gears gears gears

[BenLandry]

Maybe it’s the weight of the beadlock wheels that make the difference? I have no idea, just a guess. It looks like your wheels are probably reasonably light or at least not excessively heavy. Nice build btw!

All that said this thread is informative and potentially valuable for me since my 392 just arrived and I want to put on 37’s with KMC beadlocks on it and have been mulling over 4.56 or 4.88 gears.

The rims are 20x10. The tires are Nitto Trail Grapplers. The weight of my spare made my tail gate sag with the Mopar reinforcement kit, I had to upgrade to the Teraflex Hinge reinforcement kit. They are pretty heavy. I know beadlocks are heavy. Just trying to put real world stuff out there. I’ve had my 392 longer than most but I am no expert and my Jeep is a street racing mall-mud crawler.

 

[Bhplumber]

Okay, there are literally 100's of 'what gears should I run' and 'when should I regear' posts on this forum. Please check them out because y'all might learn from them and be able to quickly determine the answer that works for you and your specific build. But, in the interest of fun, I'll open class on Gears 101 for all you mall.crawlers out there.

First, the internet is full of experts and they all have opinions... But most of jeep forum experts run spacer-lifts, wear skinny jeans, off-road with a rooftop tent, and carry decorative traction boards . If this is you, or you drive a Taco, this is for you! If you don't know what a Taco is,... this is also for you. If your forum profile also includes your preferred pronouns... I think you found this forum by mistake and Taco = Tacoma



Step 1:. Ask yourself a few simple questions if you are considering a re-gear --- Have you lost a little pep and can't hold 8th gear? Do you think the gearing is too agressive for the type of off-roading you do? Do you have a dedicated crawler that you trailer to the trail and on-road use is not a concern? Maybe you keep breaking gears and you want to move down from 5.38 to a 4:88?

Step2: What are your expectations and how much is it worth to you to regain lost performance? For example, performance loss (392, not a Prius) that you will experience by running a full set of 37" tires, on headlocks, is comparable to throwing a few fat kids in the back seat and going for a drive. Expect to pay $1,500 to $3,500 to re-gear your Jeep.

Step 3: sanity check... Are a few fat kids enough to necessitate a re-gear on a jl 392? Your call! I went from a stock weight, roughly ~5,103 lbs, added a.bunch of mods, and now weigh in at 6,300+... I regeared from 3.73 and went to 4.56 and I did that after all the other mods. 8th gear is back and I find the shift points, in 4-low, to be more comfy. Some pics below. Please notice that spacers were not used to lift this vehicle, rooftop tent fell off on a jeep trip (thankfully, we almost rolled) and my traction boards did not survive their first use.

Lastly, for the internet experts out there... Here is a fun bonus for you- Torque, transmission, and transfer case make the jl 392 a whole other animal compared to any hemi -swapped jk or a tj and it is idiotic to.draw any comparisons. Apples and oranges. Heck, the 3.6JK.and a 3.6 JL aren't even a close comparison.... And I've personally tested this .

Just a little food for thought. I bought and own a 21 392 XR which came with stock wheels and tires, factory steel winch bumper, winch, and KC light bar. The performance was great, just to remind you this is "STOCK 315 BFG's with 4:56", BFG's are maybe 34" tall on a good day brand new. Now I added 37x12.50x17 Trail Grapplers on 17x9 beadlocks, upgraded to a real winch bumper, lost the light bar and guess what, I lost a lot of zip. I essentially went backwards from what you did. So to get back to what my XR stock ratio was with the now 37's my options are to go 4:88 which would get me within 50 +/- lower RPM of the factory set up, 5:13 would be about 100+/- higher RPM, or go to a 38" tire with 5:13 and get within 25+/- RPM of stock. So I guess what I'm saying is if you want stock XR performance with 37's 4:56 will not get you there and trust me it's a very noticeable difference when you lay into the throttle. I'm sure going from 3:73 to 4:56 was a huge improvement but you do not have stock XR performance with 37's and 4:56's. Yes all of this depends on actual tire height.

I am actually leaning against "the norm" and really thinking I'll go to 38's and 5:13's. Now that will open another whole can of worms for everyone. Yes the pinion is weaker, yes I should probably upgrade to Dana 60's or 70's to go that low if I going to wheel it. This Jeep most likely will never be in a situation where I'll bind up the drivetrain and hammer down on the throttle. I have a crawler and a SXS to thrash on the rocks and crazy stuff with. Will it get "wheeled" yes just not to the point of possible carnage but I will have my "stock XR" feel when I hit the gas.

Oh and just one more point or opinion I'd like to throw out there. If you own a 392 with 37's or really a 392 at all and are worried about you MPG you need shop in the 2.0 Sahara section at the Jeep dealer next time

 

[prodriquez]

Just a little food for thought. I bought and own a 21 392 XR which came with stock wheels and tires, factory steel winch bumper, winch, and KC light bar. The performance was great, just to remind you this is "STOCK 315 BFG's with 4:56", BFG's are maybe 34" tall on a good day brand new. Now I added 37x12.50x17 Trail Grapplers on 17x9 beadlocks, upgraded to a real winch bumper, lost the light bar and guess what, I lost a lot of zip. I essentially went backwards from what you did. So to get back to what my XR stock ratio was with the now 37's my options are to go 4:88 which would get me within 50 +/- lower RPM of the factory set up, 5:13 would be about 100+/- higher RPM, or go to a 38" tire with 5:13 and get within 25+/- RPM of stock. So I guess what I'm saying is if you want stock XR performance with 37's 4:56 will not get you there and trust me it's a very noticeable difference when you lay into the throttle. I'm sure going from 3:73 to 4:56 was a huge improvement but you do not have stock XR performance with 37's and 4:56's. Yes all of this depends on actual tire height.

I am actually leaning against "the norm" and really thinking I'll go to 38's and 5:13's. Now that will open another whole can of worms for everyone. Yes the pinion is weaker, yes I should probably upgrade to Dana 60's or 70's to go that low if I going to wheel it. This Jeep most likely will never be in a situation where I'll bind up the drivetrain and hammer down on the throttle. I have a crawler and a SXS to thrash on the rocks and crazy stuff with. Will it get "wheeled" yes just not to the point of possible carnage but I will have my "stock XR" feel when I hit the gas.

Oh and just one more point or opinion I'd like to throw out there. If you own a 392 with 37's or really a 392 at all and are worried about you MPG you need shop in the 2.0 Sahara section at the Jeep dealer next time

OMG, my old post and back when I was still on stock axles, 37’s and 4.56 gears!!!

You should totally do it if you’re not going to wheel it and you don’t mind the higher rpm’s.

But I also want my wife to put a Whipple supercharger in her 392 and we only drive her Jeep to the grocery store and back.

Jeepers can go crazy on upgrades… but very few are really necessary as long as AAA is a phone call away and the gas station is down the street

Cheers