37s on non-Rubicon, any issues?

twisty

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I think the guys with rubi's (me) 44's and 37's are fine IF you put in stout shafts. I put in RCV's (so did the guy in the video after his splines bent) and yukons in the rear. I poured over the interwebs prior to dumping the money into them and they are holding up quite well. Bigger then 37s is where the trouble starts IF your hammering.

The non-rubi's with 3.45's and 30s ?? up front, yeah 37s arent the thing.

Good to know the ball joints now have upgrades. I might be proactive and get them done.
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DadJokes

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For what it's worth the people who actually built those axles, Dana/Spycer, have said 35s for mall crawling and LIGHT off road use. Anything in terms of harder wheeling or larger tires is not recommended on the Sport and Sahara axles.
The garage you talked to and the people at the beginning of this thread are right, stick with 35s and a 2.5" lift and you will avoid a lot of headaches.
Bumping to 37s is going to bite you eventually. Plus you have 3.45 gears in your Jeep and 37s want 4.88 or 5.13 gears which means you will never see 8th gear in an auto or 6th gear in a manaual. Even running 35s without re-gearing you will barely touch those high gears.
Thanks for relaying that! I’m awfully tempted to go for 285/75/18’s on my stock wheels but I do want to be able to hit moderate trails. I’m thinking now maybe I should stop at 275/70/18’s (33.2-33.5) or at most the expensive 285/70/18 (33.7”) size.

Is there reference material where I can read up on where they made that recommendation?
 

DadJokes

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I think the guys with rubi's (me) 44's and 37's are fine IF you put in stout shafts. I put in RCV's (so did the guy in the video after his splines bent) and yukons in the rear. I poured over the interwebs prior to dumping the money into them and they are holding up quite well. Bigger then 37s is where the trouble starts IF your hammering.

The non-rubi's with 3.45's and 30s ?? up front, yeah 37s arent the thing.

Good to know the ball joints now have upgrades. I might be proactive and get them done.
When he said the wobble went away when he replaced the bail joints I made a mental note...just in case. I’m glad they released a revised and more HD part. Reminds me of Dodge Dakota’s 20 years ago, weak ball joints.
 

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Thanks for relaying that! I’m awfully tempted to go for 285/75/18’s on my stock wheels but I do want to be able to hit moderate trails. I’m thinking now maybe I should stop at 275/70/18’s (33.2-33.5) or at most the expensive 285/70/18 (33.7”) size.

Is there reference material where I can read up on where they made that recommendation?
No problem :)
About a year ago there was another guy on the forum in the same boat about wanting to go up in tire size on his Jeep. I forget what model but he had the D30/35 combo. He called Dana and that is where that info came from, I'm sure it's still on the forum somewhere and if you've got time to kill you can probably find it.
In the end we wound up swapping out to D44 axles and avoided the whole mess of beefing up D30/35s.
 

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Game Changer on a Sahara. If you're going to wheel that hard you should have bought a Rubicon. I think the Game Changer is probably overkill on your Jeep plus you can save a lot of money.
 

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I think there is a lot of wisdom in the comments so far. I have the 4cly Rubi and went from the stock 33" to 35" and then to 37" tires. As noted by others above, tire size is a major cost driver for other components on the rig (steering, gears, axles, etc.). I have stayed with the stock Rubi gearing (4.10) so far and the performance is fine - still fast off the line, up steep freeway grades and passing a highway speeds. However, there was a much more noticeable performance impact going from 35 to 37 than from 33 to 35. I rarely saw 8th gear before and now it is even more rare but 7th is there all the time. Fuel mileage is also down in the mid teens from the low 20s with the stock car on 33s. I suspect with the 3.73 gearing, the speed off the line and up hills or passing may suffer significantly and you may be down to functionally a 6-speed transmission (apologies if you don't have the 8-speed auto). Note that I have about 800lb extra for bumpers, suspension and steering gear so the impact is greater than just changing tire size.

Folks above also mentioned the tire carrier which can be accommodated with a MOPAR tail gate reinforcement and a tire carrier mod - so far, I am not seeing any issues with the 37". I went with the Teraflex tail gate mounted tire carrier and have liked it (among other things, look at the complexity to reposition the brake light and rear camera when you do this - Teraflex is easy). A bumper mounted tire carrier has some benefits but can add a lot of weight and may require a new heavier bumper depending on what you have now.

Lastly, don't forget coming up with a plan on how to replace a tire should you need to. A 37" and wheel is going to weigh around 100lb so unless you're a pro weight lifter you will need to figure out how to get it off and on your tire carrier, jack the rig up high enough to take a wheel off the ground and get it on and off of the hub. There are some other threads here that address this.

What drove me to 37" is that there is no question they are better off road so I was willing to take the hit for them once I realized that the driving performance would still be acceptable w/o re gearing and I am happy with the outcome.
 

steverj64

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After scrolling through the forums I referred back to GeepNee's original post. Build it how you want and replace broken stuff as needed. First call or research Metalcloak (and other brands of interest to you) and determine which of their lifts will work best with 37"s on your Sahara. The Rubicon out of the box is 2" taller (and has the heavier axles) than Sports and Sahara's so 2.5" may not be quite enough. Amongst other things I would do (initially) is spare tire carrier/hinge upgrade, and a recalibrator tool to keep the speedo and shift points happy. Then keep throwing money at it until you got it how YOU want it. Steps, gears (4.88?) etc. Also talk to your dealer about your warranty. HAVE FUN
 

RidgeRider

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This is a second SteverJ64 on getting a Tazer JL Mini or similar device to set the tire diameter in your system or your drive train will be confused as to what happened and it won't drive right plus your speedo will be way off. You can have someone (like the dealer) do this for you permanently but the problem is that it is not an exact measurement from the tire how to do this. People have different philosophies but mine is to match the GPS and speedometer speed. For my 35" tires this happened at 34.6" and for my 37" tires it is at 36.5". I've had others say that the way to do this is measure your OEM tire distance from the ground to the hub center (with proper inflation) and then your new tire and adjust accordingly. This will give you a generally lower diameter measurement and may work but definitely will not align your speedometer speed with GPS speed. Others just program in the manufacturers stated diameter but that is usually not the diameter that the loaded vehicle sees at the pressure you want with the wheel spinning. With a Tazer you can keep fiddling until you get it right for you.

Additionally, if you look in these forums, there is a whole lot of comments about the tire pressure in your new 37" tires. Most will say that a chalk test will have you in the mid to low 20s (psi) but most suggest plus/minus 30 psi as a more practical place to be (I run just over 30). If you trip through your factory TPMS setting at your preferred pressure or if you want to air down for off road, the Tazer will let you adjust the TPMS setting or turn it off all together.

There are also many other things your Tazer or other tuner can do. An advantage with the JL Mini is that the dealer can still access the system w/o disconnecting it (at least my dealer has been able to do it). I understand that some tuners cover the diagnostic connector which means you have to remove it to take it in for service.
 
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GeepNee

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I appreciate all the feedback and input. And after some consideration, I am going the conservative way, with a 2.5" lift and some 35s. I'll post pictures when its done. Wheels and tires are in hand... now just waiting to get the lift.

I'm leaning towards the AEV 2.5" kit as i heard the ride is smoother than most.
 

Reabob

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35" with 2" lift kit.
If 37, change diff and brakes and go with 3" lift.
 

InfamousYert

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Game Changer on a Sahara. If you're going to wheel that hard you should have bought a Rubicon. I think the Game Changer is probably overkill on your Jeep plus you can save a lot of money.
If you're going to wheel that hard you should have bought a sport and axle swapped with Dana/Spicer axles.
 

jmcdtucson

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After scrolling through the forums I referred back to GeepNee's original post. Build it how you want and replace broken stuff as needed. First call or research Metalcloak (and other brands of interest to you) and determine which of their lifts will work best with 37"s on your Sahara. The Rubicon out of the box is 2" taller (and has the heavier axles) than Sports and Sahara's so 2.5" may not be quite enough. Amongst other things I would do (initially) is spare tire carrier/hinge upgrade, and a recalibrator tool to keep the speedo and shift points happy. Then keep throwing money at it until you got it how YOU want it. Steps, gears (4.88?) etc. Also talk to your dealer about your warranty. HAVE FUN
As far as the suspension goes, Sahara is only .75" shorter than Rubicon. Sport about 1.5". Tires add another .5".
Quoted lift height is going to be in reference to a Rubicon. So add .75" to get likely results for Sahara.
 
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