Re gear question

GOOSE3

Member 2024
I am sure this has been answered a ton, so I apologize in advance, but I have the factory 3.21 gears and want to re-gear at some point, so I wanted to get an idea about which route to take. I have the 2017 JKU with 35's, front/rear bumpers, and a winch, and want to get it back to the factory-ish power, it isn't bad too but searches for gears quite a bit and I don't want to damage anything. I dont have the money at the moment but when the time comes I want to be prepared. Based on a chart that was shared in another post, and the fact that I know almost nothing about this, I was leaning towards 4.10 as it is a DD and don't offroad much at all, and when I do, it won't be anything crazy.
 
Transmission use W580/NAG1
Tcase use NP 231... and you can play with gear ratios.

3.21 gearing is really tall. I would say look at 4.56 for drivability or 4.88 gearing for power . It is a brick so fuel mileage will realisticly be around 15-20MPG depending on how you drive.

My rig I went to 4.88 on BFG 37s ( Really a 35.5 tire) and was happy with the performance. Fuel mileage was around 17-18mpgs.

To have a shop do the gears , gear set with a master install kit runs around $600.00. Add to that 8 hours for labor on each axle Most shop rates are $100.00 ish an hour some as much as $150.00. so factor in Labor at $800-$1200 per axle. times 2 axles. It is a hefty bill.

Alternative is to have a friend with the tools and have a garage party and do the install yourself. $1400.00 for a wrenching party and 8-12 hours vs
$4000 for a shop to do the work.
 
I agree with Rob, I would lean to 4.56 or 4.88. I did 5.13 in my Jeep running 37' tires, realistically 36ish and it a little punchier than factory was. Bullrun did mine and it was under $3k with reprogramming
 
I would agree with 4.56 gears to get you to drivability. I would definitely shop around for shops in your area. I think you will probably find most places are fairly close to each other on price. I would definitely disagree with a garage party and doing it yourself. Some feel they have the ability and have even done it in the past but it doesn't take much for a catastrophic failure that will end up costing much more. With a shop doing it, if something goes wrong you can go back to the shop. IMO the cost is well worth knowing it is done right and you have the gear and work warranty.
 
I had 4.10 on my JKUR with true 35s and I would say it was slightly anemic. I would have to drop a couple of gears just to pull small rolling hills on 211. Ran it this way for about 40k miles because I preferred to keep my RPMs lower on the highway and had enough power in Lo range for the trails I do. If I were to pay to have gears done, I'd go with the 4.56. If your jeep doesn't see much highway time or you think you may go bigger at some point (which will require further work to your axles), then 4.88s. If you decide to go with 4.1, another option would be to find some rubicon takeoff axles that are factory geared 4.10 and just bolt them up. Two stock rubicon axles should run you significantly less than the cost of a regear at a shop.
 
Don't forget an added expense no one has mentioned yet, To go up in gears anywhere in the 4.xx range, you're going to have to change your differntial carriers as well, (Or use Thick gear sets). If you just stay open that will only add about $200, but if you think you'll ever want any kind of locker, this is the time to do that too...
 
Thanks guys, I will look into the 4.56 gears and carriers too. I would never attempt to take on a project like this nor do I have any buddies that are capable, so I will look around at shops and also look around for possible wrenching parties that can help. I need to price out the parts and get the cost sorted then get the money together. The longest drive I make is to St Michael's from Great Falls, so highway driving isn't a big concern.
 
You have already arrived at a great conclusion but here is a good chart from Yukon that that helps drive home the relationship between tire diameter and gear ratio. 4.56 is great for getting back to that more stock feeling, and a 4.88 would get you a bit more performance at the cost of fuel economy.

1674699925307.png
 
interesting chart, What gear are they using and for what MPH? Looks like 1:1 or fourth gear on a NAG1
 
Don't forget an added expense no one has mentioned yet, To go up in gears anywhere in the 4.xx range, you're going to have to change your differntial carriers as well, (Or use Thick gear sets). If you just stay open that will only add about $200, but if you think you'll ever want any kind of locker, this is the time to do that too...
I did leave out the carriers in my ROM. thanks Zuke.
 
Garage party, While some disagree and are put off by a lack of warrantee It is just a mechanical operation. A good understanding of how and what needs to be done and it is well within a competent mechanics ability to achieve. Warrantees are not worth the paper most are written on. I have heard shops not stand by their work and blame the customer for the issues that happen and flat out give bad advise.

One thought on this is have the dealer ship re-gear the rig. if there is a factory or extended warrantee on your rig having the dealer do the work will not void what is left of it. You are paying dealership prices but have OEM parts being installed.

Lots of shops do gears. Talk with folks that have had work done by the shops you are thinking of. You get what you pay for. While not in the area East Coast Gear and supply has a drive in service. I can attest that they stand behind their work. And the cost is reasonable as well. The one shop I would recommend in the are is very expensive. The rest have good days and bad.

Good luck wiht you project.
 
Garage party, While some disagree and are put off by a lack of warrantee It is just a mechanical operation. A good understanding of how and what needs to be done and it is well within a competent mechanics ability to achieve. Warrantees are not worth the paper most are written on. I have heard shops not stand by their work and blame the customer for the issues that happen and flat out give bad advise.

One thought on this is have the dealer ship re-gear the rig. if there is a factory or extended warrantee on your rig having the dealer do the work will not void what is left of it. You are paying dealership prices but have OEM parts being installed.

Lots of shops do gears. Talk with folks that have had work done by the shops you are thinking of. You get what you pay for. While not in the area East Coast Gear and supply has a drive in service. I can attest that they stand behind their work. And the cost is reasonable as well. The one shop I would recommend in the are is very expensive. The rest have good days and bad.

Good luck wiht you project.
I actually like wrenching or getting together for projects on cars, houses, and any other types of work. Great way to help others and have a good time, when I lived in Louisiana my friends and I got together often to work on each other's projects. Some of the best times I have ever had.
 
I don't feel like a regear is mandatory with my 4.10s/8 speed/turbo. But part of me just wants to perform a regear for the experience. It looks like a fun project. The JL forum has some detailed guides, and fairly good troubleshooting steps. I'd imagine there are similar threads out there for the JK.

If I were to regear I'd pick 4.88s for my 37s. WIth the extreme recon package, Jeep is pairing 4.56s with 35s from the factory. 4.56 sounds like a good choice for your 35s.
 
I don't feel like a regear is mandatory with my 4.10s/8 speed/turbo. But part of me just wants to perform a regear for the experience. It looks like a fun project. The JL forum has some detailed guides, and fairly good troubleshooting steps. I'd imagine there are similar threads out there for the JK.

If I were to regear I'd pick 4.88s for my 37s. WIth the extreme recon package, Jeep is pairing 4.56s with 35s from the factory. 4.56 sounds like a good choice for your 35s.
Big Delta in performance between the NAG1 and the 850re. While the JL trans (8 speed) is more tolerant of gearing mismatch the JK NAG1 (5 speed) benefits greatly from the gearing change in both performance and longevity.
 
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