5.13 with 33's

[Dusty Rag]

Hey All,

Looking for people to tell me if this is a good idea or not. I drive mostly city/trails with a typical trip to a trail/park under 200miles. I'm pretty unhappy with the v6/4.10 gear pairing in my JTR 6-Speed manual. I think 4.10's would be good if the v6 made more torque down low but it just doesn't have the snot to get it all moving. I also have a home built bed cap with a RTT (about 400lbs) and I load about another 200lbs of gear plus the family (wife and 2 kids.) I live in western PA (Pittsburgh) and travel around the tri-state area (PA, WV, OH, and sometimes NY and Virginia) so hills are very common and flat roads are rare.

Future may hold 35s but I have no desire to go any bigger than that. I also have a 3000lbs (fully loaded) boat.

I don't seek out rock crawling but I also don't shy away from difficult trails if it means the better view/camping spot.

I've been playing around with different gears on the highway using 5th and sometimes 4th for a while to see what it's like for MPG's on the highway while the Pentastar is spinning 400-600 rpm's higher than 6th and from what I can tell it really feels like a minimal loss of about the same to no more than 2 mpgs lost depending on hills/flat ect. In all honesty, it really seems like vehicle speed impacts MPG's more than RPM increases. Having the aerodynamics of a shipping container seems to have the most drastic impact. Does anyone else feel that way?

MPG's really isn't all that important to me, I know what we all drive and have accepted that reality a long time ago. I also don't want to get like 8MPGs or cause harm to the v6/drive train by spinning it faster down the road if I can help it.

When I run the calculators I'm seeing about 600RPM increase at 75MPH when going 5.13 and 33s over the stock configuration.

Here's a couple pictures of the rig fully loaded and an excel snip of my calculations.

Curious on your thoughts.

Thanks!

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[bleda2002]

Jeep already offers 4.88s for manuals on 31 inch tires in the wrangler, so 5.13's should be fine. Just a bit lower highway mpg, and as you said, you'll be ready for 35's.

 

[LouisvEarlleJT]

Your note on RPM’s not mattering as much as speed is spot on I believe My understanding is that these motors make more power higher in their RPM band than other similar setups, I.e. that you have to “stay in it” longer or “get on it” harder to experience said power.

That being said, before dropping the $$ on a regear, have you considered switching up how you drive the truck? Basically push it a bit harder?

 

[Hootbro]

That is a lot of stuff. Have you actually weight scaled it loaded with everybody fully loaded out?

 

[Dusty Rag]

Jeep already offers 4.88s for manuals on 31 inch tires in the wrangler, so 5.13's should be fine. Just a bit lower highway mpg, and as you said, you'll be ready for 35's.

Your note on RPM’s not mattering as much as speed is spot on I believe My understanding is that these motors make more power higher in their RPM band than other similar setups, I.e. that you have to “stay in it” longer or “get on it” harder to experience said power.

That being said, before dropping the $$ on a regear, have you considered switching up how you drive the truck? Basically push it a bit harder?

I actually have. Out of all the manuals I've had, I have to work this one the hardest. Just feels like I'm really flogging it to get it going. That in it self feels like abuse to the drive train lol.

 

[Dusty Rag]

That is a lot of stuff. Have you actually weight scaled it loaded with everybody fully loaded out?

I have not. This is a bit overly drastic to the normal scenario. Took this for a family beach trip to OBX so a bit more gear than typical camping trip.

 

[Hootbro]

I have not. This is a bit overly drastic to the normal scenario. Took this for a family beach trip to OBX so a bit more gear than typical camping trip.

I have seen worse on some of the weekend shore traffic here in Delaware. I know the State Police here will be all up in peoples business if they come across an accident with a vehicle all loaded out and looking like they may be exceeding their GVWR.

 

[ericnewcom]

I'm running 5.13s on 33" tires 6 speed Rubicon. I plan to go to 35s when the 33s need to be replaced but for now the 5.13s work well. I really thought it would be slower in 1st and reverse than it is. I can still run 70/72 mph no issue. I have a 75 f250 that is still half the speed at idle in 1st and reverse and it has 4.10 gears. Ford actually geared the transmission for truck and offroad use back then. Oh and the 75 will still get out and cruise 70+ just as easy as the jeep. If I didn't have 2 car seats the 75 would still be my daily and will be again one day.

 

[Dusty Rag]

I have seen worse on some of the weekend shore traffic here in Delaware. I know the State Police here will be all up in people business if they come across an accident with people all loaded out and looking like they may be exceeding their GVWR.

You're right, I probably should do the math at least.
GVWR = 6250lbs
Curb Weight = 5050lbs
Carry Capacity = GVWR - Curb Weight
Carry Capacity = 1200lbs

Fuel = 6lbs per gallon * 22gal = 132lbs
All 4 passangers (Me, Wife, 1.5year old, and 2 year old) = 430lbs
RTT = 150lbs
Bed Cap = 250lbs
Gear = 200lbs

Cargo Weight = 1200 - 132 -430 - 150 - 250 - 200 = 38lbs left for snacks.

?, I'm getting close.

 

[Dusty Rag]

I'm running 5.13s on 33" tires 6 speed Rubicon. I plan to go to 35s when the 33s need to be replaced but for now the 5.13s work well. I really thought it would be slower in 1st and reverse than it is. I can still run 70/72 mph no issue. I have a 75 f250 that is still half the speed at idle in 1st and reverse and it has 4.10 gears. Ford actually geared the transmission for truck and offroad use back then. Oh and the 75 will still get out and cruise 70+ just as easy as the jeep. If I didn't have 2 car seats the 75 would still be my daily and will be again one day.

That's great to hear it's worked out well for you.

I agree on 1st. It really doesn't feel like it's actually 5.13:1. That's actually more of a granny gear in first than Jeep has put in in a long time.

 

[JTDay]

IIRC, the cams go from low to high lift mode around 27 or 2800 RPM. 5.13s, 33s, 6MT will have you at 2800+ tomorrow at 75mph. I'm not sure what impact that might have but just something I'd note and consider if I were you.

 

[Dickster]

Pro charger?

 

[smlobx]

What about 4.88 gears?

 

[Minty JL]

5.13s on 33" tires seems to be a bit of an overkill. But its your rig.

I have 37x13.5 17 on the factory 4.10 and it does damn good. I have either 4.88 or 5.13s in my future because I might jump up to 39s or 40s in the future

 

[Jteakus]

We did one with an auto, 5.13's and 35's, owner loves it.

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