3:73 or 4:10

[HBarlow]

For those actually considering the purchase of a new truck and wanting information on which to base your differential gearing choice I ask you this - are you going to believe Dodge engineers who have a large budget for testing our trucks and have published their opinion in writing? Or are you going to believe a self appointed "Internet expert" defending his own choice?

The choice was simple and easy for me. I accepted the information published by Dodge engineers and ordered my '06 and '08 with 4. 10 gears.

I ordered my '01 HO six speed with 3. 55 gears. That gear choice worked great for pulling a relatively light (8,000 lb. ) Airstream travel trailer. Later when I purchased a 14,500 lb. Fifth wheel the gears proved to be a poor choice. The truck would pull it, of course, but launches were not pleasing.

 

[JJPage]

For those actually considering the purchase of a new truck and wanting information on which to base your differential gearing choice I ask you this - are you going to believe Dodge engineers who have a large budget for testing our trucks and have published their opinion in writing? Or are you going to believe a self appointed "Internet expert" defending his own choice?



The choice was simple and easy for me. I accepted the information published by Dodge engineers and ordered my '06 and '08 with 4. 10 gears.



I ordered my '01 HO six speed with 3. 55 gears. That gear choice worked great for pulling a relatively light (8,000 lb. ) Airstream travel trailer. Later when I purchased a 14,500 lb. Fifth wheel the gears proved to be a poor choice. The truck would pull it, of course, but launches were not pleasing.

This ^ is a choice a prospective buyer has to make, there are more options with the new trucks, my whole point all along.



The Dodge Engineers did such a bang up job with the 48re/4:10 pairing, why would you question their judgement? Real world results are not to be considered?



This is an open forum. . right? I can express my opinion and beliefs to the best of my knowledge? That is what I did, I stated all along this is my opinion. As far as being "tagged", "self appointed internet expert"... ohno, that title belongs to 1 individual on this forum. (you have lowered me to your level of name calling... shame on me)



I would never express an opinion/thought or belief, that would steer anyone in the wrong direction, any individual that knows me personally, I am certain, will confirm that.



An 01, w/3:55 differentials would most likely(most likely) been my choice at that time too. There is quite a difference between 8k and 14k behind one of our small trucks, in 01, I would not have even considered pulling 14k with that truck. I believe 14k is really pushing it now, Again, my opinion, not fact.



Have a Good Day ! Jess

 

[NIsaacs]

Yes it does, gearing aside it's too bad Dodge won't put in a clutch/trans that will hold 800 ft/lbs and have 2 OD's.

I agree, however a better option would be direct drive and about a 2. 75 rear. Overdrives have always been the weak point in manuals. I wonder if that is not an issue with auto's (overdrive)?



I also wonder what the tq spec's are with the updated AAM axle? The old Dana 80 was rated 10,000 lb tq intermittent and 2500 lb tq continuous. Using Rusty's graph at 18,610 1st gear launch, may be one reason for the tq. management. Sooo... ... 3. 73's would be less stress



Nick

 

[AH64ID]

Only problem with 2. 75's would be the very low gearing required in the trans in the low gears, it makes for a larger case and more heat as well.

 

[AEdelheit]

Only problem with 2. 75's would be the very low gearing required in the trans in the low gears, it makes for a larger case and more heat as well.

And a tremendous amount of stress on the drive line and rind/pinion

 

[RonD]

The new HO engine with the Max Tow Package has 4:10 gears as standard, it's the only way you can buy it, the 4:10 ratio is there for a reason, I trust the Design Team completely.

 

[NIsaacs]

And a tremendous amount of stress on the drive line and rind/pinion

My guess is, with the push for bigger power and GVW/GCW of the big three, a bigger axle might be in the works. The drivetrain has come a long way in the last 20 years.



Nick

 

[NIsaacs]

Only problem with 2. 75's would be the very low gearing required in the trans in the low gears, it makes for a larger case and more heat as well.

Most manual trannys were/are offered in both direct and overdrive models in medium and heavy duty trucks, including the NV-5600 and the ZF. The only difference is the main drive gear/matching driven countershaft gear in a given model, same case. Not sure where more heat would come from?



Nick

 

[Cummins12V98]

At 60 mph 3:42 6 sp auto in 5th gear what are the rpm's?

Thanks

 

[AEdelheit]

My guess is, with the push for bigger power and GVW/GCW of the big three, a bigger axle might be in the works. The drivetrain has come a long way in the last 20 years.



Nick

Regardless of axle size you are loosing mechanical advantage over the wheels, your U Joints, transfer case, transmission and what not would have to work much harder then a numerically higher gear ratio. There is no getting around that fact.

 

[Barbieri]

He is my little problem that most people aren't aware of. I have an Airstream 31ft classic. I use Goodyear Marathon tires rated for NOT OVER 65mph. So I generally do about 60 and hold it there. I suspect that most people are not aware of this tires or any other tires speed range. I did 70 and blew a tire. After reading the sidewall I realized the limitations of the tire. They are not regular truck tires. They flex more than those type. But thanks for the info.

 

[Barbieri]

I wouldn't trust them How come there are so many auto/truck recalls?

 

[Barbieri]

If your doing 70 mph with an Airstream chances are your exceeding the speed limitations of the Goodyear Marathon tires. Max is 65mph.

 

[AH64ID]

Most manual trannys were/are offered in both direct and overdrive models in medium and heavy duty trucks, including the NV-5600 and the ZF. The only difference is the main drive gear/matching driven countershaft gear in a given model, same case. Not sure where more heat would come from?



Nick

Medium and HD trucks run taller tires for one, and two they aren't designed to be meet light truck speed requirements.



Gear reduction makes heat, if most of your gear reduction is being done in one assembly them most of your heat will be there. With the gear reduction split between trans and 4. 10's you get less heat in each assembly.

 

[Barbieri]

Thanks. I am not looking at a heavy duty truck. Ram 2500 is more my speed. Still I appreciate your info. Have a nice day.

 

[mwilson]

Medium and HD trucks run taller tires for one, and two they aren't designed to be meet light truck speed requirements.



Gear reduction makes heat, if most of your gear reduction is being done in one assembly them most of your heat will be there. With the gear reduction split between trans and 4. 10's you get less heat in each assembly.

Back in my Class 8 driving days (with trucks that have a full complement of gauges) you saw the most heat in all the components created when pulling long steady grades at full rated capacity (or a little bit more. . :-laf) with the engine in it's torque curve. Gear ratio didn't matter as much in that circumstance with 10 to 18 speed transmissions.



Engines with great torque characteristics (such a Mack E6 350) would heat things up in a hurry because the little dog just didn't give up in a hill and you could sack it down to 1400 rpm and it just kept on pulling.



Torque makes heat. Lots of torque, lots of heat.



I could overheat a 10 speed Fuller every time on Jabob's Ladder Westbound on the Mass Pike (I-90).



Transmissions would run at 150 degrees or so until you brought the torque up, then would climb steadily upward for the duration of the pull. Back then we did not have coolers or internal pumps on the Fullers and the interesting thing was that the gearbox would not cool down after coasting down the other side and continuing on.



I would plan to stop for a half hour or so after a hard pull on a hot day because the transmission would not cool down otherwise until you completely shut it down.



The forward rear axle always ran 50 degrees hotter than the rear unit because of the extra gears in the power divider. So more gears spinning in a case generate more heat as well.



These Cummins powered torque animals that we all have are capable of generating loads of drive component heat as well so a numerically lower ratio keeps the engine from pulling a load at it's peak output quite so frequently and when it has to pull hard it will be for a shorter duration of time which again will keep the heat down.



Mike.

 

[NIsaacs]

Medium and HD trucks run taller tires for one, and two they aren't designed to be meet light truck speed requirements.



Gear reduction makes heat, if most of your gear reduction is being done in one assembly them most of your heat will be there. With the gear reduction split between trans and 4. 10's you get less heat in each assembly.

Yes, I agree with all you said. However, taller tires or gears is kinda the same. Also, the manual transmission in a pickup is mostly running in it's top gear or in the case of a direct transmission, no heat, torque or stress is generated. transmission heat is generated from torque transmitted by the counter shaft, so any reduction or overdrive, heat will be generated. Direct or straight through, equals no heat. I usually look for an excuse to down shift out of 6th to 5th for this reason.



I always figured that the higher the rear axle ratio, the larger the pinion. This means more tooth contact or less heat and more strength. This thought is just an opinion however, I can't prove or disprove it



Nick

 

[AH64ID]

Yes, I agree with all you said. However, taller tires or gears is kinda the same. Also, the manual transmission in a pickup is mostly running in it's top gear or in the case of a direct transmission, no heat, torque or stress is generated. transmission heat is generated from torque transmitted by the counter shaft, so any reduction or overdrive, heat will be generated. Direct or straight through, equals no heat. I usually look for an excuse to down shift out of 6th to 5th for this reason.



I always figured that the higher the rear axle ratio, the larger the pinion. This means more tooth contact or less heat and more strength. This thought is just an opinion however, I can't prove or disprove it



Nick

I haven't looked at one torn apart, or a schematic, but I would think that direct would still involve gears, or you couldn't have other gears, N, or R. So there has to be some gear:gear contact, which will create heat. . just not as much as gear reduction/overdrive.



Personally I like a balance between the trans and the rear end. I still truly think a 4:10's with a 7 speed manual and 2 OD's would be the best.



Yeah as you go lower (numerically higher) your pinion size does decrease, but on a 11. 5" ring gear I am not sure how low you would have to go to sacrifice strength. On the 8" Toyota axles 5. 38's is starting to get too small of a pinion, so I would say 4. 10's are no weaker (at least in this application) than 3. 42's would be.

 

[NIsaacs]

Yes, those dang little Mack's in the log woods could give us owner-op's fits. We all had big power and lotsa gears and all this one company I hauled for had were the Mack's with the triple counter shaft 5spd direct transmission's and the two spd splitter, deep under and direct. They run the 4. 50 or 4. 63 Mack rears and toped out at 65 mph. We were running either the 5. 29 and one overdrive or 6. 14's and two overdrives. The trq. them little motors made was amazing! I had an older one with the 674 pre maxi-torque, quadruplex transmission and turned up it could give a good running 335 Cummins a good run.



Nick

 

[Barbieri]

Thanks for the information. It was just a little more than I was looking for. I just want a simple 2500 Ram. So lets keep it simple. Rule 1: Nothing above Ram 3500. Have a nice day.