Considering a future re-gear, need advice

Jeepster97TJ

Jeepster97TJ

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Nov 8, 2023
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Anderson, SC
I am a new Jeep TJ owner. I have wanted a Jeep for 20+ years. I was finally able to pick up a 97 with 78k on it and not a bit of rust anywhere. Long story short it came with like new 33" tires and eventually I will down size to 31" in the future. The axle says 3.07 and most likely it hasn't been changed, but I don't know for sure. I drive it daily and stay under 55 for the most part and 4th gear is where she runs. It doesn't seem to lack for power. I am going to try determine if it for sure is 3.07. Should I wait until I do a tire downsize before I re-gear? I've seen recommendations to run 4.56 with 33". Just not sure how important it is to re-gear. This is all new to me.

4.0L 5-speed
 
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My guess is you probably do have 3.07s, but it wouldn’t hurt to confirm.

If you’re going to run 31’s long term, my suggestion would be 4.56. That is a great combo for a 4.0 5-speed. So you could do 4.56 for the 33’s whenever and then downsize tires and it’ll still be great, better than it would be on the 33’s IMO. FWIW, I had 4.10 and 31’s for a while and while it was very good, I always wished for 4.56.
 
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machoheadgames said:
My guess is you probably do have 3.07s, but it wouldn’t hurt to confirm.

If you’re going to run 31’s long term, my suggestion would be 4.56. That is a great combo for a 4.0 5-speed. So you could do 4.56 for the 33’s whenever and then downsize tires and it’ll still be great, better than it would be on the 33’s IMO. FWIW, I had 4.10 and 31’s for a while and while it was very good, I always wished for 4.56.
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I will confirm the current gearing, but I really appreciate the confirmation on 4.56. I assume it is 3.07 because the tag is still on the rear end.
 
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Jeepster97TJ said:
I am a new Jeep TJ owner. I have wanted a Jeep for 20+ years. I was finally able to pick up a 97 with 78k on it and not a bit of rust anywhere. Long story short it came with like new 33" tires and eventually I will down size to 31" in the future. The axle says 3.07 and most likely it hasn't been changed, but I don't know for sure. I drive it daily and stay under 55 for the most part and 4th gear is where she runs. It doesn't seem to lack for power. I am going to try determine if it for sure is 3.07. Should I wait until I do a tire downsize before I re-gear? I've seen recommendations to run 4.56 with 33". Just not sure how important it is to re-gear. This is all new to me.

4.0L 5-speed
Click to expand...

Jeepster97TJ said:
I am a new Jeep TJ owner. I have wanted a Jeep for 20+ years. I was finally able to pick up a 97 with 78k on it and not a bit of rust anywhere. Long story short it came with like new 33" tires and eventually I will down size to 31" in the future. The axle says 3.07 and most likely it hasn't been changed, but I don't know for sure. I drive it daily and stay under 55 for the most part and 4th gear is where she runs. It doesn't seem to lack for power. I am going to try determine if it for sure is 3.07. Should I wait until I do a tire downsize before I re-gear? I've seen recommendations to run 4.56 with 33". Just not sure how important it is to re-gear. This is all new to me.

4.0L 5-speed
Click to expand...

Jeepster97TJ said:
I am a new Jeep TJ owner. I have wanted a Jeep for 20+ years. I was finally able to pick up a 97 with 78k on it and not a bit of rust anywhere. Long story short it came with like new 33" tires and eventually I will down size to 31" in the future. The axle says 3.07 and most likely it hasn't been changed, but I don't know for sure. I drive it daily and stay under 55 for the most part and 4th gear is where she runs. It doesn't seem to lack for power. I am going to try determine if it for sure is 3.07. Should I wait until I do a tire downsize before I re-gear? I've seen recommendations to run 4.56 with 33". Just not sure how important it is to re-gear. This is all new to me.

4.0L 5-speed
Click to expand...

This “before & after” data should confirm if your current gears are 3.07 & also what 4.56 gears will do for you. You just need an old portable GPS or maybe some kind of phone app that does the same thing. Freeway mile markers coming by at a mile per minute is also 60 mph.
Personally, If I were going with 31” tires I would use 4.10 gears, but that’s just me.
While the gears are being changes it’s a great time to also install chromoly axle shafts & either lockers or limited slips. Doing that at the same time will save a lot of labor costs.
Good luck!

IMG_8217.png
 
L J said:
If that's accurate, it can't possibly have 3.07s
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That’s an assumption. There are plenty of folks out there who have 3.07 and say it’s just fine. You or I would never say that, but we’ve driven other setups. He’s only going 55 and he’s leaving it in 4th. Chances are he has 3.07 and just hasn’t pushed it enough to realize the deficiencies. While 3.07 certainly sucks, it will still roll and to someone who is new at Jeep ownership, may not be that bad in their perspective.
 
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GregBelleville said:
Thanks, I'm wondering how much of a difference I'll notice going from 3.73 to 4.10?
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10% gear change roughly. It’s not going to go from a dog to amazing with one gear step. It will of course be an improvement.

I remember having this discussion with you in the past. You might need to do a few things, like check your cats for clogging, adjust the transmission bands, etc. There may be something making yours not drive so great - something more than just 3” larger tires. I would definitely recommend the regear but from how you describe yours driving, I wouldn’t expect a 10% regear to fix everything. That said, I wouldn’t regear extra deep to make up for it either. I like lower gears than most but I wouldn’t want 4.56 on 33’s permanently with the 3 speed.

Did you ever use GPS to verify your actual speed and what rpm you're at at each speed? How did you confirm you have 3.73?
 
GregBelleville said:
Jerry what would be your recommendation for the 32rh on 33s? I'm wavering between 4.10 or 4.56, not sure if 4.56 would be too deep for 33s and the 32rh?
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4.10 is how I'd go, 4.56 would definitely be too deep for 33's for the 32RH unless it's strictly an offroad Jeep.
 
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