3.21 gears - not that bad?
12-15-2012, 10:13 PM
#41
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Hmmmm, they must of made changes to the gear ratios in the transmissions in 2013, cause now I'm all confused.
12-16-2012, 02:32 AM
#42
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I'd go with the 3.73s I actually think they get better mileage than the 3.21 seems like most people are getting 18mpgs with the 3.73 and 16-17 with the 3.21 I have a 2012 rubicon with 4.10s 6spd and on long highway trips I average 19-21 depending on hills rpms are about the same as a 3.73 auto at 70mph
12-16-2012, 03:27 AM
#43
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I average 18 with 3.21 and automatic with my 2012 Sahara. My best on the highway was 23.5mpg with the cruise on at 60mph. That was on a 120 mile road trip. I'm going with a 295-70-17 tire this spring (33.4 inch tire) so I'm contemplating on switching to 3.73 or 4.10 so the RPM range stays around 2000. One guy said he has 3.73 and his rpm is at 2500 at 70mph. I clicked my automatic into 4th and I'm at 2400 which definitely is to high. I guess I'm just going to see how much I lose when I go with the little bit bigger tire.
12-16-2012, 04:59 AM
#44
I've got a manual 2010 JK Sport with 3.73 gears, and I'm looking to replace it with a 2013 JKU Sport. I figured I'd grab all the same options as before (same packages, trailer tow kit, etc), but this newer engine has me second guessing gear ratios. I test drove a manual JKU with 3.21 gears tonight, and I was really impressed with the performance of the Jeep. It felt much more responsive and powerful than my 2dr 3.8L with 3.73s. Up until now, I'd heard nothing but horror stories of the 3.21s, that they bog the Jeep down and make it sluggish, but it felt in every way better than my current setup.
Has the Pentastar made 3.21 gears viable, or has the wool been pulled over my eyes? I figure it's sufficient for daily driving with mild off road use and [potentially, on rare occasion] low weight towing (jet skis, maybe a Uhaul trailer), and that I'll end up changing the gears in the future anyhow if/when I finally overhaul the suspension with new axles and larger tires.
It's not that it's that expensive to get the 3.73s, but I figure there's no sense in buying what I won't use. What say you?
Has the Pentastar made 3.21 gears viable, or has the wool been pulled over my eyes? I figure it's sufficient for daily driving with mild off road use and [potentially, on rare occasion] low weight towing (jet skis, maybe a Uhaul trailer), and that I'll end up changing the gears in the future anyhow if/when I finally overhaul the suspension with new axles and larger tires.
It's not that it's that expensive to get the 3.73s, but I figure there's no sense in buying what I won't use. What say you?
Going from 3.73 to 3.21 you loose ~14% .
The power increase from the 3.8L to 3.6 Pentastar is ~42% .
The power increase that you felt is (42 - 14 = ) 28% .
This is not an accurate calculation because torque hasn't been considered, but it gives an idea of what's going on here.
If you take the 3.73, you'll have the entire 42% power increase (14% more than with 3.21).
You'll also have somewhat better mpg.
14% power increase AND better fuel consumption is, so I think, worth it.
Last edited by GJeep; 12-17-2012 at 01:16 AM.
12-17-2012, 03:06 AM
#45
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I'd double check your ratio you have cause I was doing 70mph at just over 2000 rpm's, and I'm 100% positive I have 3.21 as I visually checked the day I got it.
12-17-2012, 04:02 AM
#46
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I ordered mine with 3.73's and kinda regret it, 2400rpm at 70 is overkill, I think I'd be happier and richer with the 3.21's. It's been touched on many times before that you can easily run 33's with a Pentastar and either transmission. If heavy towing or high altitude is a factor go with 3.73's.
Also, I must admit that i think post about 3.21's not being matched to the 1st gear of the six speed is crazy. 4.46 is one of the lowest first gears available and is very generous to the offroad set.
Also, I must admit that i think post about 3.21's not being matched to the 1st gear of the six speed is crazy. 4.46 is one of the lowest first gears available and is very generous to the offroad set.
12-17-2012, 04:08 AM
#47
ive got a 2 door, 6 speed manual w/ 3.21's and i wouldnt do it again....i believe id have been much happier w/ 3.73s in stock form.
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
Last edited by bushpilot; 12-17-2012 at 04:11 AM.
12-17-2012, 04:20 AM
#48
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ive got a 2 door, 6 speed manual w/ 3.21's and i wouldnt do it again....i believe id have been much happier w/ 3.73s in stock form.
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
Last edited by Drsekelsky; 12-17-2012 at 04:23 AM.
12-17-2012, 08:02 AM
#49
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ive got a 2 door, 6 speed manual w/ 3.21's and i wouldnt do it again....i believe id have been much happier w/ 3.73s in stock form.
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
I live in flat ass texas and unless im on the interstate (65+) i rarely can <properly> leverage 6th gear.
even at 75+ the jeep will not pull even a moderate hill in 6th w/out having to down shift to 5th.
I just raised the jeep 2 inches (via teraflex leveling/boost kit) and its made no impact (certainly no improvement).
any taller tire (than stock) and its only gonna get worse (fwiw, i have both 16 & 17 inch cast alum jeep wheels, w/ stock tires, they are effectively the same size w/ the tires that mopar put on 'em...the wheel size has no impact on the 6th gear speed issue...other than unsprung weight...but again no detectible difference)
12-18-2012, 07:02 PM
#50
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