New gear ratios ?

jeepmedic · **Posted:** Sat Mar 22, 2008 2:40 pm

Can anyone help out with suggestions?

I have the 04 Libby sport, with 245/75/16 tires. 3.7L motor with the stock auto tranny. 35K on it. Gas mileage is crap 13-16mpg.

I know the winter gas is somewhat at fault, and I am not happy with the small power loss in acceleration and the lack of acceleration while driving up large paved roads.

Any help/ideas with new gearing to help out with this ?

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

You can go to 4.10's to help with the power and acceleration. There are other things you can do to get more power to the ground, but it depends on how far you really want to go. As far as the gas milage is concerned, you're kind of out of luck. At least it's about time for the winter mix gas to go away, and you won't need to let it warm up so long.

jason thompson · **Posted:** Sat Mar 22, 2008 9:04 pm

if you put 4.10's in it you will get some of your MPG back but not enough to cover the cost of 4.10's just for the sake of MPG
now if you also do it for better power ect then it is up to you if it is worth it or not
if you feel it lacks in low gear as far as trails go then you can do a 4 to 1 in the np231 T-case ,if you have it
you will need to get a DS built but still IMO well worth it

Jeepjeepster · **Posted:** Sat Mar 22, 2008 10:52 pm

4:10 gears will bring the pep back and the mpg back up around town and at lower hw speeds.

It may take the mpg down at higher hw speeds though.

Do you have good spark plugs and a clean air filter? It warmed up a little and I cleaned my K&N this past week. I got 16mpg on the last tank(before it warmed up and before air filter cleaning) but my evic has said 19-20 on this last tank. Ill figure it by hand when I fill up but Im hoping this warm weather and a nice clean air filter has brought it up a couple.

dieselenthusiast · **Posted:** Sun Mar 23, 2008 2:10 am

jeepmedic wrote:

Can anyone help out with suggestions?

I have the 04 Libby sport, with 245/75/16 tires. 3.7L motor with the stock auto tranny. 35K on it. Gas mileage is crap 13-16mpg.

I know the winter gas is somewhat at fault, and I am not happy with the small power loss in acceleration and the lack of acceleration while driving up large paved roads.

Any help/ideas with new gearing to help out with this ?

Honestly, it might be as cost effective to buy a second vehicle, (like a car that gets 40 mpg) then to worry about increasing fuel economy in your Jeep. You have steel wheels, bigger tires, and a lift, what can you expect? Depending on how much you drive, a second car as a daily driver might be worth it.

KJ04 · **Posted:** Sun Mar 23, 2008 9:22 am

With warmer weather just around the corner, we'll all start seeing an increase in mpg. Hang in there for awhile longer. :lol:

Guest · **Posted:** Sun Mar 23, 2008 11:46 am

Have you had your speedo recalibrated? you have to remember the mileage you're calculating now is NOT accurate, and if you have an EVIC, it's not either. since the 245/75s, my KJ tells me I'm getting much worse gas mileage, but my driving habits haven't changed, and I'm not putting any more gas in it than I did before.

dieselenthusiast · **Posted:** Sun Mar 23, 2008 12:03 pm

ThunderbirdJunkie wrote:

Have you had your speedo recalibrated? you have to remember the mileage you're calculating now is NOT accurate, and if you have an EVIC, it's not either. since the 245/75s, my KJ tells me I'm getting much worse gas mileage, but my driving habits haven't changed, and I'm not putting any more gas in it than I did before.

Good point, can the dealership recalibrate for us?

Guest · **Posted:** Sun Mar 23, 2008 12:05 pm

Yep, and at least for me locally, they're the cheapest. They reprogram the computer, and the other speedometer shops around me just put some kinda electronic device in between the sensor in the rearend and the computer to trick the computer...Stealership would be the way to go.

06LIB · **Posted:** Sun Mar 23, 2008 1:07 pm

I regeared to 4.56 and gas milage still sucks, but I can hang with a stang now :twisted:

.......I have had 3 different dealerships try to calibrate the speedo and none have got it right, so MAKE SURE the dealership knows what you are lookig for and get in writing that they will refund your money before they start....the first 2 dealers that I paid to do it just simply said they will try again but will not refund my money, so they both tryed again and again to no evail....the 3rd refunded my money after I b*tched enough.....sooooo my speedo is still off....by alot......but it shows Im going slowwer than I actually am so I guess my warranty will last longer, so I ll have somebody who knows what they are doing fix it after the odo shows im out of warranty :twisted:

renegadekj · **Posted:** Sun Mar 23, 2008 10:07 pm

06LIB.
Where did you find 4.56 gears for the kj????? I've been looking for them for a while now! Who makes them??

Thanks

Josh

dieselenthusiast · **Posted:** Sun Mar 23, 2008 10:13 pm

renegadekj wrote:

06LIB.
Where did you find 4.56 gears for the kj????? I've been looking for them for a while now! Who makes them??
Thanks
Josh

I don't think anyone makes 4.56 gears for the KJ. :wink:

That would be cool if they did!

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

The tire rotation per mile settings are kind of strange in the Libby. Mine was factory set at 766. The setting of 682 was way off for my 245/75R16 SA's also. I had the tech from the dealership go for a ride with me at 60 mph according to the speedo, compared that to the GPS, did a little math, and ended up setting it at 714. It's within 0.5 mph at 60 mph now.

I think 06Lib must be driving a 4X2. There are 4.56 gears for the 8.25 in the rear, but as far as I know the 4.10's are as far as you can go with the Dana 30A.

tjkj2002 · **Posted:** Sun Mar 23, 2008 10:28 pm

dieselenthusiast wrote:

renegadekj wrote:

06LIB.
Where did you find 4.56 gears for the kj????? I've been looking for them for a while now! Who makes them??
Thanks
Josh

I don't think anyone makes 4.56 gears for the KJ. :wink:

That would be cool if they did!

When your only 2wd you can go to 4.56's,they make them for the 8.25 rear diff.

dieselenthusiast · **Posted:** Sun Mar 23, 2008 11:27 pm

tjkj2002 wrote:

dieselenthusiast wrote:

renegadekj wrote:

06LIB.
Where did you find 4.56 gears for the kj????? I've been looking for them for a while now! Who makes them??
Thanks
Josh

I don't think anyone makes 4.56 gears for the KJ. :wink:

That would be cool if they did!

When your only 2wd you can go to 4.56's,they make them for the 8.25 rear diff.

Makes sense, I didn't think they had them available for the 4x4. I will have to settle for 4:10's

jeepmedic · **Posted:** Mon Mar 24, 2008 11:13 am

Thanks for all the adivse. I am not so concerned about the mpg's, as I know for what I want with my libby I just have to deal with it. The area I live in is really hilly and she's just a dog up the big hills, and has lost some of the guts she used to have. I just what the libbys balls back !

I prob need to check the plugs, and I have a new clean KN filter.

dieselenthusiast · **Posted:** Mon Mar 24, 2008 11:26 am

jeepmedic wrote:

Thanks for all the adivse. I am not so concerned about the mpg's, as I know for what I want with my libby I just have to deal with it. The area I live in is really hilly and she's just a dog up the big hills, and has lost some of the guts she used to have. I just what the libbys balls back !

I prob need to check the plugs, and I have a new clean KN filter.

Yep, like everyone has already stated, 4:10's might be your ticket for bigger testicles.

BeepBeepJeepJeep · **Posted:** Mon Mar 24, 2008 2:22 pm

dieselenthusiast wrote:

jeepmedic wrote:

Thanks for all the adivse. I am not so concerned about the mpg's, as I know for what I want with my libby I just have to deal with it. The area I live in is really hilly and she's just a dog up the big hills, and has lost some of the guts she used to have. I just what the libbys balls back !

I prob need to check the plugs, and I have a new clean KN filter.

Yep, like everyone has already stated, 4:10's might be your ticket for bigger testicles.

Actually, probably, you're only reasonable ticket.

I still need to get 4.10s into mine, but I do plenty of highway driving so I'm not sure if I should or not ahhhh...

dieselenthusiast · **Posted:** Mon Mar 24, 2008 2:38 pm

BeepBeepJeepJeep wrote:

I still need to get 4.10s into mine, but I do plenty of highway driving so I'm not sure if I should or not ahhhh...

At what highway speed do you think 4:10's with 31" tires are no longer advantageous?

Blue Wrench · **Posted:** Mon Mar 24, 2008 2:40 pm

dieselenthusiast wrote:

renegadekj wrote:

06LIB.
Where did you find 4.56 gears for the kj????? I've been looking for them for a while now! Who makes them??
Thanks
Josh

I don't think anyone makes 4.56 gears for the KJ. :wink:

That would be cool if they did!

RRO says that their supplier US GEAR has 4.56's for front and rear. I ordered a set and they sent me a set up for a Zuki and I am currently awaiting re-ship for the libby gears. I will let you know IF they ever show up considering I have had nothing but trouble getting anything right from those guys.

New gear ratios ?

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