Do I understand planman's post correctly?
Thread Starter
JK Newbie
Joined: Feb 2014
Posts: 22
Likes: 0
From: Missouri
Do I understand planman's post correctly?
Some of you may have seen my earlier thread where I discussed lifting our Jeep. https://www.jk-forum.com/forums/modi...-track-297208/
Now I'm considering a different route. Rather than big tires and a lift, I'm considering big tires, flat fenders, and maybe a re-gear. I'm looking for some clarification to make sure that I understand what I've read. We are talking about a 2014 JKU Rubicon X Package with a stock suspension, 3.6 Pentastar, automatic transmission, and 3.73 gearing. I have new 17" wheels on order with a 4.5" backspace and I'm looking at running BFGoodrich KM2s in 35x12.5x17 (closer to 34" real world would be my guess).
Did I read planman's information I quoted above correctly?
With the wheels I have on order (4.5" bs), flat fenders, stock suspension including the stock shocks, and 2" rear bump stops I'm good to go with 35" tires? Basically I would have factory off-road performance but with bigger tires and no rubbing. Is that correct? Then if I add aftermarket shocks that are longer than stock, I could actually get more articulation (up to the limit of my springs) without a lift? What about the pinch seam? That is already trimmed at the factory but would I need to do more cutting than what has already been done?
If we go this route we'll drive it with the 3.73s for a bit and see how it goes, but if we feel it's a bit under powered I would like to know what I'm looking at for new gears. The gearing charts show that at 70 mph, 4.88s are the beginning of the "performance" ratios for our Jeep. However, there's a lot of suggestions online toward 5.13s. This Jeep sees daily highway travel of 60-65 mph and frequent Interstate travel at 80 mph (not necessarily weekly but...). 4.88s are probably the right choice even if in a few years we go to 37" tires, correct?
Oh...and for the record...we're hoping to do more off-roading but we'll probably only be able to go a half dozen times year at most. I hate to admit that but I gotta be honest.
Now I'm considering a different route. Rather than big tires and a lift, I'm considering big tires, flat fenders, and maybe a re-gear. I'm looking for some clarification to make sure that I understand what I've read. We are talking about a 2014 JKU Rubicon X Package with a stock suspension, 3.6 Pentastar, automatic transmission, and 3.73 gearing. I have new 17" wheels on order with a 4.5" backspace and I'm looking at running BFGoodrich KM2s in 35x12.5x17 (closer to 34" real world would be my guess).
...
With flat flares and minimal trimming of the rear fender well pinch seam, 35" tires can be run on 4.5" or less backspaced wheels with stock front bumpstops and about 2" rear extended bumpstops. So, you could run shocks that measure up to about 15" collapsed in the front and about 17.5" collapsed in the rear without bottoming them out. To gain more than stock articulation (flex), you'd run as long a shock as your springs would permit, as long as the collapsed length of the shock was at or less than the 15"/17.5".
...
With flat flares and minimal trimming of the rear fender well pinch seam, 35" tires can be run on 4.5" or less backspaced wheels with stock front bumpstops and about 2" rear extended bumpstops. So, you could run shocks that measure up to about 15" collapsed in the front and about 17.5" collapsed in the rear without bottoming them out. To gain more than stock articulation (flex), you'd run as long a shock as your springs would permit, as long as the collapsed length of the shock was at or less than the 15"/17.5".
...
Did I read planman's information I quoted above correctly?
With the wheels I have on order (4.5" bs), flat fenders, stock suspension including the stock shocks, and 2" rear bump stops I'm good to go with 35" tires? Basically I would have factory off-road performance but with bigger tires and no rubbing. Is that correct? Then if I add aftermarket shocks that are longer than stock, I could actually get more articulation (up to the limit of my springs) without a lift? What about the pinch seam? That is already trimmed at the factory but would I need to do more cutting than what has already been done?
If we go this route we'll drive it with the 3.73s for a bit and see how it goes, but if we feel it's a bit under powered I would like to know what I'm looking at for new gears. The gearing charts show that at 70 mph, 4.88s are the beginning of the "performance" ratios for our Jeep. However, there's a lot of suggestions online toward 5.13s. This Jeep sees daily highway travel of 60-65 mph and frequent Interstate travel at 80 mph (not necessarily weekly but...). 4.88s are probably the right choice even if in a few years we go to 37" tires, correct?
Oh...and for the record...we're hoping to do more off-roading but we'll probably only be able to go a half dozen times year at most. I hate to admit that but I gotta be honest.
Forum Tech Advisor
Joined: Jan 2008
Posts: 1,208
Likes: 11
From: Billings, MT
Yes. You could do 35s with 2" rear extended bumpstops with a limited amount of rear pinch seam trimming and factory springs. You would have 2" less up travel in the rear.
Usually, people would do this with a 2"-2.5" lift so that the amount of uptravel in the rear suspension before the bumpstops are compressed is the same as stock.
I haven't drooped out factory springs. So, I don't know how much longer than stock shocks you could run without unseating the coils.
With what you have described, 4.88s would be the better choice over 5.13s because you have a '12+ transmission.
Usually, people would do this with a 2"-2.5" lift so that the amount of uptravel in the rear suspension before the bumpstops are compressed is the same as stock.
I haven't drooped out factory springs. So, I don't know how much longer than stock shocks you could run without unseating the coils.
With what you have described, 4.88s would be the better choice over 5.13s because you have a '12+ transmission.
Thread Starter
JK Newbie
Joined: Feb 2014
Posts: 22
Likes: 0
From: Missouri
Thanks for the information. Ultimately we want a 2.5" lift and I'm seriously looking at the Metal Cloak Game Changer ARB edition. The idea is to run the stock suspension and gears to see what we think of the 3.73 gears with the 35" tires for a bit. If we can live with that then go for the lift next. If we don't like the gearing, go for the new gears and leave it stock height.
It's just a budget thing.
It's just a budget thing.
JK Freak
Joined: Oct 2012
Posts: 631
Likes: 0
From: Pittsburgh, PA
I agree with the budget boost. I was gonna recommend that cause they're very inexpensive and will get you lifted a bit so you can focus your funds elsewhere with your build.
Sent from my Galaxy Note 3 while crawling over mini trucks.
Sent from my Galaxy Note 3 while crawling over mini trucks.
Trending Topics
JK Newbie
Joined: Mar 2013
Posts: 96
Likes: 0
From: California
you are doing basically what i did. 2013 auto, 4 door, 3.73 gears - my initial goal was to do the absolute minimum required to get 35s on without horrible rubbing - so i put on a BB (i just went super cheap with the daystar 1 3/4 coil spacers). 35's on 4.5 BS steel wheels, flat fenders, a little trimming, quick discos and everything else suspension wise is stock. my BB didn't even have shock extenders so i effectively moved 2" of my down travel to up travel which isn't ideal but is ok for now. i didn't change bumpstops and am rub free except when i'm disco'd off road and then i get a little rubbing but nothing problematic. i haven't checked as i don't really want to know but i expect my shocks are the limit in my up travel, down travel or both - but the sooner i trash those the sooner i can upgrade! i was gonna add shock extenders or new shocks but then the scope started to creep on me and now i'm looking at the metal cloak game changer lite/arb edition.....