Changing from 3.73 to 4.10 gears

[oakmandan]

Hello all,
After towing our new Reflection 320MKS from Eastern Iowa to Estes Park Colorado and back, I need more power for the hills. I have a 2015 F-250 with the 6.2 Liter engine. I have 3.73 years. Can they be swapped out for 4.10 gears, and will it help ?
Thanks

[4x4ord]

garyp4951 wrote:
Yes your torque will be the same, but a higher number gearing will always give more torque.
I was at a 4x4 truck pull where they see who can pull the other one backwards, and a old 1980 GMC 2500 with 4:56 gears, and small tires was pulling new Fords, Rams, backwards while they were smoking their tires.lol

Like I said I can downshift, which provides a higher number gear ratio resulting in the engine speeding up. This yields the same torque on the rear axle because the Cummins ISX 15 liter engine has a flat power curve over a three gear range of the transmission.

[garyp4951]

Yes your torque will be the same, but a higher number gearing will always give more torque.
I was at a 4x4 truck pull where they see who can pull the other one backwards, and a old 1980 GMC 2500 with 4:56 gears, and small tires was pulling new Fords, Rams, backwards while they were smoking their tires.lol

[4x4ord]

We have 18 speeds in our big trucks and with 18 gears to select from there is always three gear choices available for any one speed. If I'm climbing a hill in 12th gear at a steady 1500 rpm I can shift up to 13th or drop to 11th and neither will make any difference so I'll stay in 12th. If the hill is getting steeper right away I might drop to 11 th or if the truck is accelerating maybe I'll grab 13th. But the torque to the rear wheels is identical regardless of which of those three gears I select.

[goducks10]

I have 4.10's in my Ram 6.4 and can't think of anytime I would want 3.73's when towing.

[4x4ord]

4x4ord wrote:

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

Except that he would no longer be alongside me, or going as fast as me. By the time he is ready to upshift, I will likely be ready for the next shift as well.

The only way your argument works is if both trucks run flatout unimpeded by slower traffic.

Once the trucks slow for any reason, the lower rear geared truck will leave the other one in the dust.
This is an apples to apples comparison. Same trucks, same trannys, same size tires. Just different rear axle ratios.

Ok, we've got identical trucks only difference is mine has 4.10 gears and you have 3.55. I'm right behind you and all of a sudden traffic slows us down by 10 mph. The traffic in front of us turns off the road and we both floor it. Yours drops down to third mine stays in forth and I can't keep up to you even though I have the lower speed axle.

First off, I will be the one with the 4.10s... And 10 MPH slowing isn't much at all. Either truck would do an acceptable job with such a mild slowing. The ones I am talking about, as I originally posted is when I am zipping along at the speed limit of say 65 MPH, and come up on two semis drag racing up the hill at 10-15 MPH..
You with your 3.55s will be left it the dust by me with my 4.10s. In fact you may not ever make it back to 65 before topping the hill.
In many cases you will not even be visible in my mirrors.

Your narrow example of how you can win, just isn't much of an issue at all.

Slowing as I describe it (which seems to happen a LOT) is very frustrating when it happens and you are struggling to get back up to an acceptable speed.
This is WHY lower rear axle trucks are most always rated to tow more. The manufacturers have standards that they use to make sure that their customers have a good towing experience.

It's not that complicated. The advantage goes back and forth from one truck to the other as they accelerate up the hill. If we slow down to 15 mph and floor it the 4.10 equipped truck will be in second gear and will have to let the 3.55 geared truck, which will have dropped to first gear, pass. The advantage moves back and forth depending on speed. The Chevy, with its higher geared rear end and higher first gear in the Allison has won just about every race up the mountain.

It's even easier for those who don't fully understand torque power and gear ratios .... just get the gear ratio that is rated to pull your trailer.

[4x4ord]

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

Except that he would no longer be alongside me, or going as fast as me. By the time he is ready to upshift, I will likely be ready for the next shift as well.

The only way your argument works is if both trucks run flatout unimpeded by slower traffic.

Once the trucks slow for any reason, the lower rear geared truck will leave the other one in the dust.
This is an apples to apples comparison. Same trucks, same trannys, same size tires. Just different rear axle ratios.

Ok, we've got identical trucks only difference is mine has 4.10 gears and you have 3.55. I'm right behind you and all of a sudden traffic slows us down by 10 mph. The traffic in front of us turns off the road and we both floor it. Yours drops down to third mine stays in forth and I can't keep up to you even though I have the lower speed axle.

First off, I will be the one with the 4.10s... And 10 MPH slowing isn't much at all. Either truck would do an acceptable job with such a mild slowing. The ones I am talking about, as I originally posted is when I am zipping along at the speed limit of say 65 MPH, and come up on two semis drag racing up the hill at 10-15 MPH..
You with your 3.55s will be left it the dust by me with my 4.10s. In fact you may not ever make it back to 65 before topping the hill.
In many cases you will not even be visible in my mirrors.

Your narrow example of how you can win, just isn't much of an issue at all.

Slowing as I describe it (which seems to happen a LOT) is very frustrating when it happens and you are struggling to get back up to an acceptable speed.
This is WHY lower rear axle trucks are most always rated to tow more. The manufacturers have standards that they use to make sure that their customers have a good towing experience.

It's not that complicated. The advantage goes back and forth from one truck to the other as they accelerate up the hill. If we slow down to 15 mph and floor it the 4.10 equipped truck will be in second gear and will have to let the 3.55 geared truck, which will have dropped to first gear, pass. The advantage moves back and forth depending on speed. The Chevy, with its higher geared rear end and higher first gear in the Allison has won just about every race up the mountain.

[Huntindog]

4x4ord wrote:

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

Except that he would no longer be alongside me, or going as fast as me. By the time he is ready to upshift, I will likely be ready for the next shift as well.

The only way your argument works is if both trucks run flatout unimpeded by slower traffic.

Once the trucks slow for any reason, the lower rear geared truck will leave the other one in the dust.
This is an apples to apples comparison. Same trucks, same trannys, same size tires. Just different rear axle ratios.

Ok, we've got identical trucks only difference is mine has 4.10 gears and you have 3.55. I'm right behind you and all of a sudden traffic slows us down by 10 mph. The traffic in front of us turns off the road and we both floor it. Yours drops down to third mine stays in forth and I can't keep up to you even though I have the lower speed axle.

First off, I will be the one with the 4.10s... And 10 MPH slowing isn't much at all. Either truck would do an acceptable job with such a mild slowing. The ones I am talking about, as I originally posted is when I am zipping along at the speed limit of say 65 MPH, and come up on two semis drag racing up the hill at 10-15 MPH..
You with your 3.55s will be left it the dust by me with my 4.10s. In fact you may not ever make it back to 65 before topping the hill.
In many cases you will not even be visible in my mirrors.

Your narrow example of how you can win, just isn't much of an issue at all.

Slowing as I describe it (which seems to happen a LOT) is very frustrating when it happens and you are struggling to get back up to an acceptable speed.
This is WHY lower rear axle trucks are most always rated to tow more. The manufacturers have standards that they use to make sure that their customers have a good towing experience.

[4x4ord]

Huntindog wrote:

4x4ord wrote:

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

Except that he would no longer be alongside me, or going as fast as me. By the time he is ready to upshift, I will likely be ready for the next shift as well.

The only way your argument works is if both trucks run flatout unimpeded by slower traffic.

Once the trucks slow for any reason, the lower rear geared truck will leave the other one in the dust.
This is an apples to apples comparison. Same trucks, same trannys, same size tires. Just different rear axle ratios.

Ok, we've got identical trucks only difference is mine has 4.10 gears and you have 3.55. I'm right behind you and all of a sudden traffic slows us down by 10 mph. The traffic in front of us turns off the road and we both floor it. Yours drops down to third mine stays in forth and I can't keep up to you even though I have the lower speed axle.

[Huntindog]

4x4ord wrote:

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

Except that he would no longer be alongside me, or going as fast as me. By the time he is ready to upshift, I will likely be ready for the next shift as well.

The only way your argument works is if both trucks run flatout unimpeded by slower traffic.

Once the trucks slow for any reason, the lower rear geared truck will leave the other one in the dust.
This is an apples to apples comparison. Same trucks, same trannys, same size tires. Just different rear axle ratios.

[4x4ord]

Huntindog wrote:

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

You are a little bit off track. It's true that with a lower gear ratio a race car will pull harder in every gear than the same car with a high rear end however, this does not mean that it, or a pickup truck for that matter, with a lower speed rear gear will pull harder at every speed. So if you are towing with two similar trucks both in the say 3rd gear at 45 mph and one has a lower speed rear end, the low speed rear end one will out pull the other for a while until it shifts into 4th at say 50 mph. Now the higher speed rear end truck has the advantage.

[Huntindog]

mkirsch wrote:
What's saying you MUST stay in that gear?

As long as you aren't in 1st, you can always drop down another gear to accelerate. If you're running out of power in 1st, you probably shouldn't be where you are, OR you've got serious mechanical problems.

In the case of the OP, where he's locking out 6th AND 5th for a majority of the trip, I agree, a gear change is a good idea, and I agree, 4.30 or nothing.

Never said you had to stay in any gear.
The point was that once you slowed down on a steep grade that a lower rear end ratio will allow you to regain speed easier and quicker in all gears.

If you do not believe this... Then there are a lot of drag racers that have been doing it wrong.

[4x4ord]

time2roll wrote:
Yes reminds me of the good old days in my Mustang cruising down the road at 70 mph and 3000 rpm and that was considered normal. After the motor build I saw 7200 rpm a few times in top gear (direct). :B

Wow ... That's 168 mph!!
Now a days that would get you a life sentence if you were pulled over. 🙂

[time2roll]

Yes reminds me of the good old days in my Mustang cruising down the road at 70 mph and 3000 rpm and that was considered normal. After the motor build I saw 7200 rpm a few times in top gear (direct). :B

[4x4ord]

The proper gearing for a gasoline powered tow vehicle is more difficult. To take full advantage of the trucks power band you might want a 5.36 gear ratio behind a 6.2 engine. The trade off is that when cruising empty down the highway in overdrive at 75 mph the engine will be running at close to 2700 rpm and using more fuel than it would if you had a 3.55 ratio. Usually if someone is buying a gasoline powered truck they have in mind that they won't be pulling most of the time.

[4x4ord]

RCMAN46 wrote:
"If the same truck is expected to pull 35000 lbs down that same highway it can be determined that 440 HP can only pull the hill at about 52 mph. It would be desirable for the transmission to again be in 4th gear while the engine is running near 2800 rpm.

This truck will have a little smaller diameter tires and should have a 4.30 rear gear ratio."

Ok but lets assume I have enough horsepower go 60 mph or the hill is a little less grade. Then a 3.73 gear would be best at 2800 rpm and 4th gear.

Yes the 3.73 might be better for that particular hill, it is a matter of selecting the gear ratio that targets the typical use of the truck. If it is rare that you are pulling grades over 4% and often that you run empty up and down the highway you might want a 3.55 axle ratio to tow your 24000 lb rv. The odd time you hit a 6% grade you just let the transmission drop to third gear.