37s questions
 

So I was about to buy my 35s when I found a deal and a 37 is only $15 more a tire. What would I need to run these on a 2.5 lift? Would I need a larger lift? Also as far as power goes, I have a 3.6 with the 6speed in my 2 door and 3.73 gears? What would I need to re gear to or is it necessary? Also how would this effect power, mileage etc? Really thinking the 37 would be the way to go if I can figure it all out, thanks!

Also I have the smittybilt flares on

Do the 37's because eventually you will anyway. With the 6 speed you maybe able to tolerate the 37's for a while but may want to consider 5.13's down the line. 2.5" with 37's will likely require some trimming if have not done any. Your power and mileage will be affected negatively. But how negatively will be contingent on your right foot.

I have a friend that runs 37s with a 3.6 six speed and 3.73s. He was daily driving it till he got his new work truck. Said it wasn't bad, he just pretended like it was a 5speed. He has 3.5in lift and flat finders and rock crawls the crap out of it.

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People will tell you what you want to here. Truth? I ran 3.73s on that setup and it sucked. 37s would really suck. Not to mention the stress it would put on your drivetrain. Your clutch will especially feel the love. You obviously don't have a rubicon, so anything offroad other than trails will be terrible.

Do it right or don't do it. Also, that front axle of yours is not designed to run a tire that large. Following that comment will be people saying they did and it works. Ironically, one of the biggest advocates of D30 and 37s on another forum just blew up his front ring and pinion this week while idling over a rock. You'll need to truss the housing if you don't want a bent axle. Although, you should do that with 35s too.

That's not the way to do 37"s. If you think you want to do 37"s then hold off for a bit and plan your build out. Half ass and 37+ tires do not go together.

I agree, I have 37's on a 4" lift but I have a Rubicon and it handles great rock climbing and I drive it as a daily driver and get 15 mpg. but in your case I would stay with the 35's until you can at least upgrade your gears or you are asking for gear and clutch problems. My best friend just snapped his rear axel with 37's and 3" lift due to having a base 4 door and it was an automatic, and the terrain wasn't that extreme. Wear and tear will get your weakest link.

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I had 2.5"lift 37s,3.6,6 speed,smittybilt flares, I had 3.73 now I have 5.13. It's not the end of the world if you don't regear right away. Just sleeve and gusset your Dana 30 and heavy duty ball joints.

Be prepared to trim the rear pinch seams right to the tub and put on some flat fenders on. 2.5" is likely gonna rub. When flexed.

3.73's, 6 speed, and the 3.8l here. It was doable but only for looks. I had an extra set of tires and wanted to see what it was like. Aside from the major power loss, I could feel the steering pump screaming to take off the 37*13.5's. It's not something you want to live with.

Your better route on this would be to buy some used 37's that are at the end of their life and try it out. Get everything together for them. Realize you hate the downfalls and go to a 35 with everything strengthened up already. You also need to consider brakes, steering, and clutch life with larger tires. The brakes don't grab as well, the steering pump will want to kill you in your sleep, and the clutch needs more throttle to get rolling. Downshifting will be incessant unless you'd just like everyone to zoom past you on the interstate.

I've now got the 37*13.5's on a 2015 Rubi (4.10/ 6 speed) and while it is a little better, it's not better enough to where I would want it everyday.

I think I may stick to the 35s. Even with the 35s I planned on beefing up the Dana 30 in the front for sure. I was going to get the truss and gussets for it. Should I go ahead and sleeve it too? I know it can handle the wheeling I do now but I keep getting into rougher stuff and I know with 35s I'm going to keep pushing it so I'm thinking that for the $500 or so to beef it up it should hold up for what I get in to. I don't do any major rock climbing out here. And as long as it holds up strong (knock on wood) when the day comes that I want to buy built 44s and run 37s, I should be able to get a decent resale on the built up 30.

Does anyone have any experience with lockers in the 30 and/or any build list that they may have done to theirs.

Also if anyone has in misc axle junk or setups laying around I may be on the market ;)

Thanks for the help guys!

Screw 37's and get 42's you will want them anyway. I am sure you can find someone to tell you how driving around on 42's and 3.21 gears is just fine. Just don't use more then 4th gear and only go in a straight line. Don't worry about the clutch, ball joints, and driveshafts because they are just wear items anyway.

Regear
Ideally beefier front axle housing and C's and get it with the new gears and axle shafts installed
stronger axle shafts front and back
trim pinch seam

My situation is a little different than yours but here's my experience with 37's, but first specs: 2door,3.8,auto,5.13 gears RK 2.5" (really more like 3.5) it sucks! I love the way it looks and the way it works Offroad, but I am constantly worried about breaking something and looking for a way off an obstacle if I were to break it, I have an artec armor kit for it but haven't got around to install it yet, I have also wheeled it pretty hard (nowhere near invest2m4 hard though) and not had any issues, hell I wheel with a guy that has broken multiple rcv shafts on a 4cyl tj so I'm not easy on it but it still scares the shit out of me and keeps me from making some of the obstacles I should be able to do. And with that said I am probably going to grenade my d30 this weekend on the super easy trails we are going to

I think you got the right idea. I personally wouldn't mess with a front locker if you think you will upgrade your axle at some point. Throw one in the back and call it good if you think you need it. Gussets are easy - sleeves or truss is a bit of work. If you truss it - i wouldn't sleeve it.

Ok I gotta know more info on the poor sob :D

I don't think anyone is really trying to tell someone what they want to hear. I think what they are saying is yes it may work for. While but don't be surprised if you experience some damage alone the way and be prepared for some gears or whatever. I am not hardcore as some but I am not into the competition cuts and bodies that looked like chewed up bubble gum. I like to have a good time and drive it home. I had a TJ for 13 years D35 (Super35) and a D30 with 4.88's and 37's for 10 of the 13 years and had a blast. Never an issue with the 30. I did go thru a couple ring gears in the 35 but it's to be expected down the line. For $15 more a tire for something I would get in the long run anyway I would just do it and replace shit as I needed. Most of us began the Jeep addiction with a cheap lift and tires too big to allow the transmission to be most effective. I would not waste a dime on a D30 sleeving and gussets. A D30 anyway you look at it really ain't worth a bucket of piss in the first place. I recall back in the day when you had to have a D44 and then it was an 8.8 and then a D60 (RJ's were the shit and now I hear people say those suck) and then a 14 bolt and now D70's or 80's. WTF! Put whatever tires you want on there and drive it until it breaks, if it breaks and then upgrade. Just drive it like you want to make it home. Don't be a pussy while wheeling, have fun but don't be surprised if along the way you get some damage that requires remedie$. Do the tires and get some gears. I assume Marine in NC you are at Lejeune? There is a guy in Conway SC that does ring and pinion swaps pretty cheap. Or maybe someone just as cheap closer. There is a guy on here with a Hemi D44's, 5.13's and Toyo 38's that runs the piss out of his. Sorry I am raggin' today and no disrespect to anyone. All the aftermarket manufacturers I would imagine respond more to demand (of structurally stronger and better hit) than that of requirement.

Lol I like you! Wheel it till it breaks! Dana 35 and 37s bolt move but looks like you proved some people it's possible! Personally if you know how to wheel you should just be crawling over everything not just being light on the peddle but knowing when and how much power is needed!

Personally I would keep stock axles shafts in the d30. Easier to swap a shaft then r&p.

I got new tires today and as bad as I wanted the 37's I went with 35's. In a M/T the weight of the tire is already astronomical and I have heard of some mild balancing issues when you start to get into this size range. Combine that with the D30 front axle and this is my daily I just couldn't get my head around dealing with the 37's. They would have looked amazing but just not practical for my usage.

You're pretty much in the same boat I'm in with the Sahara. I'm running 35's would like to go 37 but I don't see that happening until at least the front axle gets changed out.

In the meantime, gusset your C's, slap in some Teraflex HD ball joints, and put in some Nitro sleeves (or you can go the weld-in sleeve route which btw I happen to have a set of the Teraflex versions laying around if you're interested). Throw an ARB cover or Rancho diff skid on it and you'll be fine especially since you're not doing any rock crawling. Beef up your tie-rod and trackbar at the very least if you haven't done so already.

I wouldn't bother with a front locker for the D30. Most people I know hardly ever engage the front locker unless they're wheeling in heavy snow.

Having said that, I have thought about throwing in an LSD for the front. I just have to really ask myself how realistic it will be that I change the front axle out in a couple of years. Plus I still need to regear as I'm currently on 3.73's which I'm really starting to hate with the 35's so it's probably smarter to do the regear, locker/LSD, with a stronger front axle all at the same time.

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After 7 years I finally swapped out the D30 for a D44J8 .. For me it was cheaper then rebuilding the D30 with gears and locker, etc.

The new D44J8 housing cost about the same as it would cost me to have the D30 housing trussed and gusseted. All the other new parts were on par for both diffs.

Negative.

haha... yep, 5.13 would be for the 3.8L engine, 2007-2011 JKs.... 2012+ w/ the 3.6L, 4.88 is ideal.

I actually just put on 37s and can't regear for a few weeks (manual, 3.6L, w/4.10) and I have to say I was surprised that it wasn't worse than it was. It is much more driveable than I thought it would be and now I at least understand why people think it is fine. Still feels like the gearing is too high and can't wait until my regear appointment gets here.

gearing chart down by one of out members for the 3.6L engine.
Attachment 638216

I have moving around with 3.6 and 6 speed and 37" with stock 4.10 gears with no issues. I am also on no lift and Metalcloak Fenders and bumper. Clears just fine and runs okay, not a sports car.

The biggest thing I notice is the brakes... the 37" Coopers and Atx Slabs and jeep with all Metal fenders, heavier bumpers front/winch and rear and spare. Thing just seems to struggle to stop quickly.

I added the Powerstop brakes to my 37" setup. Sleeved and gusseted w/ HD ball joints. Plan on a truss but also considering new axles at the same time.

You'll definitely need to trim your fenders or go flat. Regear w/ your year engine I'd go w/ 4.88's (had 3.21 and did 4.88). After that make sure you tune it properly otherwise it's going to feel like a dog still.

Exactly my plan.

I order Synergy Ball Joints today and King Bumps yesterday, looking at the Reid Knuckles next. I plan to the have c's done and a gusset added to the front by Motobilt in Dothan once I get the coilover suspension installed. Then RCV front shafts are on the list.

I have the Metalcloak Metal flat fenders front and rear installed currently and clears for road driving with no lift and 37"'s.

4.88's will be eventually, but to be honest, not on the top of my list of stuff as I am not completely struggling with the 4.10 gears. Then the labor cost to have them done, omg... wish I knew how to setup gears.

I will definitely have to address the brakes... they suck.

Looking at the Mopar Performance Brake Kit, with rotors, heavier calipers and booster.

Setting up gears is nowhere near as hard as people make it to be. Just as you're currently experiencing stock gears and 37s that many people say is absolutely terrible yet think it's "fine" is comparable to how people speak of the magic needed to set up gears.

I'am sure it is not once you have done a few and know what you are doing. I have plenty of time to do my, as the jeep is not my daily driver and can be down aslong as it would be needed to be setup correctly.

It is hard to swallow $1600 give or take cost to setup gears and parts (gears, bearings, shims, etc...).

Just not sure on how to do to be honest, never done gears in any vehicle I have had. I always find a shop to do it for me as I think it is some kinda black magic involved.. lol... kidding.

But just unsure on what to look for and tools needed, so I have always left it up to a professional.

Welding is another art that I have never tried learn and would definitely save me some money and allow me to fab up stuff on my own without help.

Luckily I've got a good friend who does gears back home so this summer I'll be going to 4.88s and it'll cost me like $600 and some crown royal.

So all in all after gears, truss, gussets, and diff covers I'll be in about $1200 for both front and rear. Not too shabby for a lot more protection.