6.4L Hemi vs 7.3L Ford Gasser-either in a Dually

[ramffml]

You obviously don't understand how rear end gearing works. Every single gear of the transmission is affected by the rear end gear. 6th is lower going through a 4.30 rear than a 3.73 rear, 4th is too, so is 1-10. All gears benefit from the lower 4.30 rear end gear.

Glad I could clear that up for you.

Your mistake (very common) is in thinking that the truck will be using the same gear number for a given speed, that it used to before the change. It won't. Gear shifts are driven by load and rpm.

So if you used to climb a hill in 4th with the 3.73, at 2000 rpms, after the swap to 4.30 your truck might take that same hill in 5th at approx 2000 rpms. You gained nothing, all you did was change what transmission gear number your using to perform the work.

Imagine your truck rear end was very "high end" and could be shifted from a 2.50 to 3.10 to 3.50 to 4.10 to 4.30. Wouldn't that be cool, you can pick whatever gear in the back you need? But that is exactly what your tranmission does. 10 gears is impressively cool, you don't need to worry about rear end at that point because your transmission will downshift to whatever gear you need, to make sure your RPMs are just high enough to make enough power to handle the current load.

 

[GonnaBuyaDually]

Your mistake (very common) is in thinking that the truck will be using the same gear number for a given speed, that it used to before the change. It won't. Gear shifts are driven by load and rpm.

So if you used to climb a hill in 4th with the 3.73, at 2000 rpms, after the swap to 4.30 your truck might take that same hill in 5th at approx 2000 rpms. You gained nothing, all you did was change what transmission gear number your using to perform the work.

Imagine your truck rear end was very "high end" and could be shifted from a 2.50 to 3.10 to 3.50 to 4.10 to 4.30. Wouldn't that be cool, you can pick whatever gear in the back you need? But that is exactly what your tranmission does. 10 gears is impressively cool, you don't need to worry about rear end at that point because your transmission will downshift to whatever gear you need, to make sure your RPMs are just high enough to make enough power to handle the current load.

I made no mistake at all. What I said was 100% factual. You seem to be stuck on a few things. Using a 250 word salad to justify your misunderstanding of me showing you numerically where you erred is not a valid response.

Any gear selected, when going through a lower rear end gearing (higher numerically) will have a lower overall gear ratio. Therefore the engine will have more torque multiplication in every gear. Your example is extremely flawed because using a higher transmission gear (up to 1:1, where towing is typically done) to go through a lower rear end gear to maintain the "rpm" that you 'think' an engine wants to maintain will always give the engine better response and allow for more leverage and the ability to downshift into another gear.

In every towing gear, the 4.30 offers better leverage for the engine:



If that's hard for you to understand, then the simple explanation is that lower rear end gears make towing easier. Period.

 

[sandawilliams]

The older heavy duty trucks ( 1.5 tons and larger) had two speed rearends. You could change the rear gearing with a vacuum shifter attached to the 4 speed manual. Rear end gearing is what dictated torque vs. speed on these trucks. Without the rear axle gear selection you would be limited to low gearing for loads or high gearing for speed. Point is rear gearing does dictate how versatile a vehicle can be.

 

[ramffml]

I made no mistake at all. What I said was 100% factual. You seem to be stuck on a few things. Using a 250 word salad to justify your misunderstanding of me showing you numerically where you erred is not a valid response.

Any gear selected, when going through a lower rear end gearing (higher numerically) will have a lower overall gear ratio. Therefore the engine will have more torque multiplication in every gear. Your example is extremely flawed because using a higher transmission gear (up to 1:1, where towing is typically done) to go through a lower rear end gear to maintain the "rpm" that you 'think' an engine wants to maintain will always give the engine better response and allow for more leverage and the ability to downshift into another gear.

In every towing gear, the 4.30 offers better leverage for the engine:


If that's hard for you to understand, then the simple explanation is that lower rear end gears make towing easier. Period.

I love the red chicken scratching, lol.

You're getting stuck on the fact that the 4.10 DOES offer more torque in the same transmission gear, than say a 3.73.

What you're MISSING, is that they won't use the same gear at the same time anymore. The 4.10 will upshift quicker from first than the 3.37 will, so most of the time at any given speed, the 4.10 will be in a higher numerical gear in the transmission than the 3.73 will be, thus it will lose the torque advantage again.

From a stop: both trucks accelerate, the 4.10 will shift into 2nd gear (at say 15 mph), but the 3.73 will hold first until (say) 20 mph. So at 15 mph, the 4.10 is in second, the 3.73 is still in first, who is making more power at that point?

Same thing at other times. When the 4.10 is towing up a hill in 6th, at 50 mph, the 3.73 is not FORCED to be also in 6th. It can be in 5th, making MORE power than the 4.10. It can also be in 4th, making even MORE power.

So stop thinking the 4.10 and 3.73 absolutely need to be in the same gear at the same time for every scenario. Transmissions can downshift, and when they do, the torque advantage is available for them at lower gears.

The ONLY time the 4.10 has a real torque advantage that cannot be matched by the 3.73, is when both trucks are in first gear. As long as the 3.73 has room to downshift, there is no torque advantage.

And with 10 gears available to choose from, there is a final gear ratio available for every scenario and every load and every speed. We're no long driving 3 and 4 speeds where rear end is incredibly important, the transmissions do this for us now.

 

[Tim7139]

Yes, a properly equipped 3500 dually gasser can pull 15-20k, but how effectively and more importantly, how safely?

This is why modern trucks have SAE tow rating, to test and verify what can be pulled safely.

 

[HEMIMANN]

The older heavy duty trucks ( 1.5 tons and larger) had two speed rearends. You could change the rear gearing with a vacuum shifter attached to the 4 speed manual. Rear end gearing is what dictated torque vs. speed on these trucks. Without the rear axle gear selection you would be limited to low gearing for loads or high gearing for speed. Point is rear gearing does dictate how versatile a vehicle can be.

I think @ramffml 's point is it doesn't matter much now with almost infinitely variable speed transmissions. Back in the old days of 3 or 4 speed transmissions it did, yes.

Btw, I drove an old Ford F700 1.5 ton dump bed for a landscape service in the late 70's. It had a gas motor that was a dog. It also had the split rear axle that you HAD to run in high ratio when hauling heavy (dirt), or the thing couldn't even climb a hill! I'd annoy everybody behind me on 2 lane roads!

 

[retired]

I will take the higher numerical rear end gear ratio any day whether in a 6, 8 or 10 speed. If Ram made a 4.30 instead of 4.10 I would go that route. no matter how many gears you have the higher numerical rear end keeps the tranny from searching for gears. I have driven Ram 3500 6.4 with 8speed with both 3.73 and 4.10's and in the terrain I drive in ie Montana where you are either going up or going down the 4.10's feel better and that is when not pulling anything. Makes even more of a difference when you start going up to 35, 37's and 40's etc. Sure a tranny get be shifting up and down but I like setting the cruise at 70-85mph and not have my tranny constantly shifting down...We all have different seat of the pants tho. Here is one thing I do know comparing my buddy's 7.3 with 4.30 10 speed to my 6.4 with 4.10 8 speed is not a fair comparison, it leaves me feeling sad and blue lol....RAM needs to get with it.

 

[GonnaBuyaDually]

I think @ramffml 's point is it doesn't matter much now with almost infinitely variable speed transmissions. Back in the old days of 3 or 4 speed transmissions it did, yes.

Btw, I drove an old Ford F700 1.5 ton dump bed for a landscape service in the late 70's. It had a gas motor that was a dog. It also had the split rear axle that you HAD to run in high ratio when hauling heavy (dirt), or the thing couldn't even climb a hill! I'd annoy everybody behind me on 2 lane roads!

But there is nothing even close to infinitely variable speed transmissions in these super duties. There are 3 overdrives, none of which should he used for heavy towing on hilly terrain. What you have with a ten speed is 7 gears to get to 1:1. The lower rear end is absolutely a benefit for every single gear, overdrives included, when towing. It does matter in today's gas engine.

What rammfl refuses to acknowledge is that he is absolutely wrong, and that having a lower rear end helps a gas engine stay in it's narrow (with respect to a diesel engine) power band and manage all towing tasks more easily. It's to the point that he has lost any shred of credibility regarding this conversation.

 

[GonnaBuyaDually]

I love the red chicken scratching, lol.

You're getting stuck on the fact that the 4.10 DOES offer more torque in the same transmission gear, than say a 3.73.

What you're MISSING, is that they won't use the same gear at the same time anymore. The 4.10 will upshift quicker from first than the 3.37 will, so most of the time at any given speed, the 4.10 will be in a higher numerical gear in the transmission than the 3.73 will be, thus it will lose the torque advantage again.

From a stop: both trucks accelerate, the 4.10 will shift into 2nd gear (at say 15 mph), but the 3.73 will hold first until (say) 20 mph. So at 15 mph, the 4.10 is in second, the 3.73 is still in first, who is making more power at that point?

Same thing at other times. When the 4.10 is towing up a hill in 6th, at 50 mph, the 3.73 is not FORCED to be also in 6th. It can be in 5th, making MORE power than the 4.10. It can also be in 4th, making even MORE power.

So stop thinking the 4.10 and 3.73 absolutely need to be in the same gear at the same time for every scenario. Transmissions can downshift, and when they do, the torque advantage is available for them at lower gears.

The ONLY time the 4.10 has a real torque advantage that cannot be matched by the 3.73, is when both trucks are in first gear. As long as the 3.73 has room to downshift, there is no torque advantage.

And with 10 gears available to choose from, there is a final gear ratio available for every scenario and every load and every speed. We're no long driving 3 and 4 speeds where rear end is incredibly important, the transmissions do this for us now.

I'm not thinking that, and I'm not missing anything at all, you are. The "red chicken scratching" clearly lays out the gearing advantage of having a 430 vs a 373. The 430 has 5 gears to get to a final drive ratio of 5.8 vs 3 gears for the truck that has the 373. That means the truck with more gears will have more ability to be in the narrow power band that exists for its gas engine, which means better towing performance.

I just chose to look at the 5.8 ratio because they both share that ratio exactly, and maybe it makes it more remedial for you to understand what is happening.

I know you think you understand it but you really don't. You need to lose your ego and take a minute to realize that you might not understand everything there is to know about rear end gearing, and take this opportunity to learn what you don't currently understand.

 

[huntergreen]

Hello. Looking for real world comparisons of these two drivetrains. I have had the 8 speed, so I know it is absolutely the bee's knee's, but, I am enamored with the higher output of the 7.3L Ford. I think the Ford 10 speed has a lot of promise, but I am not convinced that it is on par with the 8 speed. Same situation, but in reverse on the engines. I have a 5.7L hemi that has given me good service, but the 6.4L seems to be derated for the trucks. Why? The 485HP that they make in the SRT vehicles would do a lot to persuade me toward a Ram, but the 6.4L in the trucks only has 410hp. I looked at the torque curves of each 6.4L engine, and there are no answers there either. The higher horsepower SRT version makes great torque down low.

I am going to buy a 350/3500 dually crew cab long bed truck. I already put a deposit down on a Ford. I am getting very shakey about it though, as there is report after report about rear end/transmission noise and several people have posted pictures of low mileage trucks with metal contaminated rear end oil. Numerous people are saying that there is a grinding noise when shifting from 5-4 or 5-3 or 4-3 while slowing down. No one has pinpointed where this is coming from, there are NUMEROUS trucks that have already been back in to the dealer for this noise and several have been advised that new rear ends are needed. This is in ADDITION to a M275 Dana Axle recall that Ford already has underway due to thin castings at the spring mount.

I know my Jeep had DANA axles, do these Ram 3500 4.10 rears have Dana axles? I know that Dana typically makes excellent axles, but you can forgive me for being very cautious about this issue. There are already active recalls in place, and now there are numerous verified issues that Ford has NOT addressed.

I've had great luck with the prior 4 Chrysler/Jeep purchases that we've made, and I'm considering a fifth now.

This truck will be used primarily to tow 16-20,000lbs of tractor around a radius of about 70 miles of foothills at speeds of no more than 65mph.

Please comment as you feel necessary. Thanks.

I’ve read this complete thread, weather you buy Ford or Ram is up to you, but IMHO, I believe you would be better off with the diesel. The 7.3 gasser is new and untested, and to me that’s too much for weight for the 6.4. I’m partial to the Cummins, but that is just me. Good luck with whatever you decided.

 

[ramffml]

I'm not thinking that, and I'm not missing anything at all, you are. The "red chicken scratching" clearly lays out the gearing advantage of having a 430 vs a 373. The 430 has 5 gears to get to a final drive ratio of 5.8 vs 3 gears for the truck that has the 373. That means the truck with more gears will have more ability to be in the narrow power band that exists for its gas engine, which means better towing performance.

I just chose to look at the 5.8 ratio because they both share that ratio exactly, and maybe it makes it more remedial for you to understand what is happening.

I know you think you understand it but you really don't. You need to lose your ego and take a minute to realize that you might not understand everything there is to know about rear end gearing, and take this opportunity to learn what you don't currently understand.

We're talking about 8 and 10 speeds here. Rear end is a complete non issue, there is a difference of a few hundred rpms between each gear so there is literally an rpm/gear for every scenario. I'm sorry that you can't understand this but I'm not going to beat myself up trying to convince you either. You think what you like.