JayhawkJeep

It's a Jeep thing

BlackNorthernJK

all I can tell is you have an '08 2dr 6sp
you should have 3.73 gearing
even with my heavier '07 4dr, 3.21 gearing 6sp I never encountered a problem maintaining highway speeds in 6th...until I got my 33's on

spinlock

If you are running 3.21 gears I have felt your frustration. The performance of my stock was unacceptable for my taste.


IMO, the JK is obviously geared high with a strong bias towards fuel economy.

However, now even though I am running 35" tires, the 5.13 gears and the Flashpaq have changed the performance personality. I can sustain 80-85 MPH on the flat (albeit with minimum ability to accelerate at that speed). My JK will also maintain 70 MPH on all but the steepest inclines in OD.

With a 6 spd you have more flexibility, but even manual shifting has its limits.

jeepmedic

5.13s or a HEMI

ronjenx

Don't forget, 6th is overdrive. There is nothing wrong with keeping it in 5th, which is 1:1, whenever needed.

GoodysGotaCuda

Sounds like normal operation to me. Regear or add more cylinders

Dog Doc

Following this thread and this most likely is a stupid question...but I will ask anyway!
Is it hard on my jeep to run the rpm's around 3000rpm to keep up with the local traffic for a long period of time? That is 3.73's, auto, overdrive off with heavy 33" tires...

ronjenx

No. It can do it all day long. Like I said a few posts ago, nothing wrong with having the transmission in 1:1 if needed. That's why there is an O/D Off button.

tommy35SS

Check your owners manual and see what it days about running the automatic with overdrive off, first gear, and second gear. O/D off should be fine as 30 years ago virtually all cars had no overdrives except those that had a manually engaging O/D(separate switch for it, and you could engage it in any gear, usually on manual transmissions too), a lot had no lock up torque converter either. I know my Camaro owners manual(I don't own a JK yet) said something like it was fine to run with no overdrive on for as long as you want. In second and first it said don't run for over 25 miles in those gears

Anyways I put a auxiliary tranny cooler on it, fluid goes through the radiator cooler, then the auxiliary cooler mounted in front of the radiator. So I can run in those gears(1st and 2nd) all day long basically

tgsfire

Hey thanks guys for all the posts. Right now my jeep is pretty stock except for the wheels and tires, but they are not 33's yet(juat 265/70/17's). So I guess I will just keep doing what I am doing. Like I said its mainly going into the wind.
With time I will more than likely get diff. gearing.