tgoss

Hey guys, just swapped in a set of dynatrac axles bought from a forum member who had them installed with 5.38 gears and I noticed this past week I'm now running very warm while climbing uphill gradients at freeway speeds.

Specs on my rig:

2013 JKU Moab
Stock 3.6
Auto Trans
Superchips Flashpaq
PR44 Front
PR60 Rear
5.38 Gears
37" BFG K02's
3.5 Rubicon Express Lift
PSC Bumpers, Winch, Aluminum Rockers, Aluminum Fenders, Rear bumper w/ Carrier and spare (Added to list for weight purposes)

Here's what I'm seeing and it's possibly normal for my setup, this is my first JKU just looking for feedback from anyone who has experienced anything with similar components.

I will start a long hillclimb and the Jeep doesn't seem to know what gear it wants to be in during the climb. Struggles in 5th obviously because of the weight of the rig but 4th almost revs too high keep a 60-65mph pace at around 3500-3750 RPM's. As this goes on I can watch the water temps climb pretty drastically.

All this has started happening after the axle swap so I'm thinking I maybe geared too high? The guy I bought them from was very cool and threw in a set of 5.13's so should I try these or maybe look at dropping down to 4.88's? Maybe it's just normal and I should look at upgrading some of the cooling components to keep temps down (I do have a 10A hood with the vents completely chopped out).

Also in addition to this the trans shift points are all sorts of fvcked up. I don't know if the flash cal can fix this but seriously it's getting on my nerves how the rig refuses to upshift sometimes.

Any help or insight would be greatly appreciated!

Joe_B

Your gearing is too low with the 3.6 + auto for your 37s so you'll be running at a higher RPM than you need be. This will generate excess heat as you've seen.

You also need to tell the jeeps computer you're running different gearing. This should improve shift points.

I would either regear but the 5.13s will be a bit low or man up and buy 40s lol

Good luck

nthinuf

That's where you should start, then drive it and report back.

Are you still using TPMS? Flashcal will not adjust the psi anymore, just on/off. Procal isn't fancy, but does the job just fine. And if you want a tuner instead of just a programmer, look at the flashpaq or intune.


Not many people with the 3.6 are running 5.38's. (you are the first I have seen on this forum...) If you have the skills to install those 5.13's, might not be a horrible use of a day. But, I'd reprogram it first and see what you think.

tgoss

The superchips flashpaq (sorry I know I initially said flash cal) does allow me to change the gear ratio and tire sizing so that has been done.

I may just find break down and do 4.88's. That was my initial thought but figured I would run these as is since they were already installed.

Man, would love to run 40's but these axles stretched the piggy bank to begin with and I would NEED more power. I went with these so I could run 37's without much worry but I think 40's on these semi-floats would be pushing my comfort levels.

Thanks for the input guys.

Rebar-7

Yeah think 5:38's are way to much gear. The 5:13's would be better since you have them , but if you have to pay someone to do the switch still money out of pocket, dang..

mhockey9090

If you're running 37s, just bump down to 5.13 instead of 4.88s. Unless you want a better gearing for highway and auto.