5.13s or 5.38s with what tire size and why?

[Bonanza]

Yeah I can see that you used them like that. That went without saying.

But you’re wrong. It’s not a matter of can you do it, it’s a matter of should you. And you shouldn’t. You do you tho - not my Jeep. I just care enough to make sure other people don’t follow that advice.

Your advice is people shouldn't wheel unless they unnecessarily re-gear? I browsed your post history to see what sort of support your posts might give to your opinions, but all I see you telling people what they should be doing, and shitting on things you don't like or approve of. That, and your jeep parked on level roads.

All I have is doing some of the hardest rock trails in the country, working in my family mechanic shop, building three of my own Jeeps, etc.

I'll be sure you remember your advice when I'm out there wheeling.

Bonus:
Me axle swapping my JKUR. On 4.10s!!

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[BLK HOLE]

Your advice is people shouldn't wheel unless they unnecessarily re-gear? I browsed your post history to see what sort of support your posts might give to your opinions, but all I see you telling people what they should be doing, and shitting on things you don't like or approve of. That, and your jeep parked on level roads.

All I have is doing some of the hardest rock trails in the country, working in my family mechanic shop, building three of my own Jeeps, etc.

I'll be sure you remember your advice when I'm out there wheeling.

You're right...I should definitely get out and Jeep more around the country and try new terrains! Hahahaha. And most of these pics are quite recent (a couple were from this weekend)...I just didn't want to flood the thread with my pics. Your little rock mine field pics are cute and all...

I still own 2 of the 3.

And no my advice isn't to shut down activity if you haven't regeared. Altho my advice WOULD BE to add regearing into any tire change budget. Thats just proper modification form. You even said as much yourself to start this conversation. You're saying "its fine"...well yes...you CAN do it. But you really should regear. And you'll die alone on that hill arguing against it. Anyone with any real experience wouldn't agree with me.

 

[Bonanza]

Sick! ^ Love it. A good D-wagging contest is always appreciated. Well done.

 

[1996XJ]

Which mall did you meet him at Joking aside I have yet to hear the four tens rhetoric when out wheeling with other folks.

The crazy thing is he used to build jeeps back in the day and his brothers team built a Gladiator that raced in the baja 500. He simply told me that he drives it like 60 miles a day to and from work and its runs fine. I personally would be scared to hurt my transmission and engine. But its one thing i cant get a straight answer on from anyone. Does running the wrong gear just make your jeep a dog up hills and a gas guzzler or are you hurting the transmission? I feel like it has to be taking life off the jeep to run huge tires without a regear but i dont know much about building jeeps to be honest.

 

[bakobobby]

The crazy thing is he used to build jeeps back in the day and his brothers team built a Gladiator that raced in the baja 500. He simply told me that he drives it like 60 miles a day to and from work and its runs fine. I personally would be scared to hurt my transmission and engine. But its one thing i cant get a straight answer on from anyone. Does running the wrong gear just make your jeep a dog up hills and a gas guzzler or are you hurting the transmission? I feel like it has to be taking life off the jeep to run huge tires without a regear but i dont know much about building jeeps to be honest.

That is funny he for sure knows the benefits guessing just doesn’t want to shell out and/or put in the work? Think you only have to worry about damage if you are roughing it off road. As I understanding it is the having to spin things up much higher that present opportunities for failure. On the positive side if you are not using 7th and 8th gear they can’t break

 

[SF_E60]

Glad I found this thread. I'll be regarding soon and wasn't sure if I should go 4.88 or 5.13. On my JK I had regeared to 4.88 on 35's which was okay. Now I'm on 37's and wasn't sure if 4.88 was going to cut it. But looks like I'll be going 5.13's

 

[WILDHOBO]

Glad I found this thread. I'll be regarding soon and wasn't sure if I should go 4.88 or 5.13. On my JK I had regeared to 4.88 on 35's which was okay. Now I'm on 37's and wasn't sure if 4.88 was going to cut it. But looks like I'll be going 5.13's

You should be very happy with that setup.

 

[bleda2002]

I picked up the gladiator from being regeared to 5.13's on Friday and its a massive night and day difference. 37s on 4.10's was passable, 39's on 4.10's was miserable, but 39's on 5.13's is near stock feeling. I didnt expect to feel quite as much of a difference after the gears but its by far the best money i've spent on the jeep for liveability and satisfaction.

 

[metalry101]

I’ll throw My $.02 in the ring

5.13’s w/ 37’s is the the minimum gearing I would consider.

Now if you live at elevation like Denver, want to tow, or do a lot of off-roading, I’d go 5.38’s.

I have 2 out of 3 of these considerations and wish I would have gone 5.38. However, 5.13’s do just fine.

Either way, your hwy speed is going to be RPM limited, but I don’t care to drive it at 80 MPH anyway. Before that, I consider it aero limited. After 65, the drag on this brick is so bad your mileage tanks. I don’t want try an emergency maneuver at 80 either… not that 65 is any better for that.

This has been my experience and I plan to regear to 5.38 when I do axles. Now someone will say something about pinion head strength.

I know this thread is a month old, but does anyone else have an opinion on 5.38s? All the other opinions seemed to be about 5.13s vs 4.10s. Sure, 4.10s and 37s are fine, but 5.13s and 37s are much much better. If you don't believe me, well, my questions and opinions will seem dumb to you.

I'm trying to decide what to do with mine. 37's are as big as it will go for a long long time, but that said, I bought the Max Tow for a reason (other than not wanting to spend the extra 10k on a Rubicon). I have a ~5K camping trailer (loaded weight) that I drag around the mountains of Utah, and sometimes the YJ on a flatbed. I happen to agree with this guy that the Pentastar doesn't mind revs, and the truck HATES 80mph anyways, so being being undergeared for the highway isn't a concern for me at all.

My only concerns with 5.38s would be pinion strength, and maybe heat? I think I've read that really deep gears tend to run hotter (on long high speed drives) due to the increased revolutions (as opposed to something like 4.10s for instance)? Is there any truth to the latter concern? Anyone have any issues with strength of the pinion on the 5.38s?

My theory, and feel free to counter this if my logic is flawed, is that I don't have the 4:1 t-case so the 5% deeper gears will help in really technical terrain, but also help overcome not only the extra height of 37s, but the mass, width, and rolling resistance, especially while towing heavily. My truck tows awesome right now. It's not a rocket up hills, but it goes plenty well enough, and the trans and chassis control everything perfectly on downhill grades and in wind and such. I'd like to keep those characteristics if possible. It's always up the revs while towing anyways, so deeper rear end gears means it can do that in 4th instead of 3rd or whatever.

I've also thought about going 5.13 with 35s. Again, overkill, but with approximately 8 dozen overdrive gears in the trans and a general dislike of cruising at much more than 70 mph, it should be fine.

I know this is long winded, but, opinions, counterpoints, etc?

 

[WILDHOBO]

I know this thread is a month old, but does anyone else have an opinion on 5.38s? All the other opinions seemed to be about 5.13s vs 4.10s. Sure, 4.10s and 37s are fine, but 5.13s and 37s are much much better. If you don't believe me, well, my questions and opinions will seem dumb to you.

I'm trying to decide what to do with mine. 37's are as big as it will go for a long long time, but that said, I bought the Max Tow for a reason (other than not wanting to spend the extra 10k on a Rubicon). I have a ~5K camping trailer (loaded weight) that I drag around the mountains of Utah, and sometimes the YJ on a flatbed. I happen to agree with this guy that the Pentastar doesn't mind revs, and the truck HATES 80mph anyways, so being being undergeared for the highway isn't a concern for me at all.

My only concerns with 5.38s would be pinion strength, and maybe heat? I think I've read that really deep gears tend to run hotter (on long high speed drives) due to the increased revolutions (as opposed to something like 4.10s for instance)? Is there any truth to the latter concern? Anyone have any issues with strength of the pinion on the 5.38s?

My theory, and feel free to counter this if my logic is flawed, is that I don't have the 4:1 t-case so the 5% deeper gears will help in really technical terrain, but also help overcome not only the extra height of 37s, but the mass, width, and rolling resistance, especially while towing heavily. My truck tows awesome right now. It's not a rocket up hills, but it goes plenty well enough, and the trans and chassis control everything perfectly on downhill grades and in wind and such. I'd like to keep those characteristics if possible. It's always up the revs while towing anyways, so deeper rear end gears means it can do that in 4th instead of 3rd or whatever.

I've also thought about going 5.13 with 35s. Again, overkill, but with approximately 8 dozen overdrive gears in the trans and a general dislike of cruising at much more than 70 mph, it should be fine.

I know this is long winded, but, opinions, counterpoints, etc?

I like the theory that you’ll get a better crawl ratio, as you’re starting without the 4:1 t-case, but I can’t speak to pinion strength. I can say that with 5.13’s and 37’s, mine tows great with a 3,300lb trailer and a really loaded bed. As you said, 80 is the max comfortable speed in Colorado or Utah, but I prefer 77. I’m not slowing down for gas mileage; but I definitely see higher gears when towing, but not up passes of course. It doesn’t win races up vail pass or similar, but it does what I want it to. The crawl ratio alone is worth it to me to be in a higher ratio diff gears.

 

[WK2JT]

I like the theory that you’ll get a better crawl ratio, as you’re starting without the 4:1 t-case, but I can’t speak to pinion strength. I can say that with 5.13’s and 37’s, mine tows great with a 3,300lb trailer and a really loaded bed. As you said, 80 is the max comfortable speed in Colorado or Utah, but I prefer 77. I’m not slowing down for gas mileage; but I definitely see higher gears when towing, but not up passes of course. It doesn’t win races up vail pass or similar, but it does what I want it to. The crawl ratio alone is worth it to me to be in a higher ratio diff gears.

Vail pass just hurts. Agreed, 5.13’s work and I wouldn’t want anything less on 37’s. I’m going to hold off on the 5.38’s until after I put the KO2’s on. They are 13 lbs lighter a tire. Those with the livernois 91 octane tune might be just enough to leave it alone. If I was to do it over again though, I would have gone 5.38’s.

As for pinion strength, I read somewhere that the 4.88, 5.13 and 5.38 all use the same pinion, just different ring gear. However, that was about 2 years ago and I didn’t book mark the reference for the Dana gears.

 

[SF_E60]

Re-geared last Friday to 5.13 wow! Night and day difference. I've noticed improved mpg's city driving breaking in the gears. The shifting feels so much better now. Can't wait to do my first fluid change (500 mile) break in period.

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