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40's on 2.5 lift

22K views 35 replies 19 participants last post by  sportcoupe 
#1 ·
I have read a few post on here about jeeples running 40's with a 2.5 inch lift and cut fenders, I like the idea of low COG, but what all is involved in this set up.
I see a re gear and chromoly axle shafts but what else would be needed.
If you are running this set up please chime in and post pics.
I have a 2011 JK rubicon.
 
#2 ·
I think you would be hard-pressed to find anyone on here who thinks 2.5" lifts will be sufficient with 40's. Your suspension uptravel would be pretty limited. I ran 37's, 2.5" lift, and flat fenders for awhile. It was OK off-road, but I switched to MetalCloak's 3.5" springs which make things much more doable off-road with 37's.
 
#5 ·
Hi, I've posted this a few times and it seems to hold water...

The first visit I made a few years ago to a very reputable Jeep shop here in Phoenix went like this:

I'd like to know what it takes to run 40's? The reply... Write me a check for $25k and come back in a week to pick up your new rock crawler. Nothing I have learned since has made that response any less accurate.

Most say that you need 60's to run 40's and that is almost $15k right there.
 
#14 ·
Hi, I've posted this a few times and it seems to hold water...

The first visit I made a few years ago to a very reputable Jeep shop here in Phoenix went like this:

I'd like to know what it takes to run 40's? The reply... Write me a check for $25k and come back in a week to pick up your new rock crawler. Nothing I have learned since has made that response any less
25k to run 40s? That's funny. Could you spend that much? Sure. With fully dressed pro rock 80/60, hydro steer, double throw down coil over setup/ Evo lever rear and long arms. Basically your cookie cutter I've got too much money here's my new jeep build. They are dime a dozen here.

Sell the rubi axles, build a sterling rear and 60 front and you are in for 6k on the high end with lockers. 3.5-4" coil lift with arms. 2k. Drive shafts 1k, complete hydro steering 2k. 40s 2k ish. Add 1500 for wheels due to the bolt pattern change and Total is 12.5k minus whatever you sell rubi axles for. Most won't put in the work to build your own axles, it's easier to swipe plastic. But to say the only way to safely run 40s is a 25k check is a bit obsurd in my opinion.
 
#6 ·
WILLYSDAVE, none of my jeeps have any idea where the Mall is, I do a lot of wheeling and care less about looks just practical usability. just wonder if this is a solution to more ground clearance with a low COG
 
#8 ·
I think that concept is good up to 37's. A 2.5 premium, like RK or MC, with flats and 37's is an awesome rig and doable on a modded stock axles, LCoG set up.
 
#7 ·
^^ Awesome responses!! :thumb:



IMO:

To make what you have work:
Front & rear axle shafts
Ball Joints
Gearing
C gussets, full truss if wheeling
Proper bump stops, you won't get much flex
Hydro steer if wheeling
Fenders (or cut factory)
Wheels
Tires
^Probably about 15-18k of parts/work


To do correctly:
D60 front & rear
Wheels
Tires
Bump stops
Hydro steer
^Probably about 20 - 25k of parts/work


IMO

Good luck and have fun!!
 
#13 ·
I regularly wheel with a local who runs 40's on his 2008 4dr rubicon with 4.5" lift (IIRC)
Even that is a fairly LCOG build and it took alot of work to get it to work for him, his related mods are hydro assist, 5.38's, rcv's, sleeves gussets and truss otherwise stock Rubi axles. For his type of wheeling it works well although he knows his axles are still a weak point but he's been running that way for over 4 years now.
Having said that I think 40's are a bit much for a 2dr for 99% of people, 37's on a similar build is much easier to do and helps keep stability in check on a short 2dr. Just my $.02
 
#17 ·
I don't see how you could run 40's with only 2.5" of lift. Prior to swapping out suspension, I had 2.5" AEV lift and put on 37's. I got quite a bit of rubbing just from turning. I could've adjusted the steering stops.... Not to mention the tires looked stuffed under there even with flat fenders. I would've rubbed like crazy going off road with that set up. And that was with 37's.
 
#20 ·
wheeled with this guy in moab his was 2.5" RK stock mod and mtr 37's. He was still rocking a D30 and said he had wheeled a lot and by his skills he was not lying. He claimed lots of his group was running D30's with no issues.
 
#21 ·
I run 37s on RK 2.5 X Factor. I do not "rub like crazy" and wheel the crap out of it. My only minor rub is grazing the stickers on the front control arms at absolute full lock - BUT short of a custom arms and lift, way low backspace (which puts even more stress on knuckles and so on) and narrower tires (Nittos run wide), you are always going to rub somewhere. If its not the control arms, it will be the frame or body. Pick your poison. Anyone who runs 12.5 or wider rubs somewhere at full stuff. If they say they don't, they aren't wheeling it hard enough. The control arm stickers can take it.
 

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#22 ·
The bigger issue there is the RK Control arms, the bend in them is made upwards for ground clearance rather than inward like the factory arms for tire clearance, my 35's just kiss my RK arms as well
 
#24 ·
Synergy control arms have both an upward and an inward bend to them. Their design leaves a little more tire clearance than some other brands. Teraflex arms bend inward, and so do BDS arms, which also allow for more tire clearance.
 
#27 ·
#29 ·
You can do it, the question you will have to ask is how much cutting are you comfortable with? Also how much do you hate up travel to do it on such a low lift? I understand the low center of gravity idea, hence why I am on a 3" lift and running 37's. But I would hate to sacrifice all of my up travel in the name of LCG.
 
#30 ·
I think that's been the consensus so far, it's doable with 37's and a 2.5 and too many sacrifices to go 40's at that height.
 
#33 ·
Nice. I'm running the same springs on my 2 door with half inch spacers front and rear with 2" inch bumps all around. Couldn't be happier I think it's the perfect height for 37s. Getting all 10" of travel out of my rancho shocks as well due to bumpstop height and shock bracket relocation
 
#34 ·
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