What gear ratio should I install in my Jeep Wrangler TJ / LJ? (and other re-gearing FAQs)

[ShinyTravisto]

This thread has me now planning the next wallet lightening mission to be re-gearing. Been running 4:88's w/ 35's, rubicon axles, and everyone's favorite transmission (42RLE). Always feels like it wants to be in the wrong gear on my climb into the mountains towards home, climbing 4,000' over 18 miles.

 

[TexasTJ2004]

This thread has me now planning the next wallet lightening mission to be re-gearing. Been running 4:88's w/ 35's, rubicon axles, and everyone's favorite transmission (42RLE). Always feels like it wants to be in the wrong gear on my climb into the mountains towards home, climbing 4,000' over 18 miles.

It is always in the wrong gear because it is simply not geared right. 4.88 with 35s - it is correct gearing for 31s

 

[jjvw]

This thread has me now planning the next wallet lightening mission to be re-gearing. Been running 4:88's w/ 35's, rubicon axles, and everyone's favorite transmission (42RLE). Always feels like it wants to be in the wrong gear on my climb into the mountains towards home, climbing 4,000' over 18 miles.

I was running 488 for a while with the same setup. There was never a time when I thought that was enough gear.

 

[L J]

This thread has me now planning the next wallet lightening mission to be re-gearing. Been running 4:88's w/ 35's, rubicon axles, and everyone's favorite transmission (42RLE). Always feels like it wants to be in the wrong gear on my climb into the mountains towards home, climbing 4,000' over 18 miles.

Living in the SBNF 5.38 is the lowest gear (numerically) I'd consider. I'd also get in touch with mrblaine to send a Dorman pan to him and get a bung brazed(?) on, get one of his cooler fittings (if available), get a temp gauge and buy a Setrab cooler.

 

[mrblaine]

I was running 488 for a while with the same setup. There was never a time when I thought that was enough gear.

The 04 TJ Unlimited had 3.73 and stock tires with the supercharger. I bolted on JK 32's and regeared to 4.88 because of how much giddy-up I lost. I can't even imagine how much that would suck on 35's.

 

[ShinyTravisto]

Living in the SBNF 5.38 is the lowest gear (numerically) I'd consider. I'd also get in touch with mrblaine to send a Dorman pan to him and get a bung brazed(?) on, get one of his cooler fittings (if available), get a temp gauge and buy a Setrab cooler.

Did that this summer actually, well with a Derale cooler that Jerry has a write up for. Don't know the effects since I added a trans temp gauge at the same time, so no idea what it was before that. I'm assuming toasty from how bad the fluid smelled when I drained it. It's had 4:88's since I bought it. Consistent with all the other mods it came with that are almost, but not correctly done.

 

[bty34]

Anyone running 4.56 or 4.88 with a 4.0 and NV3550 on 35s? Feedback on real world driving please. No offense to anyone but I don't really care much about gear ratio charts and graphs as much as I care about the real world driving experience feedback from actual Jeep owners running this combo. Thank you!

I had 4.88 with that combo and switched to 5.38 while keeping 35s.

 

[TexasTJ2004]

Living in the SBNF 5.38 is the lowest gear (numerically) I'd consider. I'd also get in touch with mrblaine to send a Dorman pan to him and get a bung brazed(?) on, get one of his cooler fittings (if available), get a temp gauge and buy a Setrab cooler.

If you have LJ, then you can read transmission temperature from OBD. You dont have to use a bung and add thermal sensor into it. I had to do it because I have TJ 2004 which (similar to 2003) has separate TCM and transmission temperature is not readable through OBD. 2005 and 2006 have TCM integrated into TCM, so all the data is available in OBD.

 

[L J]

If you have LJ, then you can read transmission temperature from OBD. You dont have to use a bung and add thermal sensor into it. I had to do it because I have TJ 2004 which (similar to 2003) has separate TCM and transmission temperature is not readable through OBD. 2005 and 2006 have TCM integrated into TCM, so all the data is available in OBD.

I don't have an auto but if/when I do I wouldn't be interested in a dongle and an app on a phone when I could just glance at a gauge and get the info.

 

[MikeE024]

Don't forget it's propensity to over heat when off roading. But yes 0.69:1 overdrive ratio is a touch too high for the power plants Jeep used in the TJs with stock gearing.

In my experience, the propensity to overheat is in stop-and-go traffic and when pushing it on the highway. Wheeling in 4 low keeps the 42RLE running much cooler than the aforementioned scenarios.

 

[reddvltj]

In my experience, the propensity to overheat is in stop-and-go traffic and when pushing it on the highway. Wheeling in 4 low keeps the 42RLE running much cooler than the aforementioned scenarios.

The tendency to overheat comes from running with the torque converter out of lock up. Whether you are in low range or high does make a difference but not enough to avoid needing an auxiliary cooler.

 

[MikeE024]

The tendency to overheat comes from running with the torque converter out of lock up. Whether you are in low range or high does make a difference but not enough to avoid needing an auxiliary cooler.

I didn't say anything about not needing a cooler.

 

[Hasselblad]

Oh FFS, now the 5.13 that the installer was going to put in (Revolution) are on backorder everywhere, and the appointment is set for next week.

 

[MikeE024]

Oh FFS, now the 5.13 that the installer was going to put in (Revolution) are on backorder everywhere, and the appointment is set for next week.

That's not bad news if Revolution has 5.38s and you plan to run 33s+. I would run 33s with my 5.38s without any worries.

 

[MikeE024]

Did wonders on my 06. Since it doesn't have the mechanical kickdown, the tuner solved that as well. Being able to tromp the pedal to get out of the lug is wonderful.

I don't know what "tromp" means in this scenario, but if you have to stomp it to kick it back down to 3 when going less than 45+mpg, your 4-3 kickdown isn't programmed as high as it probably should be (or you have something else weird going on). A gradual push of the throttle downshifts mine out of OD when cruising up to about 40mph or so, and the "pedal push" and "downshift" process is very smooth and natural. This is the case until I'm up around 50mph+ in OD (since I don't want it to kickdown at highway speeds).

That said, it's best to get your gearing in order, then dial in the shift points if you have an 05-06 and aren't happy. I say this because improperly high gearing puts unnecessary stress on your transmission, and adjusting shift points isn't going to help at highway speeds... and there will be even more stress on the tranny when encountering additional loads at higher speeds (e.g., inclines, etc.).

 

[Hasselblad]

I don't know what "tromp" means in this scenario, but if you have to stomp it to kick it back down to 3 when going less than 45+mpg, your 4-3 kickdown isn't programmed as high as it probably should be (or you have something else weird going on). A gradual push of the throttle downshifts mine out of OD when cruising up to about 40mph or so, and the "pedal push" and "downshift" process is very smooth and natural. This is the case until I'm up around 50mph+ in OD (since I don't want it to kickdown at highway speeds).

That said, it's best to get your gearing in order, then dial in the shift points if you have an 05-06 and aren't happy. I say this because improperly high gearing puts unnecessary stress on your transmission, and adjusting shift points isn't going to help at highway speeds... and there will be even more stress on the tranny when encountering additional loads at higher speeds (e.g., inclines, etc.).

I think you misunderstood. I do not have the kickdown issue (there is no mechanical kick down on my jeep) anymore as the tuner adjustment allows my system to do it when floored and in lug mode at ~50. Regarding gearing and shift points, it is currently dialed in with my 4.10, and will be adjusted if need be once the regear is complete.

 

[MikeE024]

I think you misunderstood. I do not have the kickdown issue (there is no mechanical kick down on my jeep) anymore as the tuner adjustment allows my system to do it when floored and in lug mode at ~50. Regarding gearing and shift points, it is currently dialed in with my 4.10, and will be adjusted if need be once the regear is complete.

Maybe you misunderstood my response.

You didn’t provide key information (your speed) until after I pointed it out. That’s solved now.

Whether or not you readjust your shift points after the regear isn’t important to me. What matters is that we encourage future readers to do the regear first since that’s the correct way for reasons I already explained. It might not be intuitive to you, but it’s important that we explain the proper order so ignorant readers don't mistakenly think adjusting the shift schedule is a good method for pushing back or entirely skipping a regear. It isn’t and that should be made very clear.

 

[Hasselblad]

You didn’t provide key information (your speed) until after I pointed it out. That’s solved now.

https://wranglertjforum.com/threads...-and-other-re-gearing-faqs.17063/post-1831138

I had to go back and check, as I have been hopping back and forth between threads.

In any event, the tuning allowed me to stomp my way out of the upgrade lug once the fooking tanker trucks get into the right lane, even without OD turned off. Before the tune stomping did little more than waste gas, after tune I can get it to jump to 3rd gear and get back up to normal speeds.

Even without accounting for the steep grade lugging "fix" the tune really helped all around shifting of the 42rle in normal non-highway driving. Was noticeable.

 

[Hasselblad]

https://wranglertjforum.com/threads...-and-other-re-gearing-faqs.17063/post-1831138

I had to go back and check, as I have been hopping back and forth between threads.

In any event, the tuning allowed me to stomp my way out of the upgrade lug once the fooking tanker trucks get into the right lane, even without OD turned off. Before the tune stomping did little more than waste gas, after tune I can get it to jump to 3rd gear and get back up to normal speeds.

Even without accounting for the steep grade lugging "fix" the tune really helped all around shifting of the 42rle in normal non-highway driving. Was noticeable.
Edit: and to be clear, the retune was solely based upon existing gearing/tires/engine/transmission, not what it would be in the future.

 

[Hasselblad]

I've seen posts where dana spicer gear sets have been recommended but I am having a heck of a time googling sets for 2006 rubicons. Do these exist?
Trying to find a high end alternative to the unobtanium revolution 5.13 sets.