Stock Rubicon gearing vs 33s with 4.56
- Thread starter Rut Row
- Start date
deadbeat son
TJ Addict
All I know is that after moving from a NV3550 with 31s and 4.56 gears to a 42RLE with 33s and 5.13s, I’m ready for an AX-15 swap and a switch to 4.88s. 
The one that met their costs, mileage, government reqs, for most of the people, most of the time, for a particular Jeep model they were building that year. Different between models and years. My point is the same as yours, there isn't an ideal.
I would agree that all were ideal for Chrysler when they sold them (profit$), and almost none are ideal for we owners.
Of course. That's why we change them. And discuss, and argue, about the ideal ratio.
If you don't stand for anything, then you stand for nothing.
I’ve driven a 4 cyl 5 speed that had 31’s and 4.88’s and it held up pretty damn well (except on the turnpike that was rough). So a rubicon on 4.56 gears and 33’s sounds almost perfect.
I had 33 inch tires on beadlock rims with 4:56 gears and the NV 3550- It was fantastic.
Would I do 4:88 with that? Likely, if there was a hint I would go up to a bigger tire.
I'm running the NV3550 / 231 / 33s and just installed 4.88s. My tires are probably really 32s because I am pushing just a hair under 3000 RPM at 70 MPH on flat highway. Most of my driving around here is up and down mountains and 60 MPH so it is just perfect most days. Also gives me a bit of gearing room when/if I move to larger tires later on. Don't regret it at all.
I think I’ve said this before here, but:
I don’t think I’ve EVER heard someone complain about having overgeared. Maybe once or twice. The opposite however we hear all the time.
It winds up like this because we're lazy and lacking information.
It would be possible to dyno a jeep with different tire combos and find out what power it takes to maintain different speeds. Adding correction factors for altitude and grade are also possible.
Dyno a given motor and find the most fuel efficient rpm for the required power outputs from above.not hard with fuel injection keeping track of fuel consumption for us. Or focus on staying in the power band for a faster jeep.
Then you do the math and gear according to your tire size,trans and speeds.
It changes depending on tire size and drag of course. Maybe some day an engineering student can do months worth of work for us and make a spread sheet?
.... Maybe some day an engineering student can do months worth of work for us and make a spread sheet?
They are too lazy to do any of that.
They are too lazy to do any of that.
In the mean time its easy to just not gear like you have a big block pickup and a granny trans.a lot of the shitty gear recommendations come from non overdrive guys and get carried forward by the rest of us.
Even the cj community is starting to recognise there are a few gear steps between one and the other. Probably 3-4 gear steps with a 42rle
I got a couple engineering major buddies, but none that are that invested into Jeeps
It’d be interesting to experience an overgeared TJ. Something like 5.38s on a 32RH and 31s.
We have that to some degree by treating the 42rle as a 3 speed and ignoring the OD. Which means many of us know what a 32rh is like when geared to 5.38 and pushing 35s.
42rle/33.875"/5.38=4002rpm @ 75mph in 3rd gear
32rh/33.875"/5.38=4002rpm @ 75mph
The 32rh needs to be geared to 3.73 to closely match the OD of the 42rle. This is udergeared for both, as evidenced by the factory gearing of the 32rh.
42rle/33.875"/5.38=2762rpm @ 75mph
32rh/33.875"/3.73=2775rpm @ 75mph
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I got a couple engineering major buddies, but none that are that invested into Jeeps
It’d be interesting to experience an overgeared TJ. Something like 5.38s on a 32RH and 31s.
Hunting camp jeep. And a pretty sweet one at that. I'd have no issue replacing my dads 3.73s with 5.13s in his 32rh/3.73/245/75r16
98 sahara. He would drive it like the flat fender he wanted me to get him in the first place.
Cruising town and logging roads with ease. No need to gun it anywhere with the torque available
Hold up, so a 32RH is just a 42RLE w/OD off. Very interesting.
I’ve driven a 32RH TJ w/ the same gearing/tires as I have now, and the driving experience felt different somehow.
Hold up, so a 32RH is just a 42RLE w/OD off. Very interesting.
I’ve driven a 32RH TJ w/ the same gearing/tires as I have now, and the driving experience felt different somehow.
They are not the same; but simulating 42RLE 3rd with 32RH 3rd is equivalent since both are 1:1.