Ram Pentastar towing

[KrisZ]

Originally Posted By: supton
...11% is close-ish to half a gear, so perhaps it just optimizes the system that much better.


And it's the whole system that matters. I'm not an automotive expert as my major is in electo-mechanics. With electric motors you don't have to worry about RPM for making torque. So when designing a system you can pretty much work off of the tables with HP, TQ numbers and optimal RPM.

Gas engines are totally different. You have to consider bearing loads, lower RPM means more load on the bottom end, pre-ignition, combustion efficiency, temperatures etc. They all change with RPM and for gasoline engines in general, raising the RPM solves a lot of these issues.

 

[WyrTwister]

An expensive option , if still avalable , if to install a 2 speed diff , like the trucks I used to drive .

 

[supton]

Originally Posted By: WyrTwister
An expensive option , if still avalable , if to install a 2 speed diff , like the trucks I used to drive .
I've wondered about that. It's not like it'd have to be a big gear difference. Say one gear down, a 20-30% reduction. That's not too far from what people used to consider towing vs highway gears. But I recall reading that for planetaries, the smaller the gear ratio the higher the losses. Plus it might make the transmission bigger (egads!), or worse, need to be between trans and transfer case.

What might make some sense is to rework low range in the transfer case and allow 2Lo for highway. Maybe not so deep low.

Eh. Truth is, most people who plan to tow, are going to jump to the Hemi or go to a larger truck. This is just splitting hairs.

 

[demarpaint]

Do they offer it with a 3.73 rear? If so that's what I'd get.

 

[Nick1994]

Originally Posted By: demarpaint
Do they offer it with a 3.73 rear? If so that's what I'd get.
10k pound capacity?

 

[WyrTwister]

Also , what % of the time will you be towing ? What % of the time will you be driving it like a car ?

 

[supton]

Originally Posted By: WyrTwister
Also , what % of the time will you be towing ? What % of the time will you be driving it like a car ?


Probably very little towing, mostly car usage. Based on how I wound up using my current truck. But one never knows--I had high hopes of a nice travel trailer when I bought mine. Plus I have hills around here. Lots of rolling hills. Deeper gearing has its use I think.

Just keeping my knowledge up. No plans to replace, when I do I'll likely wind up in a minivan, but I sure do like having a truck. I keep my miles low by driving a car when all I need is four doors.

 

[WyrTwister]

Hills are not an issue , where I live .

 

[demarpaint]

Originally Posted By: Nick1994
Originally Posted By: demarpaint
Do they offer it with a 3.73 rear? If so that's what I'd get.
10k pound capacity?

I don't know about that, but for me it would be better than the other two mentioned. The transmission would do a lot less down shifting in head winds, on hills, mountains, and towing on the highway.

 

[SteveSRT8]

Precisely why my 2014 RAM has a 3.91 rear end. Tows whatever you want to!

 

[supton]

Yeah, 3.92 would be something else! Funny how the least torquey motors seem to get stuck with the tallest gears. CAFE games I bet--makes one wonder if both had 3.92's just how bad the mpg would be, unloaded.

Regardless, if I ever got one, I'd make use of the gear selector. I do that in all my vehicles, look at the terrain, downshift early, or just lock out gears when there's no need for 'em.

 

[SteveSRT8]

Originally Posted By: supton
Yeah, 3.92 would be something else! Funny how the least torquey motors seem to get stuck with the tallest gears. CAFE games I bet--makes one wonder if both had 3.92's just how bad the mpg would be, unloaded.

Regardless, if I ever got one, I'd make use of the gear selector. I do that in all my vehicles, look at the terrain, downshift early, or just lock out gears when there's no need for 'em.


The ZF 8 speed is equipped with two overdrive gears so there is no penalty for the "short" rear gears. Still averages almost 19 mpg even with a heavy footed wife at the wheel. Add to that it is the first autobox I have ever driven that shifts perfectly/smoothly when executed manually with the steering wheel buttons. Plus, if you drop it into "tow/haul" mode it holds the gears to much higher rpms, yet never a rough shift. Great Gearbox IMO...

 

[JTK]

Originally Posted By: supton
Originally Posted By: WyrTwister
Also , what % of the time will you be towing ? What % of the time will you be driving it like a car ?


Probably very little towing, mostly car usage. Based on how I wound up using my current truck. But one never knows--I had high hopes of a nice travel trailer when I bought mine. Plus I have hills around here. Lots of rolling hills. Deeper gearing has its use I think.

Just keeping my knowledge up. No plans to replace, when I do I'll likely wind up in a minivan, but I sure do like having a truck. I keep my miles low by driving a car when all I need is four doors.


Four of my work mates have 2016-17 Ram 5.7's. I believe 3 are big horn additions, one is a click or two above mine. SLT maybe? Talking with them recently after buying mine, these ALL have 3.21 ratios. None of these guys tow anything special though and definitely didn't even consider rear end ratios from the get go. My point is, I think the majority of the Rams you'll find on the lot are 3.21s.

If you do any reading on busy Ram forums, the guys there think nothing of exceeding the 3.21 combo. I don't know that I've read on anyone with the Pentastar and 3.21 towing in excess of the spec.

In regards to the minivan thing, my 2017 Ram 3.6l blows away any minivan I've owned in terms of fuel economy. Our current 2016 Nissan quest does about 19mpg with daily driving. My Ram gets 23 without even trying and that's calculating it by hand.

 

[supton]

Once I threw on snows I found I rarely used 4WD in my Tundra. I think the only times I've used it since was either when driving too fast in the snow or pulling people out of ditches. Both of which may have obvious workarounds... I wonder if a 2WD Ram could gain 3.92's on the cheap. Just one pumpkin to change, reflash the ECU, done. Assuming it was needed. Assuming one bought a used truck and felt like dropping (a grand, maybe?) on it. If it felt like it was needed.

 

[demarpaint]

Originally Posted By: SteveSRT8
Precisely why my 2014 RAM has a 3.91 rear end. Tows whatever you want to!


I'd take that if it was offered too. All that power can be put to much better use with those gears.

 

[supton]

Originally Posted By: demarpaint
Originally Posted By: SteveSRT8
Precisely why my 2014 RAM has a 3.91 rear end. Tows whatever you want to!


I'd take that if it was offered too. All that power can be put to much better use with those gears.


No doubt, but... 4.71*3.92 is an 18.5:1 takeoff gear. The 5.7L Tundra is 3.33*4.3 for a 14.3:1 takeoff (I believe the 5.3L Silverado is 4*3.42 for 13.68?). I haven't looked to see differences in towing, but IIRC both are around 10k. I'm sure it feels better, but I have to wonder if torque management winds up working hard in 1st (and 2nd?), and kinda negates the gain. Not sure if torque management strives to save trans or rear gears--if trans then deeper rear gears restores lost torque, if rear gears then not.

*

To ward off the question (which I'm surprised hasn't come up), I like looking at different vehicles. One never knows when a vehicle might get totaled out, so having some idea as to a replacement plan isn't wasted time, at least not in my opinion. As I contemplate the 5 years I've had my Tundra, at times I do wish it had a backup camera, and more mpg is always a good thing. The Pentastar seems to be pretty straight forward: DI may be proven, as is displacement on demand, as are turbos--at least depending upon who you talk to--but this engine gets around all that. While being a bit cheaper to buy. Only other issue left over is just how high the vehicle is off the ground, for ingress/egress, and for cargo loading, but that's just plain common to all trucks these days.

I also haven't (quite) given up my quest for a travel trailer. It'd be a nice place to store visitors when they stay over. Those get too big too quickly for a minivan, IMO.

 

[SteveSRT8]

Originally Posted By: supton

No doubt, but... 4.71*3.92 is an 18.5:1 takeoff gear. The 5.7L Tundra is 3.33*4.3 for a 14.3:1 takeoff (I believe the 5.3L Silverado is 4*3.42 for 13.68?). I haven't looked to see differences in towing, but IIRC both are around 10k. I'm sure it feels better, but I have to wonder if torque management winds up working hard in 1st (and 2nd?), and kinda negates the gain. Not sure if torque management strives to save trans or rear gears--if trans then deeper rear gears restores lost torque, if rear gears then not.


The torque management is extreme in ours. That 400+ foot pound hemi is ready to go but the computer will not give full throttle until 3rd gear. Very noticeable.

Still impressive to hear a 5k pound truck get rubber from a roll...

 

[IndyIan]

Originally Posted By: SteveSRT8
Originally Posted By: supton

No doubt, but... 4.71*3.92 is an 18.5:1 takeoff gear. The 5.7L Tundra is 3.33*4.3 for a 14.3:1 takeoff (I believe the 5.3L Silverado is 4*3.42 for 13.68?). I haven't looked to see differences in towing, but IIRC both are around 10k. I'm sure it feels better, but I have to wonder if torque management winds up working hard in 1st (and 2nd?), and kinda negates the gain. Not sure if torque management strives to save trans or rear gears--if trans then deeper rear gears restores lost torque, if rear gears then not.


The torque management is extreme in ours. That 400+ foot pound hemi is ready to go but the computer will not give full throttle until 3rd gear. Very noticeable.

Still impressive to hear a 5k pound truck get rubber from a roll...

I wonder if the torque management would change with different rear end ratios? I do understand the advantages of a high ratio rear end, but you would think having so many ratios in the transmission would make the actual rear end ratio irrelevant. I guess tightening the gap between the first 3 or 4 gears even a little with a high ratio rear end still gives noticeable results.