Another gear thread
07-31-2015, 04:27 AM
#11
JK Jedi
Is the consensus 4:88's with 37's? I have 35's with 4:10's and have been completely satisfied... moving up to 37's and I ordered 4:88's but was thinking I should drop down to 4:56's. Anyone with real world experience on both?
07-31-2015, 05:04 AM
#12
JK Freak
Join Date: Aug 2007
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Manual or Automatic trans? Recommendation for 37's with A/T is 4.88's. That would put performance right back close to stock with 4.10s and 32's. Manual trans you could probably get away with 4.56's on 37's, but if it were me, I'd stick with what you ordered. Granted, I don't have a 3.6L in my Jeep so my advice comes simply from what I've read regarding the 2012+ with the 3.6L and 5-speed auto. But if even Northridge is saying 4.88's for 37's.....you can be pretty certain that's where the Jeep is going to be happiest.
07-31-2015, 06:22 AM
#14
JK Junkie
I ran 4.88s with 37s and manual trans. Wouldn't recommend it for a highway driver, especially if you like to cruise over 70. Awesome around town and on trails though.
Side note, my gas mileage stayed the same moving from 3.73/35s to 4.88/37s. Just goes to show that proper gearing makes for better efficiency.
Side note, my gas mileage stayed the same moving from 3.73/35s to 4.88/37s. Just goes to show that proper gearing makes for better efficiency.
07-31-2015, 06:25 AM
#15
JK Junkie
Oops, meant to add that I had the 4.88s for a couple days with my 35s. Way too much gear. I'd never recommend that combination to anyone who exceeds 55 mph on a regular basis. Offroad, you won't notice a difference between 4.56 and 4.88. I see no reason to run 4.88 on 35s. Just my opinion.
With 37s I was around 2850 rpm at 70. An auto should be higher. With 35s you are over 3000 rpm. Most driveshafts are not rated to spin that fast at normal operating load. Probably ok with the stock shaft, but will likely encounter issues with an aftermarket.
With 37s I was around 2850 rpm at 70. An auto should be higher. With 35s you are over 3000 rpm. Most driveshafts are not rated to spin that fast at normal operating load. Probably ok with the stock shaft, but will likely encounter issues with an aftermarket.
07-31-2015, 06:37 AM
#16
JK Super Freak
3.6 manual with 488s and I feel it's perfect for 37s
07-31-2015, 11:43 AM
#17
JK Newbie
Join Date: Jan 2014
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By the way, I have an AT. I noticed a definite increase in torque at low speeds, of course, but the RPMs are high at highway speeds. MPG was about the same but I don't do a lot of highway driving. 4.88 would have just been too much gear on the highway for anyone who does highway miles. I'm running Fierce 35s, which are on the small side of 35.
08-01-2015, 06:55 AM
#19
JK Junkie
I've been running 4.56's in a manual jku with 35's and now 37's for a couple years. Normally I will drive my jeep about 800 miles round trip mostly highway once a month. I've driven it 5000 miles round trip to Moab and back. The closest legal wheeling that isn't a dirt road is about 120 miles away. I average about 15mpg highway driving through the Adirondacks to Canada averaging about 72mph at about 2500rpm. This is with a wheel and tire combo that has been 110lbs when I had toyo's and now is about 120lbs with cooper stt's on beadlocks. I have to down shift in the mountains and don't think I would if I had 4.88's. But my rpms on flat sections of highway would be around 2800. For my needs 4.56's have been perfect for 37's.
08-02-2015, 05:28 AM
#20
JK Jedi
Bump... anyone else with 37's and 3.6 with AT have any real world experience? Just want to be certain before I upgrade to 4:88's. Again, I'm not concerned about gas mileage... just looking for best all around driving...