MC 2.5 or 3.5 Game changer Question

Snowblind

Jeep Owner
I'm glad I found this forum. I've been eyeing the MC kits and trying to decide between the 2.5 and 3.5 for my new-to-me 16 Rubi JKU. I had a 2.5 Rough Country lift (don't ask) on my 13 JKU sport, and seeing the pictures of the 2.5 MC lift, you can tell it's way more lift that the Rough Country. I was planning on 37s, but you guys on 35s look solid too. In short... I'm still torn between 2.5 and 35s and 3.5 and 37s... 😂
 

Pthorpe84

Moderator
Staff member
I'm glad I found this forum. I've been eyeing the MC kits and trying to decide between the 2.5 and 3.5 for my new-to-me 16 Rubi JKU. I had a 2.5 Rough Country lift (don't ask) on my 13 JKU sport, and seeing the pictures of the 2.5 MC lift, you can tell it's way more lift that the Rough Country. I was planning on 37s, but you guys on 35s look solid too. In short... I'm still torn between 2.5 and 35s and 3.5 and 37s... [emoji23]
You can easily run the 37’s on the 2.5” lift. Just get the bumpstops correct. I’m stock on 37’s. Heck, with enough trimming, 40’s would work fine.

Honestly 35’s and 2.5” will do just about anything you would want to do on a trail. Plus save you a ton of money. Just make sure you reinforce your c’s.


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Snowblind

Jeep Owner
You can easily run the 37’s on the 2.5” lift. Just get the bumpstops correct. I’m stock on 37’s. Heck, with enough trimming, 40’s would work fine.

Honestly 35’s and 2.5” will do just about anything you would want to do on a trail. Plus save you a ton of money. Just make sure you reinforce your c’s.


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Yeah, some of the guys in the club around here are in a height war. One just went to a 6" long arm, coilover conversion, getting ready for 40s. Me, I'm looking for a nice daily driver, that can wheel when I get time. A friend of mine has wheeled all over the place, on some of the best known trails with a 2.5 and 35s. I just like the looks of 37s. I may still go 37s, and stick with the 2.5 and good flat fenders to help clear that tall shoe.

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Pthorpe84

Moderator
Staff member
Yeah, some of the guys in the club around here are in a height war. One just went to a 6" long arm, coilover conversion, getting ready for 40s. Me, I'm looking for a nice daily driver, that can wheel when I get time. A friend of mine has wheeled all over the place, on some of the best known trails with a 2.5 and 35s. I just like the looks of 37s. I may still go 37s, and stick with the 2.5 and good flat fenders to help clear that tall shoe.

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Hey man. Cut those stock Fenders or get some MC overlines, 2.5” lift, and some 37’s. You will be a beast on the trails and on the asphalt. 37’s look amazing on LCOG builds.

What gears are you running? If they are 3:21’s...either regear or stick with 35’s.


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Snowblind

Jeep Owner
Hey man. Cut those stock Fenders or get some MC overlines, 2.5” lift, and some 37’s. You will be a beast on the trails and on the asphalt. 37’s look amazing on LCOG builds.

What gears are you running? If they are 3:21’s...either regear or stick with 35’s.


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Luckily, this ole girl came with 4.10s, so gearing won't be a huge issue. Yeah, some say go 4.56-4.88s, but 4.10s will turn 37s all day long.

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Snowblind

Jeep Owner
Hey man. Cut those stock Fenders or get some MC overlines, 2.5” lift, and some 37’s. You will be a beast on the trails and on the asphalt. 37’s look amazing on LCOG builds.

What gears are you running? If they are 3:21’s...either regear or stick with 35’s.


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And I don't know about trimming painted fenders.


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Brian

Jeep Fanatic
Luckily, this ole girl came with 4.10s, so gearing won't be a huge issue. Yeah, some say go 4.56-4.88s, but 4.10s will turn 37s all day long.

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I have stock 4.10 gears on a rubicon with 35's and for me, that is as large of tire as I would go on 4.10. I still hate getting on the highway when it is windy as it will not hold high gear. I have an automatic.

I would do 4.88's with 37's.

My Jeep is also pretty heavy with bumpers, winch, skids and gear.

All in all, I have the same Jeep you do, White, Rubicon, but I have black fender flares and mine is a Hard Rock.
 

Snowblind

Jeep Owner
I have stock 4.10 gears on a rubicon with 35's and for me, that is as large of tire as I would go on 4.10. I still hate getting on the highway when it is windy as it will not hold high gear. I have an automatic.

I would do 4.88's with 37's.

My Jeep is also pretty heavy with bumpers, winch, skids and gear.

All in all, I have the same Jeep you do, White, Rubicon, but I have black fender flares and mine is a Hard Rock.
Yeah, I had a lot of heavy stuff on my 13 Sport, and it was a slug even on 33s. I'm going to keep this one as light and simple as possible. The guy that had the new Jeep before me put a large bumper on the front, and I've already looked into replacing it with a lighter subby. I'm going to approach this with a KISS build, Keep It Simple Stupid.

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Snowblind

Jeep Owner
Trim them them coat with Monstaliner. Going to do mine in November.
I have thought of either coating/painting them black, or removing the black paint from the top to match the rest of the Jeep. It shall be named, Snowblind. Yes, I'm an old Styx and Black Sabbath fan.

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SSinGA

Jeep Fanatic
I have thought of either coating/painting them black, or removing the black paint from the top to match the rest of the Jeep. It shall be named, Snowblind. Yes, I'm an old Styx and Black Sabbath fan.

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Monstaliner Prob has a white that will match.
 

SCREAMER

Jeep Newb
4.88 and 37's are perfect for a manual. 5.13 if it is a auto.
I know that a lot of this is just personal opinion and preference but I had 35s on my ‘14 sport automatic with 3.73 gears and it had plenty of scoot even with added armor all around. My current JKU Recon now has 35s and 4.10 gears with a manual and feels plenty strong even on the freeway. I did install an intake and exhaust on both and felt that those mods improved power and mileage. I’d love to drive a 3.6 JKU with 4.88s and 35s or 37s just to see the difference but as my Jeep sits now, I feel it completely unnecessary to swap to a higher ratio. The 3.6 pentastar is such a great motor, I can see why it’s carrying over into the JL. I know the older 3.8 was a completely different story and needed all the gearing it could get to push big rubber. Plenty of guys around here with 3.8s running 5.13 just to push 35s. You know your geared high when your city mileage is 5-6 mpg better than your highway mileage. 😂
 

Snowblind

Jeep Owner
I know that a lot of this is just personal opinion and preference but I had 35s on my ‘14 sport automatic with 3.73 gears and it had plenty of scoot even with added armor all around. My current JKU Recon now has 35s and 4.10 gears with a manual and feels plenty strong even on the freeway. I did install an intake and exhaust on both and felt that those mods improved power and mileage. I’d love to drive a 3.6 JKU with 4.88s and 35s or 37s just to see the difference but as my Jeep sits now, I feel it completely unnecessary to swap to a higher ratio. The 3.6 pentastar is such a great motor, I can see why it’s carrying over into the JL. I know the older 3.8 was a completely different story and needed all the gearing it could get to push big rubber. Plenty of guys around here with 3.8s running 5.13 just to push 35s. You know your geared high when your city mileage is 5-6 mpg better than your highway mileage. [emoji23]
Gearing is give and take, and finding that happy medium can be a challenge. We have a few guys around here with 4.10s rolling on 37s, and like it for the most part. One is planning 4.88s soon, but says he's in no rush. As for 35s and 4.10s, most wheelers around hear say that's the perfect combo. The big complaint I hear from the guys on 37s is stopping, not starting.

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Brian

Jeep Fanatic
Ome thing missing from this gearing topic is the weight of the rims and tires people are using. While most 35's are heavy, some are heavier! Rims go the same way with cheaper trims normally being heavier. The more rotational mass means a slower start and slower stop.

Also, my summer daily driver is a modified Mustang GT, so turtle slow is not something I want to deal with. I will tell you that my 06 TJ Rubicon with 33's and a manual is MUCH faster than my JKU with 35's and an auto.

So, if you came from a Honda Civic, one might be happy with stock gearing. If you want to keep the stock power, one MUST re-gear.

IMHO, do not read much on peoples opinions on gearing. Ask this to yourself: Are you willing to settle for a significant decrease in power with larger tires? If you are, keep the gears. If you want to keep the same performance, you must change the gears.
 

Snowblind

Jeep Owner
Ome thing missing from this gearing topic is the weight of the rims and tires people are using. While most 35's are heavy, some are heavier! Rims go the same way with cheaper trims normally being heavier. The more rotational mass means a slower start and slower stop.

Also, my summer daily driver is a modified Mustang GT, so turtle slow is not something I want to deal with. I will tell you that my 06 TJ Rubicon with 33's and a manual is MUCH faster than my JKU with 35's and an auto.

So, if you came from a Honda Civic, one might be happy with stock gearing. If you want to keep the stock power, one MUST re-gear.

IMHO, do not read much on peoples opinions on gearing. Ask this to yourself: Are you willing to settle for a significant decrease in power with larger tires? If you are, keep the gears. If you want to keep the same performance, you must change the gears.
Exactly. That's why I have planned to use the lightest stuff I can find, without sacrificing durability. Aluminum is a great option for flares and even bumpers. My friend is a serious crawler, has a heavily modified rig, and he runs aluminum wherever possible. Now, his skids are steel, as is his sliders and armor, but he switched to a aluminum bumpers and flares and said it made a huge difference in overall performance, and ability to slow the rig during steep decent.

Like when I was building my AR-15, a guy gave me some good advice to keep it light. "Remember, ounces quickly turn into pounds." By saving just a few ounces here and there, I was able to keep it light, and extremely easy to handle.

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SCREAMER

Jeep Newb
If you want to keep the stock power, one MUST re-gear.

IMHO, do not read much on peoples opinions on gearing. Ask this to yourself: Are you willing to settle for a significant decrease in power with larger tires? If you are, keep the gears. If you want to keep the same performance, you must change the gears.
I guess this was one of the points I was trying to make but wasn’t really clear on. My ‘14 sport with an auto and 3.73s only had a minor drop in acceleration and MPGs after switching to 35s. After wheeling it a couple times and driving it around for a week or so, I couldn’t really remember any difference and felt that the stock gearing was just fine. My current Jeep, a ‘17 Recon, came with 4.10s and after the swap from the stockers to 35s, I could not tell a difference at all in acceleration performance and only lost about 1-2 MPGs. This is the reason I’d love to test drive a 3.6 JKU with 35s-37s and 4.88-5.13 gears. Just so I could see what the difference really feels like. I’ve had plenty of fast cars in my time so I’ve had a taste of performance and I never felt like either of my JKs were too slow to get out of their own way. They’re not winning any races but they’re definitely not near as slow as some of the “economy” cars I have owned and driven.

Does anyone have any links to videos of back to back or side by side tests of JKs that had gear swaps done or any comparisons of what we’re talking about? I’d love to line up next to one like mine with the only difference being gearing.
 

Snowblind

Jeep Owner
I guess this was one of the points I was trying to make but wasn’t really clear on. My ‘14 sport with an auto and 3.73s only had a minor drop in acceleration and MPGs after switching to 35s. After wheeling it a couple times and driving it around for a week or so, I couldn’t really remember any difference and felt that the stock gearing was just fine. My current Jeep, a ‘17 Recon, came with 4.10s and after the swap from the stockers to 35s, I could not tell a difference at all in acceleration performance and only lost about 1-2 MPGs. This is the reason I’d love to test drive a 3.6 JKU with 35s-37s and 4.88-5.13 gears. Just so I could see what the difference really feels like. I’ve had plenty of fast cars in my time so I’ve had a taste of performance and I never felt like either of my JKs were too slow to get out of their own way. They’re not winning any races but they’re definitely not near as slow as some of the “economy” cars I have owned and driven.

Does anyone have any links to videos of back to back or side by side tests of JKs that had gear swaps done or any comparisons of what we’re talking about? I’d love to line up next to one like mine with the only difference being gearing.
My 13 sport had 3.21 and 33s. With all the heavy stuff I added, it was a slug, and breaking was awful. No matter what I run this time around, I will be upgrading the breaks.

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Brian

Jeep Fanatic
I guess this was one of the points I was trying to make but wasn’t really clear on. My ‘14 sport with an auto and 3.73s only had a minor drop in acceleration and MPGs after switching to 35s. After wheeling it a couple times and driving it around for a week or so, I couldn’t really remember any difference and felt that the stock gearing was just fine. My current Jeep, a ‘17 Recon, came with 4.10s and after the swap from the stockers to 35s, I could not tell a difference at all in acceleration performance and only lost about 1-2 MPGs. This is the reason I’d love to test drive a 3.6 JKU with 35s-37s and 4.88-5.13 gears. Just so I could see what the difference really feels like. I’ve had plenty of fast cars in my time so I’ve had a taste of performance and I never felt like either of my JKs were too slow to get out of their own way. They’re not winning any races but they’re definitely not near as slow as some of the “economy” cars I have owned and driven.

Does anyone have any links to videos of back to back or side by side tests of JKs that had gear swaps done or any comparisons of what we’re talking about? I’d love to line up next to one like mine with the only difference being gearing.
Your 2017 with 4.10's is the same situation that I has with my 2015 with 4.10's. After a proper break in, I could easily spin the tires on my Jeep from a stop. My shifts were consistent at 2,500 rpm's in normal traffic. Once I switched to 35" Yokahama MT's, I could no longer turn the tires from a stop. My shifts in normal traffic have increased to 3,000 rpm to go the same speeds and on the highway, while traveling into a 20 mile an hour wind, I cannot hold overdrive.

My point was to simply say, if you want to keep the stock performance, one must re-gear. Everyone notices things differently in cars and you do not see/feel a difference, but we know there is. One cannot add a much larger diamerter tire that is heavier to a car wihout changing anything and have it perform the same.

The good news for you is that you are happy with your jeep and do not need to spend the money on gearing! It does not get any better than that my friend. Some people do not want to take that power decrease.

If I get a chance, in december, I will try to throw my Jeep on my machinists dyno and show you that there is a significant power loss with larger tires and show the drop in HP to the rear wheels. We can show it in the graph and also in the time it takes the engine to spin the tires to 80mph.
 
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