Changing diff ratio on 3.7L Liberty 2002 model

[African Child]

Need some help here? I would like to get my RPM a bit higher in top gear. It seems my Jeep got a 3.73 ratio. If I understand correctly a 4.10 ratio would increase the RPM? If this is correct, would the 4.10 gears from the 2.4L fit?

 

[profdlp]

Lots of people here have used the 4.10 from the 2.4L. I'm not an expert, but I'd bet someone who has "been there, done that" will be along to give you some step-by-step advice.

(welcome)

 

[TwoBobsKJ]

Yep, TomMudd has it figured out so it's pretty easy. He and I swapped in the front differential and rear axle from a 2.4L 4 cylinder into mine so I now have 4.10's. Given the tire size I moved up to my RPM's are basically back to stock.

Bob

 

[tommudd]

Need some help here? I would like to get my RPM a bit higher in top gear. It seems my Jeep got a 3.73 ratio. If I understand correctly a 4.10 ratio would increase the RPM? If this is correct, would the 4.10 gears from the 2.4L fit?

Are you running larger tires? Lifted?
If so then yes going to 4.10s works great for sure , even when going to a tire an inch to one and a half inch taller

 

[African Child]

Thanks for the reply! This is wonderful news, so just to clarify before I run off to the local scrap yard, the internals of a 2.4L will fit straight in my 3.7L differentials? It will make life so much easier on my next trip to the Kalahari with a better ratio.

 

[tommudd]

Thanks for the reply! This is wonderful news, so just to clarify before I run off to the local scrap yard, the internals of a 2.4L will fit straight in my 3.7L differentials? It will make life so much easier on my next trip to the Kalahari with a better ratio.

Just swap the complete rear and front diff , no need to pull them apart and redo , swap everything. Just make sure what ratio it is before buying them

 

[African Child]

Thanks again for all the info, will keep you up to date with the project. First thing now to locate a old 2.4L This was not a very popular model in South Africa but I think I know where to find one.

 

[blue_kjR417]

I'm in the process of doing this very thing, I was able to source a local front axle assembly from an 04 2.4L through a local salvage yard. I had to order the rear axle assembly online from a salvage parts website its from a similar 2003 2.4L model. Both came factory with the 4.10 ratios and I spent $428 after sales taxes on the front and $437 on the rear after shipping. Not bad considering the parts kits to rebuild my current axles were in the $850 range from JBAoffroad.com and I was estimated another $600 for a technician to install them for me. The local dealership has assured me they can flash my KJ's computer for the new gear ratio and tire size and the charge is one hour of diagnostic fees they said roughly $108. Not too bad to come out with about the same in parts and the flashing is required for both ways of axle swaps or regearing your current axles but this way I can save the $600 labor by swapping them out myself. I plan to do a detailed how to explaining some of the key things I've learned from researching and from our resident expert on pretty much all things KJ tommudd.

 

[African Child]

I found a set but the rear diff have disc brakes on and mine drums. What is the implications of this? How difficult would it be to adapt the rear disk brake setup to mine.