Starting a 6.4 Hemi swap

[RudeJeepin]

I am relooking the gear ratio thing.

Look at the following numbers:

5.13 40.0" 70mph 2000rpm
5.13 39.5" 70mph 2050rpm

4.56 37.0" 70mph 1950rpm
4.56 36.5" 70mph 1970rpm

5.13 39.5" 75mph 2200rpm
4.56 36.5" 75mph 2100rpm

I have used the standard rounding error. 69.62mph = 70mph

Now look at the offset. A 40" tire, which is usually 39.5" in diameter, using my current 5.13 gears, is pretty close to the 4.56 with a 36.5" diameter tire! I mean, it is so darned close that if there were no other factors, it would suggest moving up to 40" tires and keeping the current gearsets.

I'll have over 350 ft lbs available at cruise RPM. Does the 3.6 even produce 100???

I really have to think this through. I know the 40" tire is going to weigh more, but how much more?? Will it make a significant enough difference to warrant other changes? Larger brakes come to mind, but I already have the best forged axles made, residing in the housings. I don't hammer on my Jeep, so in my view, the D44s would work just fine. And these late-model D44S are pretty close to the D60s of yesteryear...They're butt strong!

I know the Hemi in low range with my 4.1 Rubicon case will like to "push through" the brakes, but I have heard to place the transmission into manual and use 2nd gear instead of first. So that solves all of that.

I couldn't carry a 40" tire under the bed in the stock location, but moving it to the bed would yield more departure angle and ground clearance.
Losing the bed space is an issue with the rooftop tent, but I am looking at upgrading to a small camper to pull to a base camp, then dropping it and taking off in a lightweight, not-so-top-heavy JT.

This is classic foot bone is connected to the leg bone thinking, but I have to think about the JT as a system. So when I tickle the tire size, the thermostat reacts!

Ah, the perverbial can of worms.
I think we've all been there. I'm was there with my shocks. Now I'm at the snowball effect phase.

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[LouisvEarlleJT]

I am relooking the gear ratio thing.

Look at the following numbers:

5.13 40.0" 70mph 2000rpm
5.13 39.5" 70mph 2050rpm

4.56 37.0" 70mph 1950rpm
4.56 36.5" 70mph 1970rpm

5.13 39.5" 75mph 2200rpm
4.56 36.5" 75mph 2100rpm

I have used the standard rounding error. 69.62mph = 70mph

Now look at the offset. A 40" tire, which is usually 39.5" in diameter, using my current 5.13 gears, is pretty close to the 4.56 with a 36.5" diameter tire! I mean, it is so darned close that if there were no other factors, it would suggest moving up to 40" tires and keeping the current gearsets.

I'll have over 350 ft lbs available at cruise RPM. Does the 3.6 even produce 100???

I really have to think this through. I know the 40" tire is going to weigh more, but how much more?? Will it make a significant enough difference to warrant other changes? Larger brakes come to mind, but I already have the best forged axles made, residing in the housings. I don't hammer on my Jeep, so in my view, the D44s would work just fine. And these late-model D44S are pretty close to the D60s of yesteryear...They're butt strong!

I know the Hemi in low range with my 4.1 Rubicon case will like to "push through" the brakes, but I have heard to place the transmission into manual and use 2nd gear instead of first. So that solves all of that.

I couldn't carry a 40" tire under the bed in the stock location, but moving it to the bed would yield more departure angle and ground clearance.
Losing the bed space is an issue with the rooftop tent, but I am looking at upgrading to a small camper to pull to a base camp, then dropping it and taking off in a lightweight, not-so-top-heavy JT.

This is classic foot bone is connected to the leg bone thinking, but I have to think about the JT as a system. So when I tickle the tire size, the thermostat reacts!

What are you trying to do? Because the offroad performance difference of a 36.5" tire and a 40" tire (if I'm reading your range correctly) is fairly minimal.

 

[Rcoe]

Keep the 5.13's upgrade to 40's. Keep your axles until something breaks, depending on how and where you drive that might be never.

You mentioned Pritchett Canyon, you will want the 40's on that trail. On these long JT's having a little extra tire size helps to keep from high centering. Plus they just look like the right size tire on a Gladiator.

 

[Flyin6]

What are you trying to do? Because the offroad performance difference of a 36.5" tire and a 40" tire (if I'm reading your range correctly) is fairly minimal.

Not really trying to do anything specific except to make the best decision possible.
The shop doing my Hemi swap suggested my 5.13's were too steep and recommended a 4.56. Cost $2399 for new ring and pinions.
That got me thinking it might be a better choice to go with bigger tires.
I'll drive the Jeep long distances, then hop on a trail for a week, then drive home. That is the typical usage for the Jeep since new.
From my experience, the 40" tire is for sure better, but as you suggest, not "crazy" better.
I'm sort of doing a clean-slate, fresh-paper inventory of my JT. The suspension will not change now that I have it long-armed. The shocks may, but nothing else. The axles will stay, as will most of the body. The engine, transmission, and possibly a driveshaft or two may come as well.
I'm just examining the choices going forward.

 

[Flyin6]

Keep the 5.13's upgrade to 40's. Keep your axles until something breaks, depending on how and where you drive that might be never.

You mentioned Pritchett Canyon, you will want the 40's on that trail. On these long JTs, having a little extra tire size helps keep from high-centering. Plus they just look like the right size tire on a Gladiator.

I've never driven Pritchett Canyon, but another trail requiring more clearance is the Rubicon. And that one is in my gunsights for this truck.
I haven't broken many axles/differentials, comparatively speaking. A 9" Ford once, a 10-bolt once, well, a 9" twice now that I think about it. A Toyota rear differential, and another time (same axle), the ring and pinion. A couple of transmissions and a transfer case for good measure.

 

[AmosMoses]

Not really trying to do anything specific except to make the best decision possible.
The shop doing my Hemi swap suggested my 5.13's were too steep and recommended a 4.56. Cost $2399 for new ring and pinions.
That got me thinking it might be a better choice to go with bigger tires.
I'll drive the Jeep long distances, then hop on a trail for a week, then drive home. That is the typical usage for the Jeep since new.
From my experience, the 40" tire is for sure better, but as you suggest, not "crazy" better.
I'm sort of doing a clean-slate, fresh-paper inventory of my JT. The suspension will not change now that I have it long-armed. The shocks may, but nothing else. The axles will stay, as will most of the body. The engine, transmission, and possibly a driveshaft or two may come as well.
I'm just examining the choices going forward.

If I recall, Matt from Ozark Overland had 5.13's with 37" tires and when he did the amw 5.7 swap, he went back down to 4.56 gears and was happy he did after driving it. I wonder if you'd be better with 3.73 gears?

 

[Flyin6]

If I recall, Matt from Ozark Overland had 5.13's with 37" tires and when he did the amw 5.7 swap, he went back down to 4.56 gears and was happy he did after driving it. I wonder if you'd be better with 3.73 gears?

I'm sure you looked at the numbers I posted. It's a wash either way. 5.13 with new 40" tires or new 4.56 with my original 37s.
Here's what I am thinking at the moment: Keep the 5.13s and get new 40" tires. It's about the same cost either way, and by going to 40s, I get brand new tires. That makes the most sense to me at the moment.

 

[RudeJeepin]

Here's what I am thinking...by going to 40s, I get brand new tires. That makes the most sense to me at the moment.

I like the way you're thinking. New shoes are always good.

 

[40x40]

I am relooking the gear ratio thing.

Look at the following numbers:

5.13 40.0" 70mph 2000rpm
5.13 39.5" 70mph 2050rpm

4.56 37.0" 70mph 1950rpm
4.56 36.5" 70mph 1970rpm

5.13 39.5" 75mph 2200rpm
4.56 36.5" 75mph 2100rpm

I have used the standard rounding error. 69.62mph = 70mph

Now look at the offset. A 40" tire, which is usually 39.5" in diameter, using my current 5.13 gears, is pretty close to the 4.56 with a 36.5" diameter tire! I mean, it is so darned close that if there were no other factors, it would suggest moving up to 40" tires and keeping the current gearsets.

I'll have over 350 ft lbs available at cruise RPM. Does the 3.6 even produce 100???

I really have to think this through. I know the 40" tire is going to weigh more, but how much more?? Will it make a significant enough difference to warrant other changes? Larger brakes come to mind, but I already have the best forged axles made, residing in the housings. I don't hammer on my Jeep, so in my view, the D44s would work just fine. And these late-model D44S are pretty close to the D60s of yesteryear...They're butt strong!

I know the Hemi in low range with my 4.1 Rubicon case will like to "push through" the brakes, but I have heard to place the transmission into manual and use 2nd gear instead of first. So that solves all of that.

I couldn't carry a 40" tire under the bed in the stock location, but moving it to the bed would yield more departure angle and ground clearance.
Losing the bed space is an issue with the rooftop tent, but I am looking at upgrading to a small camper to pull to a base camp, then dropping it and taking off in a lightweight, not-so-top-heavy JT.

This is classic foot bone is connected to the leg bone thinking, but I have to think about the JT as a system. So when I tickle the tire size, the thermostat reacts!

half a billion years ago when i was into drag racing, the mindset was "there is no replacement for cubic inch displacement"! 2" of height gain 36" to 40" is of the same mindset and it yields immediate results. if you can find full under body skid plates for your long arm system, you would be completely amazed at where you can go without fear of damage. yes, you still do it at 1.6 mph but it is so much more enjoyable.
the increased rotating mass of the larger tire does present the possibility of a myriad of problems but so does losing sleep over exactly when will our sun burnout. process your concerns accordingly. at 79 mph with 40s and 4.88 gears i'm at 2150 rpm in 8th gear. if i'm heading up a grade or have a strong head wind the jeep will select the best gear. as you stated you own the 5.13s and you are sensible when off road. i agree with your assessment of the d44. i drive mine with the same mentality with a strong bolstering of the fact i do not have d60s. also, i'm always in m1 - m2 when in 4lo. so much easier when braking.
i did not want to give up bed space for the spare as the gladiator is my only ride. i went with the Expedition One S3 bumper tire carrier and a cheap amazon hitch skid plate. departure angle problem solved.

 

[Flyin6]

half a billion years ago when i was into drag racing, the mindset was "there is no replacement for cubic inch displacement"! 2" of height gain 36" to 40" is of the same mindset and it yields immediate results. if you can find full under body skid plates for your long arm system, you would be completely amazed at where you can go without fear of damage. yes, you still do it at 1.6 mph but it is so much more enjoyable.
the increased rotating mass of the larger tire does present the possibility of a myriad of problems but so does losing sleep over exactly when will our sun burnout. process your concerns accordingly. at 79 mph with 40s and 4.88 gears i'm at 2150 rpm in 8th gear. if i'm heading up a grade or have a strong head wind the jeep will select the best gear. as you stated you own the 5.13s and you are sensible when off road. i agree with your assessment of the d44. i drive mine with the same mentality with a strong bolstering of the fact i do not have d60s. also, i'm always in m1 - m2 when in 4lo. so much easier when braking.
i did not want to give up bed space for the spare as the gladiator is my only ride. i went with the Expedition One S3 bumper tire carrier and a cheap amazon hitch skid plate. departure angle problem solved.

Excellent logic
Are those 40s you have on your JT?
I think I have made a decision regarding this topic, and that is to move to the 40" tires. Simple enough...Since I have real beadlocks, I'll just do the tire swap myself.
On the subject of where I might mount that spare, well, that's a different story. Completely undecided there.
My current setup, which the wife is arguing to keep, is an IKamper roof-top tent. With that configuration, I need bed space for all her shoes, makeup, more shoes, and some spare shoes! I have all our "Overland" stuff in plastic bins and have that packing list pretty well fine-tuned.

My concept of the operation going forward is to add a smallish MDC or Pause travel camper to a tow hitch I will now have to reinstall. Tow that thing to Basecamp, then detach, air down, and head out to Funville. One little problem is that the towable might not agree with some of the multiday adventure trails I am looking at. Of course, I could go with a bumper mount as well...ahhh, so many decisions!

 

[40x40]

Excellent logic
Are those 40s you have on your JT?
I think I have made a decision regarding this topic, and that is to move to the 40" tires. Simple enough...Since I have real beadlocks, I'll just do the tire swap myself.
On the subject of where I might mount that spare, well, that's a different story. Completely undecided there.
My current setup, which the wife is arguing to keep, is an IKamper roof-top tent. With that configuration, I need bed space for all her shoes, makeup, more shoes, and some spare shoes! I have all our "Overland" stuff in plastic bins and have that packing list pretty well fine-tuned.

My concept of the operation going forward is to add a smallish MDC or Pause travel camper to a tow hitch I will now have to reinstall. Tow that thing to Basecamp, then detach, air down, and head out to Funville. One little problem is that the towable might not agree with some of the multiday adventure trails I am looking at. Of course, I could go with a bumper mount as well...ahhh, so many decisions!

yes they are Maxxis AT 40x13.50x20 and i enjoy their on and off road manners. they are my second set. i put 40k on the first. the lowest price for these hides is at walmart.com! who would have guessed.
when i did the build i installed jeep's heavy hitch. it is compatible with the new bumper.

 

[Flyin6]

yes they are Maxxis AT 40x13.50x20 and i enjoy their on and off road manners. they are my second set. i put 40k on the first. the lowest price for these hides is at walmart.com! who would have guessed.
when i did the build i installed jeep's heavy hitch. it is compatible with the new bumper.

I cut out the factory hitch when I bolted on the rear bumper, so there's that.
I could build or buy something that runs the hitch point through the bumper to save ground clearance, but first I'll need to figure out which direction I am going to be told I'm going :-(

Favoring Patagonia MT's at the moment...

 

[Flyin6]

Making decisions daily!

I'm moving up to the 40's and leaving the 5.13's in there for now.

I was immediately faced with the spare tire dilema. Good news: The underside of the bed is gonna get a lot cleaner.
Bad news: No place to put the spare that doesn't take up bed space or add a ton of weight

Then...

I found this:

This is a cool tire carrier that replaces the rear tailgate. What I like about that is the fact that at least I lose some weight while gaining some with this replacement steel part which has to weigh a bunch more than the tail gate.

 

[Rcoe]

That is one of the nicer options I have seen, better than the bumper mounted ones. But it still puts a lot of weight way out on the backside.

I just don't run a spare unless I am making a trip.

 

[MSFTMatt]

Making decisions daily!

I'm moving up to the 40's and leaving the 5.13's in there for now.

I was immediately faced with the spare tire dilema. Good news: The underside of the bed is gonna get a lot cleaner.
Bad news: No place to put the spare that doesn't take up bed space or add a ton of weight

Then...

I found this:

This is a cool tire carrier that replaces the rear tailgate. What I like about that is the fact that at least I lose some weight while gaining some with this replacement steel part which has to weigh a bunch more than the tail gate.

I have the Expedition One Dual Swing out and had the Shift AutoWerks frame brace installed. The parts are less then 1k and from what I’ve seen you can do the install yourself

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