What gears do I need?

[missouri_dave]

Looking at a Ram 2500 to pull a 7K travel trailer. It will be a gasser with the 6.4 hemi. Should I get the 4.10 rear end or will the 3.73 do what I need?

[garyp4951]

I always liked math the best in school, and learned a lot from my Lego set with gears 🙂

[Dave_H_M]

:S I thought about adding something that i thought would be productive, However this thing has gone too far South to ever recover. :B

[BenK]

Parker,

Like your comments, but see some response headers that don't show content
...Don't see comments from those on my blocked list...unless quoted like your quote below...

It is a constant because many do not under this technology, nor have the ability to understand the science & do the simple math well enough to make the correlation from that paper to the real world...free associative skills not high

Plus, get many, many PM's asking to comment...on this and many other topics. Normally only back to them via PM...unless there are more who are lurkers and don't post

Those video's and technical links mostly help...but...many won't go there and learn...or continue to not understand....


PS...this very topic has confused some of my past software engineers...nothing wrong...just the way of it...

parker.rowe wrote:

RCMAN46 wrote:
The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.

Not sure why this keeps getting repeated.

We know gear ratios don't change what the engine puts out.

They multiply (or reduce in the case of overdrive gears) when get's sent to the tires to drive the truck forward.

If they didn't matter, all vehicles would have 1 speed transmissions and 1:1 rear end ratios.

[Grit_dog]

2Rad4U wrote:
4 pages on a pot that was answered in the first two replies. Then the pissing match started...

LOL

That's how the geezernet.net crew rolls!
I'm just trying to take lessons from here on how not to act once I become a member of AARP and forget to take my geritol every other day!

[RCMAN46]

parker.rowe wrote:

RCMAN46 wrote:
The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.

Not sure why this keeps getting repeated.

We know gear ratios don't change what the engine puts out.

They multiply (or reduce in the case of overdrive gears) when get's sent to the tires to drive the truck forward.

If they didn't matter, all vehicles would have 1 speed transmissions and 1:1 rear end ratios.

Statements such as this is why what I stated keeps getting repeated.

"Now back to the above HP formula, there is now a change. The torque remains the same, but RPMs is now larger and multiplies torque. The constant stays the same (divisor is 5252). Nothing else changes, except for the increased (fractional) RPM...therefore, there is more HP.."

[parker_rowe]

2Rad4U wrote:
4 pages on a pot that was answered in the first two replies. Then the pissing match started...

LOL

Well, since the first 2 reply's were exactly the opposite of each other...I wouldn't call it answered that early. But yea, this happens in every gear ratio, half ton, and gas vs diesel thread.

[2Rad4U]

4 pages on a pot that was answered in the first two replies. Then the pissing match started...

LOL

[parker_rowe]

RCMAN46 wrote:
The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.

Not sure why this keeps getting repeated.

We know gear ratios don't change what the engine puts out.

They multiply (or reduce in the case of overdrive gears) when get's sent to the tires to drive the truck forward.

If they didn't matter, all vehicles would have 1 speed transmissions and 1:1 rear end ratios.

[BenK]

Disagree...


First, the formula for determining HP is:

HP = torque x RPM / 5252

A higher numeric gear ratio will have more rev's from the input shaft (pinion gear) for each output shaft turn (ring gear)

The input shaft/pinion's torque is assumed to be the same in all cases for this discussion...in order to NOT get confused like the quote below where they think only increasing the ICE's torque/HP is it...

Since there are more rev's from the input shaft for each output shaft turn, the numbers of input shaft turns will impart more torque onto that output shaft's single turn

Fact.

Now back to the above HP formula, there is now a change. The torque remains the same, but RPMs is now larger and multiplies torque. The constant stays the same (divisor is 5252). Nothing else changes, except for the increased (fractional) RPM...therefore, there is more HP...

Wikipedia Gear train (there are tons more sites)


What is torque and How does gear ratio affect Torque?


YouTube, Gear transfer torque



This one shows the tranny gears and hope it gets it across...ask why you can't get it going in highest gear...even though it is the same ICE?
YouTube,Car Gear Ratios (Calculate Wheel RPMs, Torque at Wheels, and Force at Wheels)

RCMAN46 wrote:
The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.

[parker_rowe]

ib516 wrote:

Beentherefixedthat wrote:

Further the 4:10 will make what is not great gas mileage much worse.

This is NOT the case.

Here is a quote from a GM powertrain engineer:

"How much of a difference does the choice of axle make? A 2013 Sierra 2500HD with a 6.0L V-8 and four-wheel drive can tow a maximum of 9,900 pounds with a 3.73:1 ratio or 14,400 pounds with a 4.10:1 ratio. Martuch estimates the fuel economy difference at highway speeds would be around 0.2-0.3 mpg between those two ratios, though reduced engine noise is also a benefit of maintaining lower engine speeds with the more-efficient ratio.
LINK

"According to Roger Clark, senior manager of GM's Energy Integration and Fuel Economy Learning Vehicles Program, which handles fuel-economy development of all GM trucks and SUVs, fuel economy may not change much by going to an optional axle ratio. "The typical combined-fuel-economy impact, based on lab test conditions, is a difference of about 0.4 mpg to 0.6 mpg between the standard gear ratio (3.42 or 3.55) and the lowest (4.10) offered. That change is linear, too. Choosing 3.73 or 3.92 gear ratios would have even less of an effect on fuel economy." Clark says that in the real world, choosing a lower gear ratio may not even show up in fuel economy associated with city driving. It's the steady-state, long-distance freeway romps where lower axle ratios have the most effect."

It's about 0.5 mpg or so between a 3.42/3.55 and a 3.92/4.10. Not much.

Yep. Obviously my truck is completely different than a new Ram. But I picked up .5-1mpg towing the camper, and lost about the same unloaded.

Going from 3.73's to 4.56's. The difference in towing was huge.

Any new truck I buy will be used for truck stuff, no commuting. So I would always opt for the numerically higher gear ratio if offered. People say to tack on the 10K diesel option just to give you the buffer in capability.
Why do they freak out about doing the same with the $500 option gear ratio to increase tow rating?

[larry_barnhart]

Our 1st rv was a TT. We had a chev van that was very plush with tv etc so that was the tow vehicle 3.42 rear that was not good so changed to 4.10. The tow was much nicer and didn't have to have the pedal to the floor. Maybe the new trucks are different but I agree with ib516.

chevman

[ib516]

Beentherefixedthat wrote:

Further the 4:10 will make what is not great gas mileage much worse.

This is NOT the case.

Here is a quote from a GM powertrain engineer:

"How much of a difference does the choice of axle make? A 2013 Sierra 2500HD with a 6.0L V-8 and four-wheel drive can tow a maximum of 9,900 pounds with a 3.73:1 ratio or 14,400 pounds with a 4.10:1 ratio. Martuch estimates the fuel economy difference at highway speeds would be around 0.2-0.3 mpg between those two ratios, though reduced engine noise is also a benefit of maintaining lower engine speeds with the more-efficient ratio.
LINK

"According to Roger Clark, senior manager of GM's Energy Integration and Fuel Economy Learning Vehicles Program, which handles fuel-economy development of all GM trucks and SUVs, fuel economy may not change much by going to an optional axle ratio. "The typical combined-fuel-economy impact, based on lab test conditions, is a difference of about 0.4 mpg to 0.6 mpg between the standard gear ratio (3.42 or 3.55) and the lowest (4.10) offered. That change is linear, too. Choosing 3.73 or 3.92 gear ratios would have even less of an effect on fuel economy." Clark says that in the real world, choosing a lower gear ratio may not even show up in fuel economy associated with city driving. It's the steady-state, long-distance freeway romps where lower axle ratios have the most effect."

It's about 0.5 mpg or so between a 3.42/3.55 and a 3.92/4.10. Not much.

[ib516]

RCMAN46 wrote:
The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.

You are correct, but the 4.10s do offer more torque at the wheels than the 3.73s do. That will help get heavy loads moving. There is a reason the manufacturer increases the tow rating and GCWR by 3000# when you opt for the 4.10s.

[RCMAN46]

The 4.10 gearing will not give you more horsepower.

Gearing will not change the horsepower of a vehicle period.

Only modifications to the engine can increase horsepower.