Upgrading gears
- Thread starter kimjeep
- Start date
wow that is such a great deal of expiation and thank you so much for taking the time. I know I barely ever go over 75mph with my Jeep, it just scares me. My Jeep has high mileage so it makes me nervous with going too fast. I just feel I won't have en ought time to do the 500 miles after the gears are installed for them to order new gears. But I am happy to hear from you about 4.56 will not be a lost cause. you don't think it being my daily driver with high mileage 260k miles will put too much stress on it?
5.13 benefits the Jeep at every gear at every speed. That gearing puts less stress on the entire drivetrain because it increases the mechanical advantage in favor of the engine, transmision and axles. Those components do not have to work as hard to turn the tires. There is no downside.
You already know this if you have ridden a multi speed bicycle where you are the engine.
4.56 would be better then you current gearing. But not as good as 5.13 would be.
I'm in a somewhat similar position to you right now since I am about to do a F/R Rubicon 44 swap with bigger gears, so I know how you feel right now. My best advice is to STOP AND RESEARCH. It sounds like you ordered through a shop so I would tell them to cancel and wait if you can. Just a couple of months ago I didn't know my gear ratio, the name of my transmission, or even what regearing was exactly, but through reading the countless threads on this forum about the subject I learned SO MUCH. It only took me about a day of research to learn enough to make the purchase I did, so I highly recommend you slow down a little and truly think this over.
You seem to want to keep this Jeep for a very long time as your daily, so its best to make the right choice now rather than fix it in the future. As far as stress on the engine is concerned, I can't speak too much on it. The 4.0 is tough as nails and enjoys higher RPM, that's what I have learned and it is easy to feel when you let it get there. Your transmission won't like hunting for gears though, which based on what @GoldenGorilla said, it most likely will be doing especially in the mountains.
Read up, understand what you have in your Jeep and what you're putting into it, and listen to the people here. They aren't making the recommendations they are for no reason.
You seem to want to keep this Jeep for a very long time as your daily, so its best to make the right choice now rather than fix it in the future. As far as stress on the engine is concerned, I can't speak too much on it. The 4.0 is tough as nails and enjoys higher RPM, that's what I have learned and it is easy to feel when you let it get there. Your transmission won't like hunting for gears though, which based on what @GoldenGorilla said, it most likely will be doing especially in the mountains.
Read up, understand what you have in your Jeep and what you're putting into it, and listen to the people here. They aren't making the recommendations they are for no reason.
Jeep told us a bit about what the 4.0 can do when they rolled the early TJs off the assembly line with the 3 speed automatic, 30" tires, and 3.73 gears running far higher rpms than what I have been advocating for many many years.
32rh/29.5"/3.73=3186rpm @75mph
Jeep was OK with that, but we have almost 30 years of people clutching their pearls over what they imagine are high rpms.
Last edited:
KennethS
TJ Addict
It's all the passenger cars trying to increase economy with overdrive transmissions and lower RPM. People have become afraid of turning over 2000 RPM on the highway. I see it all the time on the classic car forums.
I fully agree, that's why I'm fine with running the combo that I'll have for a while. I was mostly thinking in the context that she seems to want to daily it for another 15+ years and personally don't know enough about how high milage 4.0s act to speak in certainties. I can't see running near the factory rpm causing any issues though.
I'm the guy who bought mine 10 years ago at 56,000 miles and last year put a supercharger on it at 195,000 miles.
Superchargers are sooooooo cute!!!
(Sorry Josh - couldn't resist. You know I loved mine.)
thank you all for your input and will definitely take your advice. I am going to wait and see if they can return the 4.56 and they can order me the 5.13. plus, look into getting a 2in lift before the trip.. Thanks again everyone. This is why I look to the experts like all of you!
A stock Dana 35 isn't a good choice for a locker. It should be upgraded with bigger axleshafts and a matching locker. Aka super 35 kit.
So your choices if set on a rear locker really are-
Super35 and locker
Dana 44 and locker
If you don't you could end up like me...needing a trailer in a very inconvenient place!
Oh no! That would be my fear. Want to make sure I have it when I need it. Hope fully it is ok now?
The problem with and one of the many reasons I despise the 4.0 is no one can predict anything about them. I see them die a terrible death at sub 100,000 miles, others like my 2004 run circles around most in stock form with over 200,000 on it. The only thing less predictable is the 42RLE. Some last, some don't, there is no rhyme or reason to point to why.
Trying to pick and choose certain mods to guarantee longevity is a fool's errand.
I have been soul owner of my Jeep. She has done very good for me, my Jeep has over 260k miles on currently, and it is running strong. so hopefully she will be last another 15 years for me. I know maintenance and oil changes have been the most important.
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