmission saw a huge benefit from regearing. I can't see running 35's with 3.21 gearing with either transmission, especially the automatic. I also believe the lower gearing with oversize tires will contribute to the longevity of the automatic transmission. I was a non-believer in regearing until I actually did it. Now, I can't believe I waited as long as I did to do it.

[ironbutt]

if i had it to do again, i would go with 4.56. my jk is my dd and i do quite a bit of highway driving. my rpm's went up from 2200 to 2800 @ 70 mph when i changed from 3.21/29 to 4.88/35. 6th gear is a requirement now on the highway, and not as an overdrive. auto's may be different, but if this is mainly a dd highway vehicle, i think that 4.56 would be plenty for either auto or man.

[tbas01]

Prot and Ironbut, do your rigs fit in a standard height garage? I'm starting to worry that with a 3" lift and 35s, i'm not gonna get in.

Anyone else know?

[Prot]

I don't have a garage. I think it would though. It's really not all that tall. Figure your stock height, add 4" for the lift (most lifts will lift it higher than advertised), and add 2" for the added tire height (remember, radius, not diameter is what is important here).

[muttytruckster]

With all this talk, I am curious as to those with manual trans what is your MPG with 35s and if you regeared, what did you change to and from?

[ironbutt]

Originally Posted by tbas01

Prot and Ironbut, do your rigs fit in a standard height garage? I'm starting to worry that with a 3" lift and 35s, i'm not gonna get in.

Anyone else know?

i measure 78 inches at the highest point and it does fit in the garage.

three car garage...JK, TJ, Excursion in the garage...corvette in the driveway.