3.73 & 29''... 4.10 &... 31.7''?

[AlexKJ]

29'' tall tires and 3.73:1 gears is one combination you found from factory... I assume that is a correct combination for both power and fuel economy...

As for an example, this combination throws 67mph at 2000rpm, considering 2WD position in the transfer (1:1) and the O/D of the 42RLE engaged (0.69:1).

I've always read here that you have to regear to 4.10 if you go for a 245/75R16 (OD: 30.5-30.7), but with these tires and 4.10, at 2000rpm you'll go slower: 64mph

Yeah, sure... 4.10 gears and 31'' tires certainly gives you more power off-road... but, as I see it, If you regear to 4:10 with 245/75R16 tires you'll end out of factory spec as well...

So... What tire's size need I to have for going back to factory spec after a 4.10 regear?

According mi calculations is an OD of 31.7, which is close to a 265/75R16...

What I get is that you *have* to regear a 4:10 with 32'' tires to go back to factory specs... but you have to make a compromise if you go for 31''... City economy and increased off-road performance (4.10) vs highway economy (3.73) maybe... Idk...

What do you think?

 

[tommudd]

You are right and wrong, it may seem the way you describe , but what you are not adding in is the extra weight of larger tires, skids, extra frontal area due to lift etc, all of that adds to what you have to roll down the road, so you need more power which you get by going to lower gears, even though it may appear that you are giving up 3 MPH you will actually gain through more power and increased fuel mileage

 

[AlexKJ]

That makes perfect sense...

Thanks!

 

[LibertyOrDeath]

Plug some numbers in here and see what you get.
Click Here

 

[kjweston]

hey i just put on 265/75's and i guess i need to regear. how do i go about doing so? and how much do you think it affects my mileage and power?

 

[jsc7002]

hey i just put on 265/75's and i guess i need to regear. how do i go about doing so? and how much do you think it affects my mileage and power?

it will help out a lot, but you are also looking at about $1100 to re-gear, its not easy or cheap. Ill find my parts list for you though.

 

[jsc7002]

Trailquest.com-call and ask for the 4.10 gears and re-build kit for the front axle of the Jeep Liberty
http://www.trailquest.com/axles/KJ_Model30.shtml

Gear Kit, Ring & Pinion D30A RATIO 4.10 $245.95 part# 5066085AA

Bearing, Inner Pinion, bearing & Cup $26.95 Replaces part # 4746979

Spacer, Crush $3.95 Replaces part # 5066047

Slinger, Pinion $2.95 Replaces part # 5066052

Seal, Pinion $10.95 Replaces part # 5066053

Bearing, Axle Shaft $10.95 Replaces part # 5066056 (2 parts)

Snap Ring $1.95 Replaces part # 5066064

Seal, Axle Shaft $6.95 Replaces part # 5066066 (2 parts)

Bearing, Outer Pinion, bearing & Cup $19.95 Replaces part # 8126499

Bearing, Differential Side, Includes bearing & Cup $29.95 Replaces part # 8126500


Motive 8.25 4.10 gears here for $168 and rebuild for $88
http://nationaldrivetrain.com/shopsite_sc/store/html/chrysler_825.html

 

[J-Thompson]

Trailquest.com-call and ask for the 4.10 gears and re-build kit for the front axle of the Jeep Liberty
http://www.trailquest.com/axles/KJ_Model30.shtml

Gear Kit, Ring & Pinion D30A RATIO 4.10 $245.95 part# 5066085AA

Bearing, Inner Pinion, bearing & Cup $26.95 Replaces part # 4746979

Spacer, Crush $3.95 Replaces part # 5066047

Slinger, Pinion $2.95 Replaces part # 5066052

Seal, Pinion $10.95 Replaces part # 5066053

Bearing, Axle Shaft $10.95 Replaces part # 5066056 (2 parts)

Snap Ring $1.95 Replaces part # 5066064

Seal, Axle Shaft $6.95 Replaces part # 5066066 (2 parts)

Bearing, Outer Pinion, bearing & Cup $19.95 Replaces part # 8126499

Bearing, Differential Side, Includes bearing & Cup $29.95 Replaces part # 8126500


Motive 8.25 4.10 gears here for $168 and rebuild for $88
http://nationaldrivetrain.com/shopsite_sc/store/html/chrysler_825.html

and dont for get to do the lockers while you are in there
so tack on another $1000 or so for starters ,that will get you a Detroit Locker rear and a Detroit True Track front
if it is worth doing then it is worth doing right