Ordering 4.88 Gears

[Whaler27]

East Coast Gear Supply is the best place to get them. Use PC2021 to get 10% off the cost.

If you are ever thinking that you want to go to 37's, seriously consider going 5.13 on the gearing.

I prefer the 488s with 37’s on the JL. Seems like the perfect balance. On the TJ I would have needed 513s, at least.

You can spend a lifetime reading debates about the “right” gear ratio for any particular tire size. In the end it distills to personal preference in the context of your use profile. If you ‘re a rock crawler the balance is very different from the guy who wants to overland, but also use his Jeep as a commuter.

If you like the balance of power and fuel economy with OEM 34” tires and 4.10 gears, then you’ll like the balance with 4:88s and 37” tires. All things being equal, that combination (488s with 37s) will produce slightly higher RPM levels for any given speed, but it will be pretty close, and a few extra RPMs is nice to have when turning the extra weight. For perspective, assuming no interference/contribution from the transmission changing the gear selection, 488s with 39“/40” tires are a closer match for OEM (34” and 410) RPM level at any given speed, but there are other physics in play which absorb energy and change that balance.

I‘m not a rock crawler, but I go through little patches of challenging rock garden, and the JL does just fine on 37s with OEM gears. Still, I’m going to follow my brother to 488s because it will make the top gear more accessible, improve low end grunt, and, hopefully, retain existing fuel economy. I have zero interest in 513s.

One more thought, the pinion head gets a little smaller as you transition from 488 to 513 and up. Some suggest that results in loss of durability with each step. I doubt there’s much difference, at least through the low 5s, as the same number of teeth are in contact with the ring at any given time. Still, equivalent forces on slightly smaller teeth has got to have some impact on gear life, even if small. That, and the inevitable loss in fuel economy, makes me even happier with the 488 balance.

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[CarbonSteel]

I prefer the 488s with 37’s on the JL. Seems like the perfect balance. On the TJ I would have needed 513s, at least.

You can spend a lifetime reading debates about the “right” gear ratio for any particular tire size. In the end it distills to personal preference in the context of your use profile. If you ‘re a rock crawler the balance is very different from the guy who wants to overland, but also use his Jeep as a commuter.

If you like the balance of power and fuel economy with OEM 34” tires and 4.10 gears, then you’ll like the balance with 4:88s and 37” tires. All things being equal, that combination (488s with 37s) will produce slightly higher RPM levels for any given speed, but it will be pretty close, and a few extra RPMs is nice to have when turning the extra weight. For perspective, assuming no interference/contribution from the transmission changing the gear selection, 488s with 39“/40” tires are a closer match for OEM (34” and 410) RPM level at any given speed, but there are other physics in play which absorb energy and change that balance.

I‘m not a rock crawler, but I go through little patches of challenging rock garden, and the JL does just fine on 37s with OEM gears. Still, I’m going to follow my brother to 488s because it will make the top gear more accessible, improve low end grunt, and, hopefully, retain existing fuel economy. I have zero interest in 513s.

One more thought, the pinion head gets a little smaller as you transition from 488 to 513 and up. Some suggest that results in loss of durability with each step. I doubt there’s much difference, at least through the low 5s, as the same number of teeth are in contact with the ring at any given time. Still, equivalent forces on slightly smaller teeth has got to have some impact on gear life, even if small. That, and the inevitable loss in fuel economy, makes me even happier with the 488 balance.

With any engine other than the 3.6L I would agree, but with the 3.6L and 37's and all of the things that go with it (lift kit, skid plate, which, heavy tires, heavy wheels, etc.), 5.13 would be the way to go.

I already re-geared to 4.88 and will be looking to supercharge it in the coming months. The 7K increase in altitude after I moved pretty much killed my performance.

 

[Whaler27]

With any engine other than the 3.6L I would agree, but with the 3.6L and 37's and all of the things that go with it (lift kit, skid plate, which, heavy tires, heavy wheels, etc.), 5.13 would be the way to go.

I already re-geared to 4.88 and will be looking to supercharge it in the coming months. The 7K increase in altitude after I moved pretty much killed my performance.

The altitude makes a difference. My brother lives near Glenwood Springs. His house is at 7800 feet, but he’s got the 2.0, and turbos mitigate the negative impact of altitude. For him, the 488s are perfect.

Most of my trail riding in Oregon is below 2500’, but I‘m occasionally over 5,000, and I try to visit Colorado to play with my brother once per year. (My avatar on this site was taken near Aspen at about 9,000’.) My Jeep is over 6000 pounds as equipped/loaded, and I have never felt underpowered running the stock 410s with 37 KO2s, but part of that is probably my use (little real rock crawling), and my recent context. My last Jeep, which I kept for the first 18 months I owned the JL, was a 2006 TJ Sport with a 6-speed, 33s, and 456s, so I was used to managing everything with a MUCH less powerful vehicle. The JL is a powerhouse by comparison, even loaded down and burdened by the 37s. Really, I’m happy where it sits, but I think it will be better with the 488s, and I’m addicted to screwing with the Jeep. (Any recommendations on where to buy gear sets? I’m not having any luck searching the forum with that query.)

I just ordered Alcon brakes off of Amazon. They were about $400 cheaper than buying them directly from Alcon PLUS I saved almost $300 in shipping charges.

 

[CarbonSteel]

The altitude makes a difference. My brother lives near Glenwood Springs. His house is at 7800 feet, but he’s got the 2.0, and turbos mitigate the negative impact of altitude. For him, the 488s are perfect.

Most of my trail riding in Oregon is below 2500’, but I‘m occasionally over 5,000, and I try to visit Colorado to play with my brother once per year. (My avatar on this site was taken near Aspen at about 9,000’.) My Jeep is over 6000 pounds as equipped/loaded, and I have never felt underpowered running the stock 410s with 37 KO2s, but part of that is probably my use (little real rock crawling), and my recent context. My last Jeep, which I kept for the first 18 months I owned the JL, was a 2006 TJ Sport with a 6-speed, 33s, and 456s, so I was used to managing everything with a MUCH less powerful vehicle. The JL is a powerhouse by comparison, even loaded down and burdened by the 37s. Really, I’m happy where it sits, but I think it will be better with the 488s, and I’m addicted to screwing with the Jeep. (Any recommendations on where to buy gear sets? I’m not having any luck searching the forum with that query.)

I just ordered Alcon brakes off of Amazon. They were about $400 cheaper than buying them directly from Alcon PLUS I saved almost $300 in shipping charges.

East Coast Gears is the best place to buy them. Use code PC2021 and save 10%. Will at East Coast Gears goes above and beyond and will answer any and all questions.

 

[mnjeeper]

, I might not even want to jump up to 35s. Either way I couldn’t pass on the opportunity.

You won't have to jump when they are part of the package to get the 4.88 gears.

 

[vasdimpop]

I've got a manual JLUR on order and didn't get the 4:88 gears; how bad should I be regretting it? Are the benefits here for crawling or for overall performance on street/off-road?

I'm not planning on going to a lift or bigger tire size until warranty is up probably...

 

[Jmos4]

I've got a manual JLUR on order and didn't get the 4:88 gears; how bad should I be regretting it? Are the benefits here for crawling or for overall performance on street/off-road?

I'm not planning on going to a lift or bigger tire size until warranty is up probably...

Hi,

You should be getting 4.10's so will be fine for 33's maybe even 35's, my wife's 2015 JKUR has 4.10's and 32's and is quick and fun plenty of power so you should be fine, I ordered my 22 with 4.88's as planning on 35's down the road.

Regards,
Jim

 

[AcesandEights]

I've got a manual JLUR on order and didn't get the 4:88 gears; how bad should I be regretting it? Are the benefits here for crawling or for overall performance on street/off-road?

I'm not planning on going to a lift or bigger tire size until warranty is up probably...

I think with stock tires, even 35" tires, the gears are low for on-road/highway driving. The stock Rubicon has 4.1 gearing and mine runs a little over 2k RPM (close to 2,200) at 70 mph. 4.88 at 70 mph would be almost 20% higher RPM. So, you'd be running down the highway (at 70 mph) at about 2,600 RPM with stock tires. 35" tires are six percent taller, so you could expect roughly a six-percent reduction in RPM with the taller tires. So, you'd be running approximately 2,450 RPM at 70 mph with 35" tires and 4.88 gearing. That's in sixth gear. Of course, increase your speed to 75 (77 mph would be 10% higher RPM), or lower it and you increase/decrease your RPM accordingly.

 

[Really?AJeep?]

I successfully changed my order and got the 4.88's once I realized they were an option. Plan on driving the Jeep home, then to a friend's shop the next day for 35" tire swap. The only regrets I've ever had on my 4x4's was not getting low enough gears, and I'd rather have them from the factory than having to do them myself. Should make a 2 door manual pretty fun to drive! ?

 

[Industrialwrench]

I’d be more than pleased if my Jeep showed up with 35’s. Unfortunately I know it’s not going to happen. There’s nothing planned for the 2doors and 35’s.

 

[luthert]

Have any of y’all received y’all’s builds yet? Wondering how well the 4.88s do on the stock tire… just ordered A 2022 Rubicon with them… 15 week estimated build time.

 

[baskiboat]

I've not had an automatic wrangler before. Will 4.88 and 37's in a rubicon crawl without touching the gas? My manual TJ did with 35's and 4.56's and I really liked the option to go slow and limit spin when floating over deep snow.

 

[AcesandEights]

The 1st gear ratio is different between the two, so you'd want to do the math to see what the effective crawl ratio (including the larger tire) would be.

 

[Jmos4]

Hi all,

My 22 JLUR 6mt 4.88's, ordered 11-29, came in on Wednesday 3-8, picked up Thursday and Saturday proceeded to add 35's and a few other things:

With 35's:

Drove the same, one thing to note driving with 33's 1st gear is very short, although not short enough to use 2nd to start in except on a roll, with 35's at least you can get through a intersection without having to shift, also just getting use to it.

Regards,
Jim

 

[AcesandEights]

Got my 2022 yesterday. Put 500 miles on it yesterday and it's noticeable over the 4.10 stock gearing. Keeps the RPM around 2,500+ on the hwy. It crawls in 1st like nobody's business.

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