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Do I need to regear / buy a new front axel / or truss reinforce?

Izzo93

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This is for my wife’s 2018 JLU Sport Automatic 8speed...
So I bought a 3.5-4” lift for my wife’s JLU Sport..I just bought 17x9 Fuel Vapors & 37/12.50r17 BFG Ko2 A/Ts. My suspension lift should be in within two weeks, and my buddy and I are gonna slap that together, then I’m heading over to my local DiscountTire shop to have the new wheels and tires thrown on.. so here’s the nitty gritty.. until my warranty is up I’m going to be doing 0 rock crawling or trailing. (I’ll just be on my side by side till then or on pavement riding my street glide), so 100% pavement. I went with the Ko2s over Mickeys, Nittos, or Mid Grade Patagonia’s due to the fact they were the lightest “37 inch” tire I could find, and were smaller than any 37” tire out there but still bigger than 35s. And until my warranty is up in the next year and a half I wanted to get the best use out of my tires because it’s just going to be two and from work at speeds 44-55 mph with 12 minute trips two and from work or the occasional 75-85 mph trip on the highway to camp which is a two hour commute one way. I’m 100% new to the jeep community, and I’ve been researching and reading forum after forum. YES, I know my Jeep will feel sluggish. Even going from stock to 35s, especially the jump to 37’s that I made. But the way I am applying my JLU for the next year and a half / two years , am I going to make a terrible decision by not reinforcing, re gearing, or outright buying new axels? I would appreciate as much honest insight as possible. Thanks again guys. So yes. I am going to be the despised “Mall Crawler” for the time being

Also, before this gets asked, again me being completely new to jeeps, from what a buddy told me, is I bought the worst if not the 2nd worst kit I could’ve possibly bought which was the 3.5-4” skyjacker dual rate suspension lift with optional high clearance dual steering stabilizer. I’ve now made that purchase, along with the wheel and tires, and I’m not sure if I’ve already set my wife’s JLU up for failure, or if it kinda is what it is, but I would prefer to get the advice from you guys who have been doing this proper knowledge and sound advice rather than me just going on a whim
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Headbarcode

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This is for my wife’s 2018 JLU Sport Automatic 8speed...
So I bought a 3.5-4” lift for my wife’s JLU Sport..I just bought 17x9 Fuel Vapors & 37/12.50r17 BFG Ko2 A/Ts. My suspension lift should be in within two weeks, and my buddy and I are gonna slap that together, then I’m heading over to my local DiscountTire shop to have the new wheels and tires thrown on.. so here’s the nitty gritty.. until my warranty is up I’m going to be doing 0 rock crawling or trailing. (I’ll just be on my side by side till then or on pavement riding my street glide), so 100% pavement. I went with the Ko2s over Mickeys, Nittos, or Mid Grade Patagonia’s due to the fact they were the lightest “37 inch” tire I could find, and were smaller than any 37” tire out there but still bigger than 35s. And until my warranty is up in the next year and a half I wanted to get the best use out of my tires because it’s just going to be two and from work at speeds 44-55 mph with 12 minute trips two and from work or the occasional 75-85 mph trip on the highway to camp which is a two hour commute one way. I’m 100% new to the jeep community, and I’ve been researching and reading forum after forum. YES, I know my Jeep will feel sluggish. Even going from stock to 35s, especially the jump to 37’s that I made. But the way I am applying my JLU for the next year and a half / two years , am I going to make a terrible decision by not reinforcing, re gearing, or outright buying new axels? I would appreciate as much honest insight as possible. Thanks again guys. So yes. I am going to be the despised “Mall Crawler” for the time being

Also, before this gets asked, again me being completely new to jeeps, from what a buddy told me, is I bought the worst if not the 2nd worst kit I could’ve possibly bought which was the 3.5-4” skyjacker dual rate suspension lift with optional high clearance dual steering stabilizer. I’ve now made that purchase, along with the wheel and tires, and I’m not sure if I’ve already set my wife’s JLU up for failure, or if it kinda is what it is, but I would prefer to get the advice from you guys who have been doing this proper knowledge and sound advice rather than me just going on a whim
First off, I highly recommend getting the Tazer programmer from the company Zautomotive. It allows you to reprogram for the new tire size in the Jeeps computer. This will not only get your speedo reading correctly, but will also allow the 8-speed auto to readjust its shift points to as close to factory performance, shy of a regear.

A regear can easily cost about $2k in parts and labor. Most, including myself, would suggest that that money would be better spent by putting it towards a set of Rubicon take-off axles.

Choosing one of the lighter weight and smaller diameter 37's was a smart play. It's not just the taller 3.45 gearing that doesn't lend itself to larger tires, but the axles are overall smaller of housing and axle shaft diameter. A lead foot trying to race off the light with everyone else could result in twisted axle shafts or broken differential teeth down the line. Not saying it has to be driven like it's transporting crystal glassware, just that it shouldn't be whomped around.

As for lift kits, I'd honestly have gone another direction. If I didn't have Metalcloak, Rock Krawler would've made me just as happy. I only know that skyjacker is more rooted in the pickup world, but don't have any knowledge or experience with their products to make an opinion on them.

I will say though, that the true and full potential of one set of shocks and springs to another will only be fully realized when pushing the vehicle closer to its limits. Shy of that, even a more budget friendly combo could be an improvement over stock. In my opinion, it's having a quality set of lift supporting parts that makes the difference between a shotty ride and a nice ride, that could be felt by just pulling out of your neighborhood. Supporting parts include front and rear track bars, all 8 control arms, and steering linkages. If budget interferes with doing it all at once, it can be spread out, but the more beef that's added to the connection points between the axles and the frame/body, the more solid and planted the Jeep will feel both on and off road.
 
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Izzo93

Izzo93

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First off, I highly recommend getting the Tazer programmer from the company Zautomotive. It allows you to reprogram for the new tire size in the Jeeps computer. This will not only get your speedo reading correctly, but will also allow the 8-speed auto to readjust its shift points to as close to factory performance, shy of a regear.

A regear can easily cost about $2k in parts and labor. Most, including myself, would suggest that that money would be better spent by putting it towards a set of Rubicon take-off axles.

Choosing one of the lighter weight and smaller diameter 37's was a smart play. It's not just the taller 3.45 gearing that doesn't lend itself to larger tires, but the axles are overall smaller of housing and axle shaft diameter. A lead foot trying to race off the light with everyone else could result in twisted axle shafts or broken differential teeth down the line. Not saying it has to be driven like it's transporting crystal glassware, just that it shouldn't be whomped around.

As for lift kits, I'd honestly have gone another direction. If I didn't have Metalcloak, Rock Krawler would've made me just as happy. I only know that skyjacker is more rooted in the pickup world, but don't have any knowledge or experience with their products to make an opinion on them.

I will say though, that the true and full potential of one set of shocks and springs to another will only be fully realized when pushing the vehicle closer to its limits. Shy of that, even a more budget friendly combo could be an improvement over stock. In my opinion, it's having a quality set of lift supporting parts that makes the difference between a shotty ride and a nice ride, that could be felt by just pulling out of your neighborhood. Supporting parts include front and rear track bars, all 8 control arms, and steering linkages. If budget interferes with doing it all at once, it can be spread out, but the more beef that's added to the connection points between the axles and the frame/body, the more solid and planted the Jeep will feel both on and off road.
Very informative and appreciate the insight laid out. And the comment “Not saying it has to be driven like it's transporting crystal glassware, just that it shouldn't be whomped around” COMPLETELY made my night!!! Right on man 👍🏼🤣🤣🤘🏼Thanks again
 

Headbarcode

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Very informative and appreciate the insight laid out. And the comment “Not saying it has to be driven like it's transporting crystal glassware, just that it shouldn't be whomped around” COMPLETELY made my night!!! Right on man 👍🏼🤣🤣🤘🏼Thanks again
No problem. There's a lot of helpful and very knowledgeable people here, so don't hesitate to ask away. And welcome to the community, Nathan!
 

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So yes. I am going to be the despised “Mall Crawler” for the time being
Nathan. I responded on your other thread suggesting adjustable lower control arms. My Jeep is a mall crawler, pavement princess or whatever other name we use on here. I will provide my opinion of 37s on 3.45s. Around town with 8spd I think it has plenty of power (I’m old though :) ). On the highway you will never see 8th and seldom 7th. It hasn’t bothered me at all but I’m not on the freeway/interstate often. Would it be better, yes, but like Mike stated above - I would swap Rubi axles in before spending 2000-2500 on gears. The added benefit for 4.10s and lockers would be nice when needed. As for the lift components, it appears that kit gives you an adjustable front TB and relo bracket for rear. This is a good thing to get axles centered. The big issue I see, as mentioned, is the LCAs. Your caster will not be where you want it for better highway driving. Wife will not be happy with that. I will close with this. It is a Jeep thing, don’t be surprised if year from now you are swapping out lift components because you want to push it further in capabilities. Good luck with everything and welcome.
 

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ecowan1

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I just put 37x13.5 on my 19 Rubicon, it has the 2.0t. It is definitely noticeably slower but I expected that. It also does not want to hold 8th gear on the highway and going up hills at 25mph is 2nd gear at almost 4500 rpm. So what are some options, I have a taser to recalibrate my speedometer bury what else could i do, a tuner? a regear? air intake? i know a regear would help a lot but if i’d prefer not to if i don’t have to
 
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Izzo93

Izzo93

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I just put 37x13.5 on my 19 Rubicon, it has the 2.0t. It is definitely noticeably slower but I expected that. It also does not want to hold 8th gear on the highway and going up hills at 25mph is 2nd gear at almost 4500 rpm. So what are some options, I have a taser to recalibrate my speedometer bury what else could i do, a tuner? a regear? air intake? i know a regear would help a lot but if i’d prefer not to if i don’t have to
See I’m not sure. I was asking the same thing myself. Luckily you already have rubicon axels. So you are already a step ahead of me by having stronger axles. I have a JLU Sport which are smaller. Although you also have the 2.0t. While I have the 3.6. So many factors in to play there. I would refer to the previous reply’s people gave me. Everyone is recommending me getting the rubicon takeoffs and then re gearing to 4.88 or 5.13s. And my only issue isn’t re gearing on my end, I bought a 4” suspension lift, and it didn’t come with a heavy duty driveshaft or any control arms (which people are recommending I get all 8… these are some things to keep in mind
 

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See I’m not sure. I was asking the same thing myself. Luckily you already have rubicon axels. So you are already a step ahead of me by having stronger axles. I have a JLU Sport which are smaller. Although you also have the 2.0t. While I have the 3.6. So many factors in to play there. I would refer to the previous reply’s people gave me. Everyone is recommending me getting the rubicon takeoffs and then re gearing to 4.88 or 5.13s. And my only issue isn’t re gearing on my end, I bought a 4” suspension lift, and it didn’t come with a heavy duty driveshaft or any control arms (which people are recommending I get all 8… these are some things to keep in mind
Ok gotcha thanks! I was interested in the pros and cons between both (4.88 and 5.13s) if i do regear i want to regear for the best outcome possible so i was curious about any differences i’ll botox between the 2, but thanks for the help!
 

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My opinion on what direction to go:

Dana 30 front end.
If taken off road, no more than 35's. And you need to reinforce the housing a lot.
If not taken off road, 37's will work. Reinforcement wouldn't be a bad idea.

Rubicon Dana 44 front end.
If taken off road, 37's to 40's with full reinforcement.
If not taken off road, no reinforcement needed but it wouldn't hurt.

As far as gearing, the automatic transmission really does cover up a "less than optimal" gear ratio well. It will just shift a little differently to compensate and you may not get into 8th gear on the freeway. But you're still running at a good highway RPM in 6th and 7th so it's not so bad. I would put a regear in the "highly recommended" category though.

For the manual transmission behind the 3.6, I wouldn't put on bigger tires without a regear. I would even regear a non-Rubicon for stock tires but that's just me. A Rubicon with 4.10 gears is good for stock tires.

As far as what ratio to pick, a lot of it depends on what you're doing with the Jeep, where you live (high altitude vs low), and the size tires you're running.

I will say that I wouldn't bother going just one step (i.e. 3.54 to 3.73 or 4.10 to 4.56). The small change isn't worth the money. But if you make two steps or more, it's worth it.

At low altitude with stock tires and no off roading, 3.54 gears is probably adequate. 3.73 or 4.10 gears would be better Even 4.56 would be good if you do slow trails and/or rock crawling, especially with the manual transmission at high altitude.

For 35's, one step up would be ideal. So 3.73 gears would be minimum adequate setup

37's go the next step. 4.10's at least, with up to 5.13s.

40s would be best with at least 4.56s with up to 5.38s.

Of course, a dedicated trail rig could go beyond that and keep going up with shorter gears (higher numbers).
 
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Izzo93

Izzo93

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My opinion on what direction to go:

Dana 30 front end.
If taken off road, no more than 35's. And you need to reinforce the housing a lot.
If not taken off road, 37's will work. Reinforcement wouldn't be a bad idea.

Rubicon Dana 44 front end.
If taken off road, 37's to 40's with full reinforcement.
If not taken off road, no reinforcement needed but it wouldn't hurt.

As far as gearing, the automatic transmission really does cover up a "less than optimal" gear ratio well. It will just shift a little differently to compensate and you may not get into 8th gear on the freeway. But you're still running at a good highway RPM in 6th and 7th so it's not so bad. I would put a regear in the "highly recommended" category though.

For the manual transmission behind the 3.6, I wouldn't put on bigger tires without a regear. I would even regear a non-Rubicon for stock tires but that's just me. A Rubicon with 4.10 gears is good for stock tires.

As far as what ratio to pick, a lot of it depends on what you're doing with the Jeep, where you live (high altitude vs low), and the size tires you're running.

I will say that I wouldn't bother going just one step (i.e. 3.54 to 3.73 or 4.10 to 4.56). The small change isn't worth the money. But if you make two steps or more, it's worth it.

At low altitude with stock tires and no off roading, 3.54 gears is probably adequate. 3.73 or 4.10 gears would be better Even 4.56 would be good if you do slow trails and/or rock crawling, especially with the manual transmission at high altitude.

For 35's, one step up would be ideal. So 3.73 gears would be minimum adequate setup

37's go the next step. 4.10's at least, with up to 5.13s.

40s would be best with at least 4.56s with up to 5.38s.

Of course, a dedicated trail rig could go beyond that and keep going up with shorter gears (higher numbers).
My man.. yeah I appreciate it. Yeah so this is where I’m at right now. And not sure if you read Brett’s post or not but you could.
I currently am waiting for my lift to come in. I bought a 3.5”-4” suspension lift. It came with everything except any control arms. I opted to buy a dual rate steering stabilizer, and the coils are dual rate coils, and I opted for mono tube M95 shocks. I just purchased 17x9 fuel vapors, i also purchased 37” Ko2’s. I’m doing ZERO off-roading or rock crawling. This rig at least till the warranty is up is strictly going to be a Mall crawler / pavement princess. With that being said here is what I’m deciding.

the application of the Jeep will be two and from work as a daily driver. (7 minute commute one way, at background pavement speeds of 35-45 mph). And once I month I drive up North to camp (again all pavement, but this is all highway, at speeds ranging from 45-80mph). I was told ideally, I would want Rubicon Takeoff front and rear axles, and I would want them geared at 5.13. I was also told I want all 8 adj. control arms. I was also told I would want a beefier drive shaft probably an Adams one.

here is my current situation.

my lift will be in next week. And my wheels and tires are already in, so it’s simply me going to discount tire to have them mounted and balanced and slapped on.

money is tight atm, and I COULD if I had to take a loan out of my 401k to cover ALL the expenses ALTHOUGH, that isn’t ideal nor do I want to take that route.

could I put this lift on, and put the wheels and tires on, and just go? (The soonest I could get the adj control arms wouldn’t be for at least another 3 months to save up the money working some OT).

OR do I want to completely wait to put in my suspension lift, wait to put on the wheels and tires until I have enough money to buy all 8 control arms, buy a beefier drive shaft, and re gear? I’m itching to put on this suspension lift and wheel and tire combo as soon as possible, but if I’m going to completely destroy / damage other components I will have to exercise and practice some patience and wait.

here is my current rig, and I think it just simply looks God awful stock and don’t want to wait anymore.
Jeep Wrangler JL Do I need to regear / buy a new front axel / or truss reinforce? FF1E6A64-08B0-405B-8B3C-A178885B1E92
 

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grimmjeeper

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I waited to order everything at once (lift, wheels, tires, gears) before I did my upgrade on my JK sport. My new JL is on order and is a Rubicon and I'm not planning on any major lift/tires. Just dealer installed 35's with stock height and gears. But if I was going to do the same thing to this Jeep with lift/wheels/tires/etc., I'd wait again. But that's just what I would do.

But there's really no reason you can't do the upgrades in stages. Going big on tires without regearing will be something you notice but may not be so bad in your opinion and may affect how badly you want to get gears done.

I would absolutely recommend not doing a 401K loan for anything but an emergency. Either do the upgrade as parts come in or just wait until you have everything and do it all at once, whichever you prefer.
 

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I just put 37x13.5 on my 19 Rubicon, it has the 2.0t. It is definitely noticeably slower but I expected that. It also does not want to hold 8th gear on the highway and going up hills at 25mph is 2nd gear at almost 4500 rpm. So what are some options, I have a taser to recalibrate my speedometer bury what else could i do, a tuner? a regear? air intake? i know a regear would help a lot but if i’d prefer not to if i don’t have to
You can try a tune. The Diablo or Superchips tune makes a pretty nice difference on the 2.0T motor. The Diablo device also tunes the trans which makes it feel even better. I think the Superchips device has trans tuning coming if it's not there already. Peak gains aren't huge from what I remember, but but mid range and torque management are greatly improved. I don't drag race my jeep so I couldn't tell you how it feels at peak rpm/power. Drivability is great though. Big difference leaving from a dead stop. I drove a 19 JLUR 2.0T with 35s and 20" rims that had the Diablo/Superchips tune. It felt much peppier than my stock 20 JLUR 2.0T.
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