I'm running OME light duty springs and wound up with just over 2.5" of lift and have the Currie steering. No issues at all.
Let's talk optimal build for 31" tires
- Thread starter Irun
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Damn, I gotta pay more attention to your Jeep next time I see you. Or, write down questions to help remind me
Paying attention to this thread though, while you Big Brain people hash out the details. Maybe I can run the trails these guys out here are doing with 35's.
Could you post spring numbers?
With stock front, on 932x front i didn't even get to 2", with 1 1/4 spacer i am still 1/4 shy of 3".
942x in the rear pushed it up a bit shy of 3"
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2932 and 2941 with a spacer up front to level the rake, plus OEM bumpers front and rear, no winch and my spare is a 31.
Happy to go thru all the details next time we're out or check the about section on my profile; they're all listed there. I am by no means an expert but I agree with many here that a well built, nimble Jeep with a capable driver can do a lot more that many think.Damn, I gotta pay more attention to your Jeep next time I see you. Or, write down questions to help remind me
Paying attention to this thread though, while you Big Brain people hash out the details. Maybe I can run the trails these guys out here are doing with 35's.
We are all definitely cool, but some of us are cool-ER!We drive TJs and LJs, doesn't that make us cool already? Maybe with the MCE flares we'd be exquisitely cool!
I agree you can do a lot on 31's. I did it on 31's for awhile. What I got tired of was hitting lower control arms, banging the TCase skid, pummeling the Gas Tank Skid, and smacking the rear bumper at times.
So let's say for 31's you go front and rear replacement bumpers (I'm looking at a JCR Offroad mid width with a winch and a poison spyder rear, with a morryde tire carrier) and a 31" spare. Which springs would be the best option? 2933 and 2941, with a 3/4" spacer to level it? I'm gonna spreadsheet this out for my build and I'll post it on here with links for anybody looking to do the same thing.
Those are the springs I have on my TJ, as well as 10mm spacer up front to level and I also run a 31' spare, but no Morryde carrier (yet). I wound up with closer to 2.75" of lift....but I have OEM bumpers front and rear and no winch. I don't know what those bumpers weigh, but the OEM weigh next to nothing, so with a winch up front and depending on how heavy those bumpers are, you may want to consider the heavy duty springs.
Edit:
I was wrong on the springs; I actually have the 2932 and 2941 springs and a 10mm spacer up front.
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There's no definitive answer for this question. Results seem to vary. It's all related to your sprung weight (how much weight front and rear coils are holding up relative to weight distribution) and consistency of coil spring ft/lb manufacturing (a safe assumption for sake of discussion). Spacers seem to be in everyone's solution with OME springs.
For example, I have 2933 and 2942, 3" front and 3.25" rear with a 60lb winch and 39lb front bumper (- the OEM bumper), with MCE flares (-9lbs up front), an AntiRock, which seems lighter than the stock swaybar. No spare, no tire carrier at all. Hardtop on. Rear seat in. Rear Warn bumper (don't know weight). Tank fluctuates, of course.
But to get the 3" and 3.25", I use a 1.5" spacer up front and a 10mm (0.39") spacer in rear.
@JMT is right, just too many variables to know for sure. I run the same springs as him, with 1" spacers front and rear for 3" of lift, minimalist front bumper, winch, mid with rear bumper, stock tire carrier with skinny 33 spare, no back seat, hard top. I have about 1/4" rake, but 10+ year old front springs and fresher rear springs, so the fronts have sagged just a tad.
So to pick the proper spring is it an educated guess, or would I need to get the bumpers on first and bring it to a weigh station?
When buying springs, it is an educated guess, unless you know the Jeep's sprung weights. If you are buying linear rate springs like Old Man Emu, the final ride height can be closely calculated. If you currently have a set of linear rate springs, and you know their rate and free lengths, then you can closely calculate the Jeep's sprung weight. Then you can make a highly educated about the next set of linear rate springs you want to buy.
If you look back at the first 5-6 years of my build and all I told you was that I had steel bumpers, you would wonder why I wasn't getting as much lift out of those springs as most usually do. I still have steel bumpers, but the Jeep is now 300lbs lighter in those areas than it used to be.
As a thought exercise for everyone, let's add that 300lb weight to the center of a Jeep with 140lb/in springs on all four corners. How much does the ride height change?
Decide where you want to be, get user feedback. Yes, it’s an educated decision to start, but open ended as far as what you might need to change. Don’t worry, bc with your OCD, you’ll get it right the first time.
Ok, I was talking to @Irun today, and it got me to looking close at my OME 2933. If I measure from the lowest part of the spring, at the retainer, to the top of the spring, I’m getting exactly 2” out of the spring. Plus the 1.5” spacer. I’m at 3.5” of lift front, 2” bumpstop, axle forward enough so no rubbing at full bump. I apologize for any misinformation.
Ooh, ooh, I know!
F = -k*x, where F is force, k is the spring constant, and x is spring displacement.
300 lb at the center of mass, evenly loaded on each corner: 300 lb / 4 = 75 lb
F = 75 lb
k = 140 lb/in
Rearranging to solve for x, we have x = F / -k
so x = 75 lb / -140 lb/in
and the grand answer, a loss of 0.54 inches in ride height!
As a side note, The more parts I add to the Jeep, the more I realize the importance of saving weight. It really hit me when I replaced my steel full width bumper with a stubby aluminum (12 lbs!) then added a winch. Then, I replaced the steel line with synthetic. What a difference! It certainly pays to be weight conscious with upgrades, in more areas than getting the right amount of lift out of your springs.
Edit: @jjvw how did you lose 300 lbs in those areas while sticking to steel bumpers?
F = -k*x, where F is force, k is the spring constant, and x is spring displacement.
300 lb at the center of mass, evenly loaded on each corner: 300 lb / 4 = 75 lb
F = 75 lb
k = 140 lb/in
Rearranging to solve for x, we have x = F / -k
so x = 75 lb / -140 lb/in
and the grand answer, a loss of 0.54 inches in ride height!
As a side note, The more parts I add to the Jeep, the more I realize the importance of saving weight. It really hit me when I replaced my steel full width bumper with a stubby aluminum (12 lbs!) then added a winch. Then, I replaced the steel line with synthetic. What a difference! It certainly pays to be weight conscious with upgrades, in more areas than getting the right amount of lift out of your springs.
Edit: @jjvw how did you lose 300 lbs in those areas while sticking to steel bumpers?
Start with really big bumpers and tire carrier and eventually switch to really small bumpers and put the tire back on the tub.
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