SouthSideSteve

I've read all the gear threads, but I've seen very few actual reviews of this setup. I know everyone says 4.88s are the way to go, but looking at the numbers, the difference is only ~100rpms @ 70ish mph. I realize the mpg will suffer some, but i want to hear from people with this setup.




How are your rpms on the highway? and given the chance would you have gotten 4.88s?

Phishjeep

That's the way I'm going to go. Keeps the door open for 37s later, more accel around town, and mileage around town may even be a little better. On the interstate, keep it under 70-75 (which I need to do anyway), and it shouldn't be too big a deal.

RedrockX

ask Socalchuckster... he's running 5.13's with a stick and 35's.
I think he told me its "a little much", but check with him to see what he thinks now.
I'm going 4.88's with 35's (stick)

GadgetFreek

I did it as well. At first I thought it was a little much. At a corrected 70mph I am running right at 3000rpm. Most of my driving is less than 15mi one way if I run into town. Otherwise, I am making short (less than 5 miles round trip) to work or family/friends. I am seeing about 13mpg on average, but I know most of it is from my short blasts down the road. I also kinda drive it like I stole it most of the time so.......

I will say in 2wd in 1st gear i can let the clutch out and just crawl. It sometimes stutters a little but the rpm's are high enough that i can not kill it with no clutch and no gas (if that makes sense).

Glad I did it and don't regret not going 4.88. My decision was based solely on availability. I ordered 4.88 but they were in infinite backorder so I went with what I could get.

jkkat

With RubyDoo, 60 is about 2600 rpm, 65 is 2750 and 70 is about 2900 or 2950

brent_f70

I have 5.13's, 6 speed and 35's. I wouldn't swap to 4.88 if it was free and you gave me an extra $100 on top. 5.13's are perfect for 35's and if you have a Rubi......you can crawl over almost anything in 4 low.

Top end wise I have hit 94MPH and could have gone faster but I was not looking to test the Jeep or try my chances with the popo. The truck I was following decided to have fun on a straight a way so I just followed along and it did fine.

I average between 16.5 and 17MPG....in a 2 door

jmelgin

I currently have a stick w/ 3.21 gears & 35" tires. I'm contemplating regearing with either 4.10's, 4.56's, or 4.88's.

Bone stock, I was getting 19-20 mpg combined city/hwy driving but not overly enthusiastic with acceleration.

Since I've gotten the 35" tires, I've run a "test" by only using 1st thru 4th gears. At a true 70 mph in 4th gear, I'm turning 2800 rpm which is similar to what I'd see if I had 4.88's in 6th gear. Acceleration on the hwy in this range is OK. Got around 16-17 mpg.

I'm running another "test" now by using 1st thru 5th gear. On the hwy at 70 mph, I'm turning 2300 rpm which would be the mathematical equivalent of 3.95 gears (close enough for simulating 4.10's). Haven't finished a full tank of gas yet so can't speak to the mpg's but acceleration sux.

Any advice??

SouthSideSteve

don't waste your time/money swapping to 4.10s. Get 4.88s atleast imo. My decision was only between 4.88s and 5.13s, I will be having 4.88s installed next week. I wasn't comfortable with the rpms that 5.13s would provide, and 4.88s put me back to stock or very close to it. I just want to never have to use 1st gear on the street and have 6th gear back on the highway. From what I've read 4.88s will give me that.

JPop

I think jmelgin is going by things the right way and getting a feel for how his vehicle will drive after making the gear change. All too often these gear change threads are predicated in achieving more power when all they really do is change the rpm range someone may operate in.

IMO, you can't make an appropriate gear selection until you've completed what your going to do on the power plant side ie, CAI, headers, exhaust and programmer. If this was the case you wouldn't see so many people clamoring for 4.88s and 5.13s.

Steep gears certainly have their place on the trails and climbing, but they certainly don't do anything but change the rpm range on the daily drive or commute. Pulling out 30-40lbs of additional torque in the 15-2500 rpm range would certainly cause a lot of people to rethink their gearing needs, while serving their quest for performance, upgrading efficiency and increasing mpg.

Mssbbmia

In my experience with 3 different JKs and several combination's of 35 and 37 inch tires the 4:88 works best with 35s and the six speed trans. With an auto the final drive is over driven more and the 5:13 have an advantage. If you plan to run 37s with the stick or even think you might some day run the bigger tire, I would go with the 5:13. I also found that after 62-63mph the fuel mileage deteriorates quickly. The 3.8L van motor doesn't mind spinning fast compared to the old 4.0L inline six, so 3,000rpm sounds bad but its not really a problem on the 3.8L. IMO