It’s time to get rid of my 4.10:1 gear set. With 37’s, it’s too sluggish for the streets. So, I’m considering doing it myself. I’ve seen a few videos and it doesn’t seem too bad aside from the time investment. Luckily my kiddos are starting to sleep well at night so I have evenings available to do Jeep work. I think a few evenings of work will get the job done.

What brand(s) of gears are best for our Jeeps? I’ve had good luck with Yukon when I was in the Toyota world. Yukon has their YES program, basically a lifetime warranty on the gears.

Anyone have experience with rem polishing? Is it a scam to avoid breaking in gears or is it legit and worth it?

 

Yukon or Dana/Spicer I have good luck with both but long times back. Old mechanics have always told me the break in is a good thing but only where you don't tow, or go hard on the gears. They say 200kms of stop and go driving then check wear patterns and oil flush / change.

 

Based on what you've done so far, I'd say you can do this yourself......though it is nicer if it's not a DD and you have as much time as you need. It also helps to have a lift or not be working on the garage floor as there can be a lot of installing and pulling the carrier and it sucks on the floor.....but that is what it is. My preference is Yukon, but I also think more important than brand of gears is quality labor, ya know. You going to go with 4.88 or 5.13?

 

Two votes for Yukon, that’s good enough for me. Haha. I don’t think I’ll mess with the rem polishing or anything else. My gut tells me that if I do a simple break in as the instructions suggest then I’ll be fine.

The plus side of me doing this myself is that I can justify buying a 20 ton floor press and some fancy bearing puller adapters.

I’ll use a 5.13 gear set by the way.

 

Yukon is fine, Revolution too. I wouldn't do it yourself without a shadow. I had 37s (recently jumped in tire) for years...I went 4.88s and regretted it. Wished I had gone 5.13s.

 

I had 5.13s in my old axles with 37s. Loved the low end, the top end wore on me but I do a decent bit of 70+ mph driving. An axle swap downgraded me to 4.88s. At first I kinda liked that better, but the more I tow my little trailer around, the more I do miss my 5.13s.

 

I’m gonna give it a shot at doing it myself, I don’t think it will be a big deal. Remove carrier (mark caps for position and orientation), remove pinion shaft, remove bearings, clean clean clean. Replace new bearings, install pinion and set preload, install carrier using same shims as prior for first start, set backlash, adjust shims to obtain proper backlash then check gear mesh pattern. Easy peasy.

I do mostly city driving but also do some freeway too. But where I’m at, the freeway is steep hills so I don’t get to 70mph much with my gearing. I think when I get my new gears installed I’ll have a much better time getting to speed on a hill. Besides, I don’t think I ever even see 6th gear now so I’m driving around 4500rpm in 5th speed anyways just to keep up with traffic. I think I’m gonna appreciate the 5.13’s over the 4.88’s.

Everything is ordered and should be here by the end of the week. Hoped by the end of next week (working a couple hours each evening) I’ll have new gears installed.

I’ll do my best to document everything and make it look easy for anyone else who may think that they shouldn’t do it themselves.

 

Probably telling you things you already know here, but anyhow:

- bearing caps are already stamped with a letter horizontal or vertical and machined side always goes in, so those are hard to get mixed up, but you might mark the bolts to make sure they get back in the same place.

- It seems that most of the time simply reusing the existing pinion shim works fine, especially when you're not totally replacing the carrier, but most "tutorials" would say to use some set up bearings until you have that shimming confirmed with the first pattern before pressing on the new bearings.

- Anytime a ring gear is removed, I find it helpful to get the new one in place, install all bolts so the ring gear is fully seated, THEN back them out one at a time to install red loctite. I had a situation one time where kept getting a fleck of loctite between the ring gear and carrier when trying to simply put LT on the bolts installing them sequentially before the gear was 100% in set in place which took time troubleshooting to figure out why backlash around the gear was uneven by a decent margin.

There are obviously plenty of videos on YouTube, and decent writeups on Pirate from years past. YT Channel The BFH Garage showed up in my stream one day and that guy has a couple decent documentations of D30/44 regears. It's a task that most of gen pop isn't up for, but it's definitely not rocket science and you are plenty capable.

 

Digging up this old thread. I really can't recall if you completed your transition to 5.13s or not. I was looking for another thread in which you were talking about this 3.6L in general lacking power and just wanting, or having, to keep it up around 4500 rpm. I know there was another thread but kept landing on this one due to my search.

Anyhow, I'm hitting the point of being tired of these 4.88s when it comes to towing my trailer. Had to hook up the utility trailer this week and it's amazing what a turd this is even with an empty 5x10 utility trailer behind it. The last few big trips I've taken with my trailer it's really set the thought in my head that you're gonna be running high rpms regardless of being geared properly and having to downshift constantly or by just generally being undergeared. That leads me to my recent potential resolution flirtations.

I have always been anti forced-induction. I have a friend that has a RIPP and though he loves the thrill ride, he's struggled with shifting issues for years and trying to get it tuned properly. He's been through the gammit and the last attempt he put the brakes on the effort at $500 in labor for attempting to get it nailed. I have another buddy that has had all sorts of setups, Sprintex, Prodigy, RIPP. I've contemplated if taking that dive might be the answer to my issue but both of these guys tell me no, it's not worth it. I've seen first hand the additional wear on the engine and the unreliability, and they tell me on that top end I'd only be seeing ~2lbs boost and that isn't going to make the difference. It's generally a lot of money for a gamble and I agree it's just not worth it.

That leads me back to gearing. The time and effort to go to 5.13s from 4.88 will never be worth it, and that extra 100-150 rpm isn't going to make a hill-of-beans difference in my towing performance IMO. That leads me to contemplate 5.38s. That would be pretty undergeared for my 37s. It's not really a DD these days, but it does see long trips on the interstate every now and then when I go on adventures. I drove it to work this morning and forced it to stay in 4th gear. Traveling ~80mph put the engine around 3700rpm and that is where I estimate I'd land with 5.38 gears. I think I could stand the engine noise as my jeep is about as utilitarian as it gets, but one thing I thought about this morning was oil pressure. Running that rpm range puts my oil pressure up in the mid-70s, completely normal IMO and not a concern when downshifting, but I'm kinda thinking that could be a concern if that is just where it is all the time vs. short periods of downshifting.

If I'm running that high constantly do you guys think I am just asking for premature engine failure?

 

I wouldn't go at this as a rookie. There's WAY more horror stories than not. It is simply not worth it. Backlash setting (and tooling) and spacing are very crucial. I do all my own work, and that is one I outsource. And I was a tech for 15yrs.

That said...Revolution, Yukon, Dana, G2...all good to go.

37s and JKs....I don't recommend anything under 5.13s. It'll still be a dog with 4.88s.