Low speed loaded test of 3.42....

[Cummins12V98]

Not sure about that Ron, the on ramp run we did in your truck with all four of us in the truck was pretty impressive.

We will have to give it a go!

 

[dieselshadow]

It doesn't matter whether it is AT speed or getting TO speed, final drive ratio does not take into account the extra load imposed by the lower numerical ratios. It doesn't matter whether it is steady state or accelerating the effort required remains the same in each state and the diff ratio will effect that more than anything else. It will take more effort to roll a given load at a given speed with 3.42's than it will with 4.10's. All things being equal, that can be documented by engine load.

I beg to differ sir.

The final drive ratios are virtually the same with 5th gear and 4:42s and 6th gear and 4:10s as mentioned many times here. The final drive ratio is what determines the overall load (that and the load itself). So if the final drive ratio is the same at speed how would the engine load be different?

I totally agree with you about accelerating from a standstill. But at speed, not so much. The one example is 5th gear towing simply negating the 6th. I personally chose a truck with the gearing to fit my purpose and potential loads and utilize all the gears as designed, but I get the workaround.

I kinda like to see these 8-10 speed transmissions come to the Cummins/Ram trucks. We would greatly benefit from it. Higher ratios in the differential and high speed empty economy without losing towing capacity.

 

[SnoKing]

Higher ratios in the differential and high speed empty economy without losing towing capacity.

Gee, I feel I already have that. SnoKing

 

[dieselshadow]

Gee, I feel I already have that. SnoKing

You don’t.

Seriously, a truck with 4:10s will out tow a 3:42 any day of the week. Doesn’t mean you can’t, but when it comes to towing, the 4:10 is king right now. That’s been discussed several times as to why in this thread.

 

[Cummins12V98]

You don’t.

Seriously, a truck with 4:10s will out tow a 3:42 any day of the week. Doesn’t mean you can’t, but when it comes to towing, the 4:10 is king right now. That’s been discussed several times as to why in this thread.

Depends.

I get on the freeway once then drive at freeway speeds for hours then stop. How much of that time did I use anything other than 6th with my 4.10’s or with my 3.42’s 5th?

See my point???

Takes 10 seconds longer to get on the freeway really matter?

 

[Cummins12V98]

You don’t.

Seriously, a truck with 4:10s will out tow a 3:42 any day of the week. Doesn’t mean you can’t, but when it comes to towing, the 4:10 is king right now. That’s been discussed several times as to why in this thread.

Depends.

I get on the freeway once then drive at freeway speeds for hours then stop. How much of that time did I use anything other than 6th with my 4.10’s or with my 3.42’s 5th?

See my point???

Takes 10 seconds longer to get on the freeway really matter?

 

[DeansRedRam]

My Sons SRW runs 35’s with AISIN no issues at 125k or so.

Good to hear. I know it won't be an issue, but I know for sure I will notice and will miss how the truck drove on a stock platform, i.e. acceleration, rpms at speeds, and towing.

 

[dieselshadow]

I get on the freeway once then drive at freeway speeds for hours then stop. How much of that time did I use anything other than 6th with my 4.10’s or with my 3.42’s 5th?
Takes 10 seconds longer to get on the freeway really matter?

Again, a 4:10 truck will out accelerate and pull a larger load than a 3:42. Flat and steady towing isn’t a real world luxury many people get to experience. So yes, in the world of towing, it does matter. Hence the appropriate tow ratings for differently geared trucks. ...as stated before...

Facts are facts. Just because it works for you, and I’m not saying or arguing that it doesn’t, doesn’t mean it’s not true. Basically your “butt meter” or “happiness factor” doesn’t mean virtually all manufacturers and engineers with all these designed tests and specs are completely wrong.

BTW, I get your logic and reasoning for choosing your rig, I’m in no way condemning your choice or saying you made a mistake. I’m glad it works out well for you. Sometimes I wonder if I should’ve done the same. But at the end of the day, I’m willing to pay for the slight mileage loss for my gearing choice compared to the higher ratio. I don’t use it for a ton of miles and I’d prefer the power and performance when needed the 4:10s provide.

 

[SnoKing]

Based on the tow ratings on my 2015 RAM the 3.42's handle the load just fine. I towed just fine at 24,500 lbs combined. The higher ratings of the newer SRW trucks can not be met without exceeding the RGAWR in most cases, so they are more or less worthless.

 

[SnoKing]

Funny, 3.42's worked fine from 2013 models to 2018? Why are they now a problem.

 

[dieselshadow]

Funny, 3.42's worked fine from 2013 models to 2018? Why are they now a problem.

Who claimed a problem? I don’t recall reading that in this thread?

 

[cerberusiam]

The final drive ratios are virtually the same with 5th gear and 4:42s and 6th gear and 4:10s as mentioned many times here. The final drive ratio is what determines the overall load (that and the load itself). So if the final drive ratio is the same at speed how would the engine load be different?

Because the final drive ratio is just a number that ignores the pertinent factors. Engine load is not dependent on final drive ratio it is dependent on the effort needed to transfer the power to the ground and "do the work". What every discussion so far refuses to acknowledge is the "do the work" factor, it cannot be ignored as it is integral to the discussion.

Simply cannot have it both ways and just "lose" energy, the physical world simply does not work that way. If you acknowledge the fact that a 4.10 geared truck will out accelerate a 3.42 geared truck under the SAME load you are by default acknowledging the former will need less engine load to maintain a set speed than the latter. It is all about time and distance, any gear ratios involved just modify or are used to modify the basic unit of work, time and distance.

There is a misconception that the OD ratios impart a mechanical advantage, it doesn't. It reduces the mechanical advantage. When you reduce the mechanical advantage and reduce the leverage how can the efficacy in any shape or form be better? Short answer is it can't, but if the SOP meter can't measure it doesn't know that so opinions are touted as fact.

 

[JR]

I wonder, though, if that would be the case if the Aisin was offered in the 2500, even if behind the SO engine?

Tom, all I can tell you is my personal experience of buying used, which spanned casual looking for close to two years and aggressively seeking for 6-8 months. I don't know the ratio but the 68 was in most 3500s I looked at, both online And in person. You'd be surprised how many guys didn't even know which trans they had. "It's an automatic behind that big Cummings engine!". Ok! Thanks!
I think most just don't care, and would either rather spend the $3k or whatever the upcharge is on bells and whistles or simply save the money.

 

[dieselshadow]

Because the final drive ratio is just a number that ignores the pertinent factors. Engine load is not dependent on final drive ratio it is dependent on the effort needed to transfer the power to the ground and "do the work". What every discussion so far refuses to acknowledge is the "do the work" factor, it cannot be ignored as it is integral to the discussion.

Simply cannot have it both ways and just "lose" energy, the physical world simply does not work that way. If you acknowledge the fact that a 4.10 geared truck will out accelerate a 3.42 geared truck under the SAME load you are by default acknowledging the former will need less engine load to maintain a set speed than the latter. It is all about time and distance, any gear ratios involved just modify or are used to modify the basic unit of work, time and distance.

There is a misconception that the OD ratios impart a mechanical advantage, it doesn't. It reduces the mechanical advantage. When you reduce the mechanical advantage and reduce the leverage how can the efficacy in any shape or form be better? Short answer is it can't, but if the SOP meter can't measure it doesn't know that so opinions are touted as fact.

So you’re saying 2.58 isn’t pretty darn close to 2:63? One truck would be spinning the driveshaft faster than the other, that’s it. The load isn’t driveshaft speed, it’s the overall resistance to being moved down the road.

Please explain to me how the final drive ratio has no effect to engine load, but differential ratio does?

Tire size (overall diameter) effects final drive ratio and the overall engine load. But tire size doesn’t effect differential ratio. According to your statement, I could put whatever tire I wanted on anything and it would have zero effect on the truck. We all know that’s not true.

 

[SnoKing]

There is a misconception that the OD ratios impart a mechanical advantage, it doesn't. It reduces the mechanical advantage. When you reduce the mechanical advantage and reduce the leverage how can the efficacy in any shape or form be better? Short answer is it can't, but if the SOP meter can't measure it doesn't know that so opinions are touted as fact.

That is the exact issue we are making. The 3.42 truck running in 5th has a slightly lower final drive ratio than the 4.10 truck in 6th gear. If a lower gear diff increasing the ability to do work, the same applies to a lower transmission gear ratio. The Aisin first gear is almost un-needed about 90% of the time in the 4.10 truck in normal driving. Some have wished for a second gear start option.

 

[kthaxton]

Just to simplify things....is there anyone here that thinks a higher (numerically lower) gear ratio will move a heavy load better than a low gear ratio? Forget about compromises to suit anyone's specific needs, unloaded mileage etc etc, but anyone NOT agree with the mechanical advantage that lower gears provide?

What about how lower gears ease the load on all drivetrain components ahead of those gears? Anyone disagree with that?

I agree that the engine doesn't know, feel, or care where the gear reduction comes from in a 5th gear 3.42 vs. 6th gear 4.10's scenario, but the transmission and driveline do in regards to the load it sees. With 5th gear and 3.42's all of the components of the trans after the gear reduction (any clutches, shafts, gears) and the driveline/u-joints are all seeing more load than 6th gear with 4.10's. Not that it can handle this, but it is slightly more wear.
We already discussed the sacrifices of losing 6th gear while towing and not have as low of a 1st gear.

The point I want to make is that if you want to move a heavy load, and moving that load well is the top priority:
3.42 Good
3.73 Better
4.10 Best

In each of the 6 gears, you will have more torque, more mechanical advantage available with a lower R&P ratio vs a higher one and that advantage comes from the increased leverage of the gears themselves.

If I went from my 3.42's to 3.73's, each of my transmission gears would be more useful while towing. 6th would have more torque than now, 5th would have more torque etc. etc. This means 6th would be more usable, 5th would be more usable and so on down the line.

 

[SnoKing]

Just to simplify things....is there anyone here that thinks a higher (numerically lower) gear ratio will move a heavy load better than a low gear ratio? Forget about compromises to suit anyone's specific needs, unloaded mileage etc etc, but anyone NOT agree with the mechanical advantage that lower gears provide?

What about how lower gears ease the load on all drivetrain components ahead of those gears? Anyone disagree with that?

I agree that the engine doesn't know, feel, or care where the gear reduction comes from in a 5th gear 3.42 vs. 6th gear 4.10's scenario, but the transmission and driveline do in regards to the load it sees. With 5th gear and 3.42's all of the components of the trans after the gear reduction (any clutches, shafts, gears) and the driveline/u-joints are all seeing more load than 6th gear with 4.10's. Not that it can handle this, but it is slightly more wear.
We already discussed the sacrifices of losing 6th gear while towing and not have as low of a 1st gear.

The point I want to make is that if you want to move a heavy load, and moving that load well is the top priority:
3.42 Good
3.73 Better
4.10 Best

In each of the 6 gears, you will have more torque, more mechanical advantage available with a lower R&P ratio vs a higher one and that advantage comes from the increased leverage of the gears themselves.

If I went from my 3.42's to 3.73's, each of my transmission gears would be more useful while towing. 6th would have more torque than now, 5th would have more torque etc. etc. This means 6th would be more usable, 5th would be more usable and so on down the line.

Yet, the 2013-2018 SRW Aisin trucks do just fine up to their rate capacity with 3.42 gears. Where is the problem? And as a bonus they get very good mileage out on the open road. I learn that in the first 48 hours on ownership flying across Wyoming and Eastern Idaho at 80 MPH at 1750 RPM's and 19 MPG. Then I towed a 16K high profile 39'4" 5th wheel in Arizona and back twice at 24,500 combined weight and again it did just fine. I would not trade my 3.42 gears, even if the change was free!

As far on the drive line etc. The 3.42 diff pinion gear is more robust than the 4.10 one. Regarding 6th gear and towing with 4.10, you are putting more stress on a double OD gear.

Continuing to beating a dead horse does not make it more dead!

 

[kthaxton]

Yet, the 2013-2018 SRW Aisin trucks do just fine up to their rate capacity with 3.42 gears.

Doing "fine" and what is optimum are two different things. I think I qualified my statements about ultimate goals.

Continuing to beating a dead horse does not make it more dead!

Is it only everyone else that is beating a dead horse, and not you?

 

[cerberusiam]

If a lower gear diff increasing the ability to do work, the same applies to a lower transmission gear ratio.

No, it does not apply equally. Transmission gearing changes and tire sizes modify the leverage at the R&P, they cannot significantly change it. You are correct in that you would see a small change with a gear change, but, an R&P change would be a major change in observed load.

So you’re saying 2.58 isn’t pretty darn close to 2:63? One truck would be spinning the driveshaft faster than the other, that’s it. The load isn’t driveshaft speed, it’s the overall resistance to being moved down the road.

That is 5 HUNDREDTHS difference, but of WHAT? All you are doing is comparing 2 numbers with nothing to APPLY then to. As you say it is the resistance to movement that generates the load. That is directly rates to the leverage to overcome the resistance. The leverage point that has the most impact will still be the diff gearing. Discarding all the OD ratios and such think 1:1 thru the trans and compare 3.4 to 4.1 ratios, which one has the better leverage. Trans gear ratio just modify that main leverage ratio in smaller increments.

Please explain to me how the final drive ratio has no effect to engine load, but differential ratio does?

I never said that so it isn't a question I can answer.

Tire size (overall diameter) effects final drive ratio and the overall engine load. But tire size doesn’t effect differential ratio. According to your statement, I could put whatever tire I wanted on anything and it would have zero effect on the truck. We all know that’s not true.

I never said that either so not something I can solve for you.

 

[SnoKing]

Doing "fine" and what is optimum are two different things. I think I qualified my statements about ultimate goals.



Is it only everyone else that is beating a dead horse, and not you?

My horse is up on all four running around just fine! 65K in 4.5 years. Has towed heavy, been in very strong winds towing heavy, has had recalls and a code once that never came back after the SCR recall. Loves to stretch her legs out on the open road. I said "her" as truck was named Cherry for the deep cherry crystal color.