resharp001

Pulling an axle shaft to replace a u-joint, or replacing the bearings isn't a big deal to do later on when/if they go bad. I mean, nothing says that you can't do it right now, but I'd just wait till they pose a problem since the labor to fix them later isn't a big deal. Who knows how much more life you could get out of them. Unless you're just hankerin' to spend some more money right now, I'd hold off.

jchappies

Try Taylor at old iron exhaust & Offroad.
https://www.yellowpages.com/el-cajon...road-522120662

MIT in El Cajon will do it too but may be pricey
and of course 4WP or ORW

OpenTrackRacer

I'll give him a call.

4Wheel Parts seems to do a complete installation with gears for $1299 but the 5.38's aren't listed. Waiting to see if they're eligible or not. It's a heck of a price...

jchappies

Rebel Offroad did my 5.38's. It's a little bit of a drive but they do gears all day long everyday almost so they have it down pretty good. Price was about 1K

jordy

5.38's seem like a lot of gear for 35's. Are you going to jump up in the future? I run 5.38's in mine and I'm a few clicks above in size.

Keep in mind that your 35's are likely 34's if you were to measure them as many tire manufacturers tend to exaggerate a bit in their sizes.

Just something to think about.

OpenTrackRacer

Yeah, my Duratracs measure out to around 34 inches. With the 3.8 engine and four speed automatic the Jeep was anemic when it was stock. Now with bigger tires and a lot of extra weight (I'm well over GVWR on a trip) it's downright pathetic. Going up decent grades is a 2nd gear, 5,000 RPM affair and if they're long grades the engine starts to get hot. I'm looking for all the gearing I can get to offset that. I already get terrible mileage so I'm not worried about that!

jordy

I've got the same boat anchor under the hood. It will get an LS at some point, but I've been busy with other pursuits and it's not that high on my list at this point. I drive it to Moab for EJS from Phoenix and there are some good hills in between here and there, so I feel your pain as my girl isn't light either. I've got 5.38's on 40's though so I can still leg it out on the flats. She'll hit 100, it just takes some time. I'd be curious where you'd be on the road with that much gear and a substantially smaller tire. That's what I'm looking at. I'm thinking you might be letdown when you're revved way up at freeway speed. I just got back from SD so I know how you guys drive out there.

I didn't buy a Jeep for mileage either, but the LS would help that I keep telling myself.

OpenTrackRacer

Seems like there are different RPM charts out there so it can be hard to judge I think. Looking at old threads there are a lot of people with ~35" tires and 5.38 gears that are very happy. In fact, there were many posts of people with that setup wanting even shorter gears.

Loaded up for a trip I'm right around 6,000 pounds so I'll take everything I can get!

jordy

Yeah, lots of charts for sure! You guys have a bunch more hills all over the place, so it makes sense. I should probably scale mine at some point, but I'm above 6K if I had to make any kind of a guess.

On the bright side, if it proves to be too much on the gear side, it's easy to play with tires and pick up inches here and there and get the perfect setup that way.

nthinuf

Can't speak to the accuracy of any other charts to be found, but the one for the 3.8 auto that JPop made (stuck in the FAQ's at the top of this modified area) has been pretty accurate for me through three gear ratios and five tire sizes.

It shows 5.38's and 34" (measured height) to be around 2569 rpm at 70 mph.

Not a bad place to be, in my opinion. Then again, I may be a bit biased, since I tend to like a higher rpm than some other folks on the forum. And I rarely get much over 75mph. Certainly never been up near 100 in the JK.

Anyway, I ran 5.13's with tires that measured out to 32", and then 35's that measured 33.5". And ran 5.38's with those 35's for well over a year before finally moving up to 37's. Never had a problem of screaming high rpm's...