3.21 vs 3.92 Gear Ratio...will not be towing much.

[CheechDogg.0n37s]

Just really amazes me how so many people are quick too assume someone is lying about their trucks especially when it comes to MPG on this forum ... lol ... what do I gain by lying about the MPGs my truck is getting ? ha ! lol .. gottah love it !

 

[CheechDogg.0n37s]

Agreed. This was over the course of a 3 hour trip on the freeway. I did not reset, but it doesn't matter one way or the other, since when you run for that long the previous MPG is discarded. It's a rolling average, using only the last few hundred miles/kms.

So that 25 MPG is all freeway, and is accurate. I'm not doing a reset on the middle of the highway and then quickly taking a screen shot. It's also reproducible, I have done it several times and each time it's >= 23 mpg depending on how hard I try or if I'm in a hurry etc. It's also with MDS disabled BTW, I never use it.

And you just said it ...that is all freeway not in town driving added into that equation ... mine is all in-town no highway because here in California I try to avoid the damn freeway as much as I can ... which is why I said earlier that if I tried to get 25 mpg hoping on that freeway for a long trip I will probably hit the 25 mpg even with the 37s and 4.88s which you don't think can happen which is fine lol ... but remember you saying that you are the one trying to get those 25 mpgs lol not me ....

 

[ramffml]

And you just said it ...that is all freeway not in town driving added into that equation ... mine is all in-town no highway because here in California I try to avoid the damn freeway as much as I can ... which is why I said earlier that if I tried to get 25 mpg hoping on that freeway for a long trip I will probably hit the 25 mpg even with the 37s and 4.88s which you don't think can happen which is fine lol ... but remember you saying that you are the one trying to get those 25 mpgs lol not me ....

I never accused you of lying, by the way. You never said you did get it, you just sort of implied you could get it. At least that's how I interpreted it, and that is what I'm responding to.

You don't need to take a screenshot as proof, because I know you won't get it. It's a physics problem, one that you will fail based on my experience where I know I wasn't cheating. You simply will not get better MPG then my truck, driver differences notwithstanding.

You would not get even if you had an identical truck except with the 3.92. Now add in your jacked lift and massive tires, any of those by themselves is good for at least 2 to 3 off the top. Stock 5th gen Rebels on the other forum are getting like 15 to 19 on the freeway on a good day with a stiff tail wind.

 

[ramffml]

Mine sits about 20 on a run like that but weighs over 6k and has 3.92s

What's your available payload, if I may ask?

 

[bobbo7915]

so.....OP did you buy a truck yet?

 

[CheechDogg.0n37s]

I never accused you of lying, by the way. You never said you did get it, you just sort of implied you could get it. At least that's how I interpreted it, and that is what I'm responding to.

You don't need to take a screenshot as proof, because I know you won't get it. It's a physics problem, one that you will fail based on my experience where I know I wasn't cheating. You simply will not get better MPG then my truck, driver differences notwithstanding.

You would not get even if you had an identical truck except with the 3.92. Now add in your jacked lift and massive tires, any of those by themselves is good for at least 2 to 3 off the top. Stock 5th gen Rebels on the other forum are getting like 15 to 19 on the freeway on a good day with a stiff tail wind.

And again I'm getting 15 with 37s and 4.88s lol while stock Rebels are getting the same as me and you just posted that ... so I like my chances of getting 25 on the freeway on a long trip ....

Sent from my SM-T387V using Tapatalk

 

[Farmer Fran]

Just really amazes me how so many people are quick too assume someone is lying about their trucks especially when it comes to MPG on this forum ... lol ... what do I gain by lying about the MPGs my truck is getting ? ha ! lol .. gottah love it !

I how you are not implying me? I was talking to the guy with 25mpg and I was not implying he was lying either. Just that getting a picture of the fuel screen is more descriptive

 

[ramffml]

It's far easier for a 3.92 rebel to match a 3.21 in the city, than it is on the highway. Like almost exponentially easier. To go from 23 to 25 mpg requires a metric **** ton of effort more, than it does to go from 15 to 17.

It's not going to happen, but sweet dreams anyway.

 

[Farmer Fran]

What's your available payload, if I may ask?

It is burried somewhere in these 13 pages

1090 payload and 10990 towing

 

[CheechDogg.0n37s]

I how you are not implying me? I was talking to the guy with 25mpg and I was not implying he was lying either. Just that getting a picture of the fuel screen is more descriptive

No Fran not you ... and yes I knew you were talking about "the guy with 25mpg" lol ... but he sure has implied that about others especially the 3.92 guys like he said a few posts back lol ... again what does one get out of lying about something like this ... he sure as hell doesn't seem to think that my truck with 37s and 4.88s gears is getting high 14s and low 15 MPGs and that is in town driving normally ... when I do floor the pedal in town I am averaging about 11-13 MPGs again only in town ...

My point is that you don't need the 3.21s to get the 15 MPG that others seem to have a problem getting with 3.21s ... I have done it with 3.21s, 3.92s, 3.55s and now with my 4.88s lol ..... the OP wants best possible MPGs out of either one and you can definitely get good MPGs even with the 3.92s which would be more beneficial IMO as you can get the both of both worlds with just a little sacrifice in MPGs which is minimal and IMO outweights the cons of having 3.92s over 3.21s ....

 

[ramffml]

It is burried somewhere in these 13 pages

1090 payload and 10990 towing

Oof. So between your truck and mine, it's a great example of what I've been trying to explain.

My truck has 1750 pounds of payload, but is rated to tow 8550 pounds.
Your truck has 1090 pounds of payload, but is rated to tow 10990 pounds.

If we attach an 8000 pound trailer, at 13% tongue weight, we use 1050 pounds of payload. I weigh 200 pounds, wife at 200 pounds, no cargo, but 50 pounds for WDH.

So both trucks, with that trailer and passengers inside, are using 1050 + 450 = 1500 pounds of payload. Again, no cargo in truck, just driver + passenger + WDH.

Your truck is exceeding its payload by 410 pounds!
My truck still has 250 pounds left for cargo.

So, whose truck can actually pull that trailer? Not yours, even though it's rated to tow more with the 3.92

Not saying this specifically at you, but in general: Please don't ignore the payload factor!!

 

[ramffml]

No Fran not you ... and yes I knew you were talking about "the guy with 25mpg" lol ... but he sure has implied that about others especially the 3.92 guys like he said a few posts back lol ... again what does one get out of lying about something like this ... he sure as hell doesn't seem to think that my truck with 37s and 4.88s gears is getting high 14s and low 15 MPGs and that is in town driving normally ... when I do floor the pedal in town I am averaging about 11-13 MPGs again only in town ...

My point is that you don't need the 3.21s to get the 15 MPG that others seem to have a problem getting with 3.21s ... I have done it with 3.21s, 3.92s, 3.55s and now with my 4.88s lol ..... the OP wants best possible MPGs out of either one and you can definitely get good MPGs even with the 3.92s which would be more beneficial IMO as you can get the both of both worlds with just a little sacrifice in MPGs which is minimal and IMO outweights the cons of having 3.92s over 3.21s ....

There is no MPG difference in the city between 3.21 and 3.92. None. A guy driving a 3.92 can easily beat a guy driving a 3.21 depending on driving style.

Where the difference is, is in the freeway, and only on the freeway where the 3.21 can utilize a super tall gear ratio that the 3.92 does not have.

THAT, combined with your lifted truck (increased air drag) and heavy bubbly tires is why you will never reach 25 mpg. And THAT is why I said your screencaps showing mainly city usage is proving nothing.

 

[CheechDogg.0n37s]

There is no MPG difference in the city between 3.21 and 3.92. None. A guy driving a 3.92 can easily beat a guy driving a 3.21 depending on driving style.

Where the difference is, is in the freeway, and only on the freeway where the 3.21 can utilize a super tall gear ratio that the 3.92 does not have.

THAT, combined with your lifted truck (increased air drag) and heavy bubbly tires is why you will never reach 25 mpg. And THAT is why I said your screencaps showing mainly city usage is proving nothing.

Oh now you really gone and bumped your head if you think there is no difference in MPGs between the 3.21 and 3.92 lol .... you are seriously too much .... thank you for the laugh

 

[swapwap]

Air shocks will really improve ride and aero. I have the bigger gear in a 15. 4x4 but can still get 20mph on the hwy if I baby it

 

[ramffml]

Oh now you really gone and bumped your head if you think there is no difference in MPGs between the 3.21 and 3.92 lol .... you are seriously too much .... thank you for the laugh

I'm not surprised you think there is a difference, you clearly don't understand how it works.

MPG is based on 2 factors (if all else in the trucks, and wind conditions etc are the same); MPH, and RPMs. That's it.

If your RPMs go up, you use more fuel. Since both 3.21 and 3.92 have the ability to upshift to reduce the RPMs while keeping MPH the same, then both have the same advantage.

That is why there is only a difference on the highway when the 3.21 can utilize the tallest gear ratio it has (2.0544), whereas the tallest gear ratio the 3.92 has is 2.5088.

In the city, the same gear ratios are available to both trucks. Same gear ratio means same RPMs at that speed. Same RPMs means same fuel usage.

 

[blahargoue]

Here's a direct comparison. My friend and I identically equipped Gen 5 Laramie trucks, both with Hemi's. He has 3.21 ratio and I have the 3.92. He no longer tows anything, I tow 9000 lbs. His truck get about 1 mpg better than mine on the highway than mine under similar driving conditions. (19 mpg v. 20 mpg under ideal circumstances.)

 

[pacofortacos]

The rear gear ratio just isn't as important for towing as it was in the past.
Because it just isn't the rear ratio, it is the overall gear ratio.

An 8 speed with 3.21's gears will absolutely smoke a 6 speed ram with 4.10's in towing from a dead start.
Below are the trans ratios.
Note
8 speed with 3.21 gears = 15.12 overall gear ratio in first gear.
6 speed with 4.10 gears =13.24 overall gear ratio in first gear.
Guess which is faster and more pulling power from a dead stop.

8 speed -
1) 4.71:1
2) 3.14:1
3) 2.10:1
4) 1.67:1
5) 1.29:1
6) 1.00:1
7) 0.84:1
8) 0.67:1
Reverse) 3.30:1

5 speed 545RFE
Gear Ratios 545RFE:
1st 3.00:1
2nd 1.67:1
2nd Prime 1.50:1
3rd 1.00:1
4th 0.75:1
5th 0.67:1
Reverse 3.00:1

68RFE

• 1st 3.23:1
• 2nd 1.83:1
• 3rd 1.41:1
• 4th 1.00:1
• 5th 0.81:1
• 6th 0.62:1
• Reverse 4.44:1
  
  

 

[Farmer Fran]

Oof. So between your truck and mine, it's a great example of what I've been trying to explain.

My truck has 1750 pounds of payload, but is rated to tow 8550 pounds.
Your truck has 1090 pounds of payload, but is rated to tow 10990 pounds.

If we attach an 8000 pound trailer, at 13% tongue weight, we use 1050 pounds of payload. I weigh 200 pounds, wife at 200 pounds, no cargo, but 50 pounds for WDH.

So both trucks, with that trailer and passengers inside, are using 1050 + 450 = 1500 pounds of payload. Again, no cargo in truck, just driver + passenger + WDH.

Your truck is exceeding its payload by 410 pounds!
My truck still has 250 pounds left for cargo.

So, whose truck can actually pull that trailer? Not yours, even though it's rated to tow more with the 3.92

Not saying this specifically at you, but in general: Please don't ignore the payload factor!!

And guess what - I neither want to nor need to tow that but my truck is 660lbs nicer than yours. Actually more, but I am being nice tonight -

EDIT: THat came off snide and that was not my point...!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Fancy = lees weight

You can find my post about the new Tahoe that will out tow even your 3.21 RAM - yes it it stupid.

EDIT EDIT and that Tahoe has IRS

 

[ramffml]

And guess what - I neither want to nor need to tow that but my truck is 660lbs nicer than yours. Actually more, but I am being nice tonight

Your truck is indeed nicer than mine.

That was not the argument though. I wasn't trying to put down your truck, but simply point out that having a 3.92 does not automatically mean you can tow more than someone with a 3.21, even though the tow rating seems to suggest it.

 

[ramffml]

You can find my post about the new Tahoe that will out tow even your 3.21 RAM - yes it it stupid.

EDIT EDIT and that Tahoe has IRS

https://tfltruck.com/2020/05/2021-c...pg-and-towing-specs-officially-revealed-news/

Doesn't look like it to me. Depends on trim, but I have more payload than most of those listed there, and also more towing capacity (when comparing 4x4 models to my 4x4). Looks like we're both kind of even for the most part.

But yes, it's a half ton platform with the same drivetrain as their 1500 trucks, it should have very similar numbers.