Re-gearing

[jjvw]

I didn't say it wouldn't run. You'll only have an issue if the shaft has any imbalance on the top end as it's tough to find a shop that can spin one that fast to address it. To your point, higher speeds, higher angles, everything we do is tougher on the driveshafts and pretty much everything else on the jeep.

Gears are a personal choice and there isn't one right answer. For me, I'd rather the engine rpm be a bit lower if it's still in a range that will perform. I knew my jeep well before deciding to do the gears and the specific problem I wanted to address. It wasn't having a problem holding the speed limit on 4.10s most of the time. The RPM was too low in 4th to make the power I needed to hold the speed limit in a specific place I travel. The 4.56 and 4.88 ratios both brought the rpm back up where I knew it would make enough power. I also looked at the highway cruising rpm at 70, 80 and 85mph which are the speed limits in the states I live in and surrounding and decided the 4.88 ratio would have me at a higher engine rpm than I'd want to be at. Everybody's choices can be different. I'd question the sanity of someone staying on 3.07s with 35s, but if they like being a rolling roadblock, cool.

It's not some magic math. The later JK/JL Rubi owners seem to be totally fine on 4.10s with 33s and many are happy with 35s because the engines produce more power. Most of the LJR 6 speed owners on 33s don't seem to feel the need to change out from the 4.10s because the gear ratio options are better in the NSG370 (unless they crap out). Everyone says the 4.0L is great for low end torque. Obviously it's underpowered.

The argument of gears being a personal choice is a bit of a dishonest assertion of autonomy when we know full well that most never get to experience anything other than the single choice they made, a choice often made based on a collective hive mind of people having done exactly the same thing. This is where the bullshit justification of "it's a Jeep thing" comes from as an excuse for accepting lackluster performance. Because it is a Jeep.

Meanwhile, some of us have a broader range of experiences that somehow consistently point to a similar conclusion that deeper gearing and higher rpms results in a nicer driving experience. And these consistent similar conclusions create a framework that can be applied across the board to multiple combinations of tire, transmission and gear. With very few caveats, none of that results in numerically lower gears when higher is available.

 

[5.3L 98 TJ]

Agreed ... 4.88 for 5 spd with a 4 cylinder with 33s

I had this set up before I LS Swapped

Call east coast gear supply. Those guys are awesome and will talk you through every bit of the drivetrain.

Just know that you will be speed limited with this. 72 will be about as fast as you can go. Dont ask me how I know...

Make sure the plugs are correct ie still have service life and

 

[ffcol]

I had 4.11's and had a worn out pinion gear. I decided to go to 4.56 (33" tires and NV3550) since I was paying for half a gear change anyways. Thought about 4.88 but decided not to as I am sticking with 33" tires and do take it on the highway. Today was the first long highway trip since the gear change. Was doing 80 mph to keep up with traffic. Had to go into 4th on some hills but it accelerated noticably better at highway speeds than the 4.11. I think I would have been happy with 4.88 and would probably go that route if I were to do it over, but I will pay attention to the 4.0 bolt on thread to see if anything is worth it to get some more HP in that sub 3000 RPM range which would help immensely.

 

[hear]

I had 4.11's and had a worn out pinion gear. I decided to go to 4.56 (33" tires and NV3550) since I was paying for half a gear change anyways. Thought about 4.88 but decided not to as I am sticking with 33" tires and do take it on the highway. Today was the first long highway trip since the gear change. Was doing 80 mph to keep up with traffic. Had to go into 4th on some hills but it accelerated noticably better at highway speeds than the 4.11. I think I would have been happy with 4.88 and would probably go that route if I were to do it over, but I will pay attention to the 4.0 bolt on thread to see if anything is worth it to get some more HP in that sub 3000 RPM range which would help immensely.

I have the same nv3550/4.56 on 33’s, and it’s so great…if 4.88 is actually better then I can’t even comprehend it. But there is always the theoretical possibility that anything *could* be better, but I’m probably never going to know. Because for the most part we live with what we have, to a previous poster’s point.

 

[jjvw]

I have the same nv3550/4.56 on 33’s, and it’s so great…if 4.88 is actually better then I can’t even comprehend it. But it could be better, and I’m probably never going to know. Because for the most part we live with what we have, to a previous poster’s point.

488 would have been better.

 

[jjvw]

I had 4.11's and had a worn out pinion gear. I decided to go to 4.56 (33" tires and NV3550) since I was paying for half a gear change anyways. Thought about 4.88 but decided not to as I am sticking with 33" tires and do take it on the highway. Today was the first long highway trip since the gear change. Was doing 80 mph to keep up with traffic. Had to go into 4th on some hills but it accelerated noticably better at highway speeds than the 4.11. I think I would have been happy with 4.88 and would probably go that route if I were to do it over, but I will pay attention to the 4.0 bolt on thread to see if anything is worth it to get some more HP in that sub 3000 RPM range which would help immensely.

488 would have been better.

 

[NashvilleTJ]

I had 4.11's and had a worn out pinion gear. I decided to go to 4.56 (33" tires and NV3550) since I was paying for half a gear change anyways. Thought about 4.88 but decided not to as I am sticking with 33" tires and do take it on the highway. Today was the first long highway trip since the gear change. Was doing 80 mph to keep up with traffic. Had to go into 4th on some hills but it accelerated noticably better at highway speeds than the 4.11. I think I would have been happy with 4.88 and would probably go that route if I were to do it over, but I will pay attention to the 4.0 bolt on thread to see if anything is worth it to get some more HP in that sub 3000 RPM range which would help immensely.

The only bolt on which would make enough difference would be a supercharger.

Edit:



Yes, gallery, I know you can technically bolt on a turbo kit - but it seems like a lot more work for less cool...