HO 3.73 vs 4.1?

[H3LZSN1P3R]

Yay, another sample of apples and oranges. Jeeps are not towing 20k+ trailers and the use case is not the same. Jeeps often have larger tires that will absolutely make use of the taller gears else they may be limited to about 50mph on the highway. Yeah, I own Jeeps, too. I am the first one that asked for it - yet no one has provided it.

The curves will come from a chassis dyno off wheel outputs resulting from the engine output through the entire drive line, not just the rear end. Within the usable speed bands when towing, what will the delta be between 4.10 and 3.73 at highway speeds pulling 20k up an 8% incline and what will the difference be when you are just 1 gear lower with the 3.73 vs the 4.10? Power difference? Doubtful. Fuel efficiency, likely a wash in this use case. All other use cases, better mileage and driving experience with the 3.73 unless you are always hauling around 39k or you have decided to increase the tire size from design and need to compensate.

Again, I know what taller gears can get you, but my argument is that they are not nearly as required as a lot of people on this forum seem to espouse they are. An aisin with 3.73 gears will work for anyone just hauling an RV and most folks hauling farm equipment for alfalfa. Just about anything else is just people getting into pissing contests.

Your signature doesn't indicate that you even drive either of these models I am asking about....why should anyone listen to your real-world experience based on the subject line of this thread???

Edited to add tire size as another reason to increase rear end ratio.

I would love to see the dyno results towing a trailer that is impossible…… i dont need to own the truck to drive it i haul all kinds of stuff for people with different trucks when I'm filling in for hot shot driving as favours to friends and what not… anything your 3.73 can tow the 4.10s will tow better period can the 3.73 do it sure but not as well.

 

[mbarber84]

@gimmie11s
@darrellr
@H3LZSN1P3R

If the three of you can’t have a civilized discussion without name-calling, taunting, making lewd remarks, etc. then please refrain from further engagements on this thread. Healthy discussion and debate are highly encouraged, childish name calling and taunting, posting irrelevant content, etc is beyond unacceptable. Especially considering all of you have a history of it. Tone it down, or put it to bed.

Consider this your one and only warning.

 

[Dave01]

Not an aisin HO, but I have a 6.4 hemi that I mistakenly ordered with 3:73’s, and I ultimately swapped in the 4:10’s. It is definitely a night and day difference pulling our 9500# camper up same grades we always do, and maintaining a certain speed. The 3:73’s would send the trans a few gears down and let the engine scream out of it’s power band to maintain speed, while the 4:10’s can maintain that same speed without as much effort out of the engine.
So no, taking off in 1st gear is most definitely not the only advantage of different rear gears in my actual real world experience with all else being the same, I don’t care how many different ways someone figures out the math and argues it on paper.

While mine came with 4.10, I still agree with your description 100%.

My main point coming in late on this discussion is this. There are only 2 reasons IMO why someone might prefer 3.73's - slightly better mpg unloaded, and running lower rpm on the highway. In years past with 4 speed automatics I'd opt for the loss of tow capability in favor of lower rpm cruising, I put a lot of highway miles on and "back then" with 4 speeds it was a significant difference in rpm and noise. Today with modern 8 speeds these trucks, gas or diesel, cruise effortlessly in 8th regardless of ratio. So I simply can't find a reason why I'd ever opt for 3.73. The argument that in certain cases 3.73 tows better simply doesn't hold up.

 

[gimmie11s]

While mine came with 4.10, I still agree with your description 100%.

My main point coming in late on this discussion is this. There are only 2 reasons IMO why someone might prefer 3.73's - slightly better mpg unloaded, and running lower rpm on the highway. In years past with 4 speed automatics I'd opt for the loss of tow capability in favor of lower rpm cruising, I put a lot of highway miles on and "back then" with 4 speeds it was a significant difference in rpm and noise. Today with modern 8 speeds these trucks, gas or diesel, cruise effortlessly in 8th regardless of ratio. So I simply can't find a reason why I'd ever opt for 3.73. The argument that in certain cases 3.73 tows better simply doesn't hold up.

Like anything... comes down to intended use. If primary tow rig, buy as much gear as you can. If you mix in a lot of unloaded driving, buy the numerically lower gear ratio.

 

[darrellr]

While mine came with 4.10, I still agree with your description 100%.

My main point coming in late on this discussion is this. There are only 2 reasons IMO why someone might prefer 3.73's - slightly better mpg unloaded, and running lower rpm on the highway. In years past with 4 speed automatics I'd opt for the loss of tow capability in favor of lower rpm cruising, I put a lot of highway miles on and "back then" with 4 speeds it was a significant difference in rpm and noise. Today with modern 8 speeds these trucks, gas or diesel, cruise effortlessly in 8th regardless of ratio. So I simply can't find a reason why I'd ever opt for 3.73. The argument that in certain cases 3.73 tows better simply doesn't hold up.

No one said 3.73 would tow better, the argument is that the 3.73 tows well enough in nearly all driving conditions that the 4.10 is not necessary with paired with the HO and aisin. The aisin is a 6-speed, not 8-speed. And it has a very deep first gear to help with take off (can stay in first gear and in the power band longer with the 3.73 than the 4.10).

 

[CdnHO]

Just buy what you want. It's your money and you have to live with it. If it doesn't perform to your expectations, it's on you. However last year a buddy of mine towed our fifth wheels 1700 miles from Michigan to Texas. His is an HO dually with 3.73 gears. My HO has 4.10 gears. His fiver weighed 17000 pounds while mine weighted 22,000. He followed me most of the time. When we got to Texas, he said he wished he had ordered 4.10s. Like I said, he ordered what he wanted. Hindsight is always 20/20.

 

[timelinex]

Hold on.... I was lazy before but looking more into the physics of this..... I'm pretty sure @darrellr is basically right. How fast you get moving will always be a factor of the torque you are providing to your wheels. In a closed system like a car, the torque will be entirely dependent on the torque curve. Assuming Peak torque is near the redline for our trucks. (let me know if it's not)

Everyone saying they are not having any issues getting to speed on hills are either not towing as heavy, as fast, or not towing up the same grade hills. We are talking about the Rocky Mountains, after all!

At the end of the day, shorter gears will rev up to redline faster which means you will have more opportunity to be in that peak of the torque curve. So the real advantage is

1. First gear where you can't downshift otherwise
2. Passing at various speeds. Since the gears are "shorter", you are more likely find a gear you can downshift to that puts you near peak torque, regardless of speed. I think this phenomenon is probably the reason people are adamant about 4.10's feeling faster during higher gears as well. Anytime you floor it, there is a bigger chance you will land into the top portion of your torque curve.

From there on in, which one does better at challenging situations like a hill will always be a matter of what speed you tow up hills at. When I'm at almost 60mph and it won' go any faster I am nearing redline. Which means I am basically right at peak torque as it is. A 4.10 can't help that. I'm already laying as much moving force onto the ground as my engine can provide. The multiplier doesn't change that. In fact, 3.73's may be the perfect gearing for my situation since I'm already in peak torque.

On the other hand, the 4.10's would have helped in the following situation that I mentioned in my post:

5. There was one time in the middle of a hill where I had to shed a lot of speed because of traffic, and it basically crawled at 48mph+ (hill ended before it got past 53 or something)

This happened because 48mph must be the exact intersection of

1. My RPM's are below the powerband of my torque curve
2. Shifting lower would put me above redline. So I can't

With a 4.10, I would have more likely had a gear I could shift down to that put me closer to the peak torque of the gear.

What do you guys think? Settled?

 

[timelinex]

Just buy what you want. It's your money and you have to live with it. If it doesn't perform to your expectations, it's on you. However last year a buddy of mine towed our fifth wheels 1700 miles from Michigan to Texas. His is an HO dually with 3.73 gears. My HO has 4.10 gears. His fiver weighed 17000 pounds while mine weighted 22,000. He followed me most of the time. When we got to Texas, he said he wished he had ordered 4.10s. Like I said, he ordered what he wanted. Hindsight is always 20/20.

I think your experiences hinges on the exact MPH in Texas and where it puts each gearset on the torque curve. There are bands of MPH where your buddy , towing your heavier rig, could possibly out pull you.

Check out my last post on the matter.

I agree that the 4.10 will, on average, have more bands of MPHs near peak torque. This means it will be able to pull a little harder in more situations than the 3.73 will. But ultimately, if both trucks are in the top of their torque curves, they will pull IDENTICALLY hard.

Unfortunately, it won't help the bulk of my complaint, and that is on steep hills when I'm stuck at ~60mph and sitting at PEAK torque as it is.

 

[CdnHO]

I think your experiences hinges on the exact MPH in Texas and where it puts each gearset on the torque curve. There are bands of MPH where your buddy , towing your heavier rig, could possibly out pull you.

Check out my last post on the matter.

I agree that the 4.10 will, on average, have more bands of MPHs near peak torque. This means it will be able to pull a little harder in more situations than the 3.73 will. But ultimately, if both trucks are in the top of their torque curves, they will pull IDENTICALLY hard.

Unfortunately, it won't help the bulk of my complaint, and that is on steep hills when I'm stuck at ~60mph and sitting at PEAK torque as it is.

We ran 65 from start to finish. His fuel mileage was a bit better but then we didn't buy the trucks because they were economy models.

 

[timelinex]

We ran 65 from start to finish. His fuel mileage was a bit better but then we didn't buy the trucks because they were economy models.

Outside of the few big hills where I'm stuck ~60mph, I'm running 65mph-77mph the entire time (basically try to keep within few MPH of speed limit). So speed isn't generally an issue for me either.....

 

[AH64ID]

@timelinex peak torque is not at/near redline but peak hp is.

SO/HO peak horsepower is at 2800 rpms
SO peak torque is at 1700 rpms
HO peak torque is at 1800 rpms

Torque curves are no longer relatively flat on these trucks. 1075lb/ft at 2800 rpms would be 573hp.

Going from my 18 with 3.42's to my 22 with 3.73's I can tell you that there is a huge difference just from the gearing. The 22 does make more torque, but at low/partial throttle the 3.73's do much better than the 3.42's did in a gear lower even thou on paper the 3.42' in a lower gear had the mechanical advantage on paper.

 

[timelinex]

@timelinex peak torque is not at/near redline but peak hp is.

SO/HO peak horsepower is at 2800 rpms
SO peak torque is at 1700 rpms
HO peak torque is at 1800 rpms

Torque curves are no longer relatively flat on these trucks. 1075lb/ft at 2800 rpms would be 573hp.

Going from my 18 with 3.42's to my 22 with 3.73's I can tell you that there is a huge difference just from the gearing. The 22 does make more torque, but at low/partial throttle the 3.73's do much better than the 3.42's did in a gear lower even thou on paper the 3.42' in a lower gear had the mechanical advantage on paper.

Got it.

Then I may have mixed up torque and HP. The rest of my analysis should be right but with the words HP substituted in for torque. It should be the same otherwise. HP must be what is pulling the weight at 60mph up a hill. Otherwise, we could just shift UP to put it at 1800 and have it start pulling hard. We all know that isn't how it works! haha

As a metaphor...There is absolutely no inherent speed advantage to different gearing in a bicycle. As an athlete, you have a pedaling cadence that is most preferred (the hardest you could pedal without getting excess fatigue). That would align with a vehicle's peak HP. The gears are just there to ensure you can keep that perfect cadence regardless of your speed.

 

[AH64ID]

Got it.

Then I may have mixed up torque and HP. The rest of my analysis should be right but with the words HP substituted in for torque. It should be the same otherwise. HP must be what is pulling the weight at 60mph up a hill. Otherwise, we could just shift UP to put it at 1800 and have it start pulling hard. We all know that isn't how it works! haha

Basically, torque is how much work you can get done and horsepower is how fast you can do that work. Torque doesn't have time associated with it's measurement, only horsepower does.

So you can have a 10,000 lb/ft motor do all kinds of work but if it has 1 hp (0.5rpms) it's not going to do it very fast, but if it has 10,000 hp (5252 rpms) it will do it fast.

Another example is a turbine engine. I work with engines that standard peak output is 1407hp and 354 ft-lbs, but that's at 20,900 rpms which is not a lot of work but very fast, but by the time it's geared down to 258 rpms that 354 ft-lbs is 28,676 (not counting accessory systems losses) were not doing a LOT of work pretty darn fast.. and that's a single engine on a dual engine platform.

 

[Dave01]

No one said 3.73 would tow better, the argument is that the 3.73 tows well enough in nearly all driving conditions that the 4.10 is not necessary with paired with the HO and aisin. The aisin is a 6-speed, not 8-speed. And it has a very deep first gear to help with take off (can stay in first gear and in the power band longer with the 3.73 than the 4.10).

I'm aware the Aisin is 6 speed, and you're right to point it out, I should have been more clear in my post. I don't agree with your 1st gear analysis, but I'm certainly no expert.

What I do believe is that if Ram didn't offer the 3.73, only the 4.10, I don't think we'd see many, if any, owners posting that "I really wish they offered 3.73". I suppose for those few that feel the 1/2 mpg or so is important, but other than that everyone would be happy they had 4.10's. Not to mention that a decent % of owners go with bigger than stock wheels.

 

[timelinex]

I'm aware the Aisin is 6 speed, and you're right to point it out, I should have been more clear in my post. I don't agree with your 1st gear analysis, but I'm certainly no expert.

What I do believe is that if Ram didn't offer the 3.73, only the 4.10, I don't think we'd see many, if any, owners posting that "I really wish they offered 3.73". I suppose for those few that feel the 1/2 mpg or so is important, but other than that everyone would be happy they had 4.10's. Not to mention that a decent % of owners go with bigger than stock wheels.

Can't this sentiment be explained by my point #2:

Passing at various speeds. Since the gears are "shorter", you are more likely find a gear you can downshift to that puts you near peak torque, regardless of speed. I think this phenomenon is probably the reason people are adamant about 4.10's feeling faster during higher gears as well. Anytime you floor it, there is a bigger chance you will land into the top portion of your torque curve.

People feel the 4.10 pulls weight better because you can get into the peak power production more often. In most scenario's there will be no palpable difference, but when you need power to pass and don't have it, you remember it. Like in my example, 48mph is obviously a bad spot for the 3.73's, where as in the 4.1 I likely wouldn't have had the issue. So a 4.10 IS, on average, going to pull the weight better. I think the argument is that it's mostly around the edges.

I know you weren't replying to me directly, but I was looking to see how 4.10's could have helped me with my primary complaint:

When I'm at almost 60mph and it won' go any faster I am nearing redline. Which means I am basically right at peak [power] as it is. A 4.10 can't help that. I'm already laying as much moving force onto the ground as my engine can provide. The multiplier doesn't change that. In fact, 3.73's may be the perfect gearing for my situation since I'm already in peak [power].

 

[darrellr]

Can't this sentiment be explained by my point #2:



People feel the 4.10 pulls weight better because you can get into the peak power production more often. In most scenario's there will be no palpable difference, but when you need power to pass and don't have it, you remember it. Like in my example, 48mph is obviously a bad spot for the 3.73's, where as in the 4.1 I likely wouldn't have had the issue. So a 4.10 IS, on average, going to pull the weight better. I think the argument is that it's mostly around the edges.

I know you weren't replying to me directly, but I was looking to see how 4.10's could have helped me with my primary complaint:

In your example, you could have locked the transmission into a lower gear (I know I can, not sure what packages may or may not have that feature) rather than waiting for it to downshift itself, which sounds like never happened. That would have put you further into your torque and hp curves. Sure, a 4.10 rear end may have alleviated the need to do that step, but you said it happened once. Enjoy the mileage. Even if only .5 mpg, at 7.5mpg I get towing .5 is not an insignificant number.

 

[56ram2500]

Being you all want to compare different gearing, the best example I can use to help others understand the difference in the gearing is from my trucking days hauling 80K in the hills with real life experience… The company I worked for had 3 trucks all same year of manufacturing, all with the same engine 350 Cummins, all 3 had the same 13 speed road ranger transmission, but they all had different gearing, one had 390, one had 411 and the other had 488, based on the 3 of one summer racing up Mt Shasta on I-5 I can tell you the truck with 488 ate the lunch of both the 411 and 390 to the top of Mt Shasta, the 411 was behind the 488 in hill climbing but it was also in front of the truck with 390, thus gearing make a big difference while towing in the mountains….

 

[darrellr]

I am pretty sure everyone here knows that shorter gears will pull better. The question is more about what better really means in the realm most of us are towing in. And is that situation occurring often enough to warrant having the shorter gears all the time. As others have stated, it is really a decision made based on where folks are towing, how frequently they tow, how heavy they tow, and even how often they tow in mountains versus hills or flat land. How important to them is saving 5mph going up an 8% grade twice in a trip across country? A 7% hit to fuel mileage during the rest of the trip is worth way more impactful to me than rolling up a hill 5mph slower once or twice. But I guarantee you will not find a highway that my 3.73 will not tow my 21k trailer up at near speed limit runs unless something else was causing the slowdown. It won't come from the engine, transmission, transfer case, or rear differential.

 

[AH64ID]

I am pretty sure everyone here knows that taller gears will pull better.

Complete opposite. Shorter gears, 4.10 for Ram, will pull better.

 

[Rockcrawlindude]

Guys it’s math. Rear end gear matters. Doesn’t matter if you include the transmission or not.

You can do
4.10:1 / 3.73.1 = 1.099 or 9.9% difference
Or
You can do (using 3.75 HO aisin 1st)
3.75 1st gear x 4.10 = 15.375:1
3.75 1st gear x 3.73 = 13.9875:1
15.375:1 / 13.9875:1 = 1.099 or 9.9% difference.

4.10s are about 10% better at moving a heavy load than 3.73s.

Does it matter when you have 1000lb/ft? Are you near max tow?

Just put it in tow haul, slow down and pull the trailer.