3.73 vs 4.10 Advice Please!

[Texas Ted]

I am looking to buy a 6. 7 w/6 spd auto, 4x2, 350 DRW pickup, long bed. I'll be towing 14,000lbs, most of the time in the west, long grades. I would like to stay within the 23,000 gcwr rating of the 4. 10. The rating of the 3. 73 is 21,000 gcwr. The truck will also carry the usual load of toolbox, aux tank etc.

Does anyone know what the engine rpm for the 4. 10 is at say 60mph?



How about the 3. 73 at the same 60mph?



Has anyone had experience towing heavy with either of these two ratios?



I don't find the basic empty weight of the truck listed anywhere either.



Any experiences or advice would be appreciated.

Thanks, Ted

 

[jcarey]

Try looking here:



http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls





Very nice job!

 

[CUMMINZ]

Tttttttttttttt

My 4. 10 runs 1850 @ 70mph. Go with the 4. 10s. The guys with the 3. 73s don't know what they are missin':-laf My 06' with 4. 10s @ 70 ran 2200.



My 07. 5 is 4600 front 3560 rear with lightly loaded tool box and 5er hitch and full of fuel. Total 8160

 

[MRosinski]

I second the 4. 10's. The new 6spd auto brings the rpm's down to a perfect towing or unloaded range.

 

[Texas Ted]

Thanks for all the input here. I was concerned about the 4. 10's running at a high rpm. My old 93 runs at 2200 rpm @ 65. Not comfortable for any solo driving. That's wound up pretty good.



Sounds as though the 4. 10 on the new truck should not sacrifice much on mileage if the rpm runs at 1850 @ 70. Especially if towing heavy.



I appreciate the help on the weights as well.

ANY OTHER COMMENTS WELCOME.

Ted

 

[Texas Ted]

Thanks, jcarey, for the tip on the Excel Chart by Klenger Dodge. Thats a good one for everyone to pick up on.

Ted

 

[Sky]

My 4. 10 runs 1850 @ 70mph. Go with the 4. 10s. The guys with the 3. 73s don't know what they are missin':-laf My 06' with 4. 10s @ 70 ran 2200.

Boy I wish I knew that before I ordered mine with the 3. 73's. 4:10's sound like the way to go...

 

[DSpivey]

Boy I wish I knew that before I ordered mine with the 3. 73's. 4:10's sound like the way to go... [/Q



me too. but mine still runs at 1700 at 70 with the 3. 73 4. 10 just 150 more rpms. will that little of a rpms diff make that big of a diff . if so i might consider changing out.

 

[TKeeler]

I am looking to buy a 6. 7 w/6 spd auto, 4x2, 350 DRW pickup, long bed. I'll be towing 14,000lbs, most of the time in the west, long grades. I would like to stay within the 23,000 gcwr rating of the 4. 10. The rating of the 3. 73 is 21,000 gcwr. The truck will also carry the usual load of toolbox, aux tank etc.

Does anyone know what the engine rpm for the 4. 10 is at say 60mph?



How about the 3. 73 at the same 60mph?



Has anyone had experience towing heavy with either of these two ratios?



I don't find the basic empty weight of the truck listed anywhere either.



Any experiences or advice would be appreciated.

Thanks, Ted

I personally like the 4. 10's... if I want to bump up the tire size a bit I still got good take off torque and the 4. 10's go plenty fast for me. 60mph is right at 1,700 RPM with everything stock.

 

[CUMMINZ]

I ordered 4. 10s with my 04. 5 knowing I was going to put 315s on it and I loved that gearing. I plan to put 19. 5sx 245 on this 07. 5... That will bump me down just a touch.



This 68rfe is great... It has low gear lower than the 48re and 2 gears over the 4th. direct drive. DC done good...



Back in the day that early cummins had half the HP and TQ and they would not pull you out of a ditch compaired to what we have now gears made much more difference. Today with higher rpms it is not as necessary to run low gear numbers. My DCs since 04. 5 with 4. 10s love the 2200-2300 range with milages matching 3. 73s.



This debate could go on forever just like the "who has the best transmission".

 

[jcarey]

Peak torque is @1500 RPM on the 6. 7L, so I don't see the need/value for the extra 150 RPMs



From Cummins:

Engine..... Advertised..... Peak Torque... Governed

Model... ... hp @ rpm... ... . lb-ft @ rpm..... Speed



6. 7-Liter. . 350 @ 3013... 650 @ 1500... 3013

 

[CUMMINZ]

Jc

You are missing the point. The 6. 7L does not exactly reach "peak" at 1500 and to say that is it's best towing or pulling rpm. It actually has a reasonably flat peak torque range from 1500 - 2900rpms. The 4. 10 gears ALWAYS will handle a load better in ALL gears than will a 3. 73. I had heard some say I'll just downshift one gear and still do just as good as a 4. 10. No way. Launches are better, shifting is better, more HP is applied to the ground better and more efficiently. Your rig will buck a head wind better and have less effect on your rig. Your sweet spot is never 1500rpms. Hit the bottom of a 10% grade at 1500rpms with a GCVW of 26k vs. 1900-2200rpms and see the difference. You recover better with 4. 10s. :-laf

 

[Wolfy]

New math?

The 4. 10 gears ALWAYS will handle a load better in ALL gears than will a 3. 73. I had heard some say I'll just downshift one gear and still do just as good as a 4. 10. No way. Launches are better, shifting is better, more HP is applied to the ground better and more efficiently. Your rig will buck a head wind better and have less effect on your rig.

I'd like to hear more explanation of this opinion.



"ALWAYS" and "ALL" only apply when both rear axles are behind the same gear, seems to me.



Forgetting about the "launch" (you can't "downshift one gear" from first. ), and assuming same-size tires, we're left with these facts:



The 4. 10 represents about a 10% "downshift" from the 3. 73, from the engine's point of view.



Downshifting one gear with the 3. 73, say from 6>5, or 5>4 , speaking of the 68RFE, represents a 20%-30% downshift.



RPM's and HP go up proportionally.



How is this not at least the power "equal" of the 4. 10-in-one-higher-gear, for a given load condition?



I. e. , to move a given load at a given speed on a given grade (and/or against a given headwind), X HP is required.



Downshifting the 3. 73 one gear from the gear the 4. 10 is in, will give you MORE of that HP (higher RPM, roughly same torque).



Please explain how this is not so.



Whether or not the new RPM is a better(more efficient) or worse match for the conditions-of-the-moment, ... depends on the specific conditions.



There is only one OVERALL gear ratio (trans gear + R. A. ) that will best match a specific speed/load condition. That overall ratio may/may not be the one resulting from the gear/R. A. combination of the moment. There is no gaurantee that the 4. 10 combination will be the closer match. Sometimes yes, sometimes no.



Bottom line, IMO - from a power standpoint ... you can match-or-better all 4. 10 gears EXCEPT the lowest one (1st) by shifting the 3. 73 down. From a fuel efficiency standpoint ... You can match-or-better all 3. 73 gears EXCEPT the highest(6th) by shifting the 4. 10 up.



If you absolutely need a lower gear to get your rig started, the 4. 10 will give it to you.



If you want or need the absolute best mpg potential, the 3. 73 will give it to you.



Choices.



My choice was the 3. 73.



The cummins in first gear ahead of the 3. 73 will get any load I intend to pull moving. After first gear, the choices are up to me, and my gear-limiter switch.

My heaviest load will be a slide-in camper and a 6-8000# boat on a boat ramp. Definitely not a race situation. If the ramp is too steep, a front hitch-receiver will get me an even lower gear to pull-out with (reverse!).



If I was looking to drag race (Not! My chest-beating days are behind me. ), or trying to move one mountain over another from a standing start, I might have gone with the 4. 10.



Your mileage may vary.

 

[CUMMINZ]

:-laf I stand behind everything I said. :-laf

 

[superdave]

I had a 04. 5 with 373 and 5. 9 stock. Pulled 14650# empty weight fifth wheel in overdrive. Never had a problem. Just lost the truck in a head on and am ordering a new one. The 04. 5 ran 70 MPH and 2000 RPM ONly had to use tow/haul when going up a long steep grade. The new one (if I can get what I want) will have the 3. 73 because I drive empty almost all the time.

 

[CUMMINZ]

After driving this 6. 7L with 68rfe with 4. 10s, GM with the allison has ABSOLUTELY nothing over a DC. Driving 70mph @ less that 2000rpms. . :-laf:-laf You can't get no better.

 

[Wolfy]

:-laf I stand behind everything I said. :-laf

Hmmm.



Yes,... well...



Very manly.



But hardly an "explanation".



Part of what you said is this: (with the 4. 10)" Launches are better, shifting is better, more HP is applied to the ground better and more efficiently. "



Launches?

Yes, if that's important to you. Best mpg potential is sacrificed.



Better shifting?

How/why so?



More HP?

Not(!) more than a down-shifted 3. 73. (Higher RPM + equal torque = more HP. )

Physics.

(Downshifting is a bigger gear-ratio change than that between the 4. 10 and the 3. 73,... thus you get higher RPM, higher HP with the one-gear-lower 3. 73 than with the 4. 10, at the same road speed. )



Applied to the ground better ?

Same weight on same tires with same slippage(none) means equal "application" of power (if original HP same. ).



More efficiently?

Maybe/maybe not. As I "explained" before, depends on specific match-up of engine speed/road-speed/load conditions. 3. 73 + gear "X" will sometimes be more efficient. Same for 4. 10.



Am I off track? Save me from myself.



Specific corrections welcome.



Stand/sit anywhere you're comfortable

 

[tgrfan2]

I had a 04. 5 with 373 and 5. 9 stock. Pulled 14650# empty weight fifth wheel in overdrive. Never had a problem. Just lost the truck in a head on and am ordering a new one. The 04. 5 ran 70 MPH and 2000 RPM ONly had to use tow/haul when going up a long steep grade. The new one (if I can get what I want) will have the 3. 73 because I drive empty almost all the time.

I talked my friend into gettig a 3. 73 in his 2003 HO 48re. Now he is waiting on his 07. 5 68rfe 3. 73 to come. I guess we will know when he climbs Saluda mtn with a GCW of 22K if he did the right thing again. I just don't see the advantage of 4. 10s unless you go to bigger tires, pull way over rated wgt, tow at 60mph, or want to drag race. Few tow all the time and the 68rfe certainly looks like it covers the power/ torque range well.

I haven't seen a load or a mountain yet where I wish I had 4. 10s back! If I wanted to really pull, I would go with a 4x4 as I did with my 78 W150 440. I towed a GCW of 32500# many miles with it in low range running a 3. 23 gear and oversized tires.

 

[TowPro]

Thanks, jcarey, for the tip on the Excel Chart by Klenger Dodge.

Ted

Klenger is a member here, not really a Dodge dealership :-laf

Great member, keeps all kinds of info on his website for us.

 

[Wolfy]

Boy I wish I knew that before I ordered mine with the 3. 73's. 4:10's sound like the way to go... [/Q



me too. but mine still runs at 1700 at 70 with the 3. 73 4. 10 just 150 more rpms. will that little of a rpms diff make that big of a diff . if so i might consider changing out.

150 more RPM means some more horsepower. This means some more fuel.



YOUR rig at 70mph might need the higher HP figure. It might not.



What is your load weight/hill-grade/head-wind resistance, compared with driver "X"?



If he is appreciably heavier/climbing steeper/has more headwind than you, and the 4. 10 is perfect for his situation,... then that same 4. 10 in your rig, under YOUR conditions, would be wasting fuel. It would be the equivalent, for you, of driving around in a lower gear, running higher revs and generating more HP than is needed for the task of the moment.



If/when you find yourself in his circumstances, shifting down a gear will get your rpm's and HP up HIGHER than his, and you will have easier going than he will,... at the same speed, ... but will of course pay for that ease in the additional fuel burned to create the greater HP. (you will make up for this fuel "waste" by "saving" more with your higher gear during the easy portions of the run.



That "little of (additional) rpm's" will/will not be desirable, depending on the conditions.



Bottom line,... the 4. 10 guy, with the same transmission(and same tires), in the same gear,... will always be running in a lower OVERALL gear (trans. plus rear axle) than the 3. 73 guy.



Sometimes that is great,... sometimes it's not.



In almost every situation other than starting heavy from a dead stop,... you can get a lower-overall gear than the 4. 10 by shifting down the 3. 73 one-gear.



On the other hand, running light/or heavy-downhill, downwind,etc. ,... i. e. any time your truck is not forced to work hard,... you will have a better mpg potential in the highest gear with the 3. 73.



One size does NOT fit all (conditions).



Slowing down a bit will make more difference that anything discussed here.



Wind resistance goes up with the square of the speed,... and so do internal losses in the engine. (Each air molecule is hitting your truck with twice the force, since each molecule is hitting at twice the speed,... and because you are covering twice the distance in the same time-frame, you are hitting TWICE AS MANY of the DOUBLE-FORCE molecules!) 4 times the air resistance at 2 times the speed.



The additional HP to overcome these (and other) increased resistances comes from your fuel tank/budget.



If hurrying-up doesn't make you more money,... this is worth remembering.