3.31 gears at 40,000 lbs gross.

Grit dog wrote:
I will say 4x4ord, you have had better luck on this fishing trip than the previous one about the bump stops!
Proof that sometimes it’s not the lake, but rather the bait you’re using...

:B

Is is not true that the pinion gear in a 4.10 diff is not as strong as one in a 3.31 diff? Or is it the ring gear? Just saying! I loved the tall gears in my former 2015 SRW RAM with Aisin. I thought I had the best of both worlds. 1750 RPMs that 80 MPH yet towed heavy without issues.

dodge guy wrote:

mkirsch wrote:

dodge guy wrote:
Yes but the engine and trans are working harder in each of the gears with wrong gearing!

No, they are not. They are working the same. Same input engine RPM. Same output wheel RPM. How it gets from A to B does not matter.

What does matter is having 9 and 10 available when NOT TOWING for efficient cruising.

You guys who are still adamant that 3 gears are plenty, are complaining about using "only 8?"

You have to understand physics and how the transmission and rear end gearing work with each other. It’s more than just running the trans one gear lower.

Share the physics for us. I'm an engineer so you can use big words.

At best you may come up with a percent or two difference in efficiency but without a detailed analysis of all the loses, could say if that difference is positive or negative...but running light, it's well established that a lower numerical rear end is more efficient.

If the final gear ratio is 4-1, the engine etc does not care if it is a 1-1 in trans or axel, 4-1 in other, or 2-1 in both, the final is 4-1, engine is turning the same rpm, etc.
Reality, if the combined ratios equal ea other between two rigs one has a 4.19, other a 3.31, transmission gears equal splits, both rigs should have the same performance, gear changes, mph at same time etc.
But having the choice of talker vs lower gears in pumpkins. Gives a person like 4x in flat lands, drives empty at 70-80 mph, talker gears give him better final ratios, lower gears give me better overall performance, as I generally drive 0-60 loaded or unloaded.
Neither setup is best per say, only what is best for the person running that drivetrain.

Marty

mkirsch wrote:

dodge guy wrote:
Yes but the engine and trans are working harder in each of the gears with wrong gearing!

No, they are not. They are working the same. Same input engine RPM. Same output wheel RPM. How it gets from A to B does not matter.

What does matter is having 9 and 10 available when NOT TOWING for efficient cruising.

You guys who are still adamant that 3 gears are plenty, are complaining about using "only 8?"

You have to understand physics and how the transmission and rear end gearing work with each other. It’s more than just running the trans one gear lower.

I will say 4x4ord, you have had better luck on this fishing trip than the previous one about the bump stops!
Proof that sometimes it’s not the lake, but rather the bait you’re using...

^Like button for mkirsch!

dodge guy wrote:
Yes but the engine and trans are working harder in each of the gears with wrong gearing!

No, they are not. They are working the same. Same input engine RPM. Same output wheel RPM. How it gets from A to B does not matter.

What does matter is having 9 and 10 available when NOT TOWING for efficient cruising.

You guys who are still adamant that 3 gears are plenty, are complaining about using "only 8?"

dodge guy wrote:

valhalla360 wrote:

dodge guy wrote:
If it worked the way you said then the manuf would recommend that to tow a certain amount of weight you would lock out Ome of the top gears for that particular weight rating!

Effectively, that's what they are doing. They just do it automatically. If the truck can only hold 8th gear, it won't use 9 and 10.

You are seeing fewer rear end ratios available and they tend to be lower (numerically).

The main reason to consider a higher (numerically) ratio is if the lower ratio doesn't have a tow rating sufficient for your trailer. If it's within the tow rating, the transmission will effectively lock out a gear or two so the overall gear ratio keeps the engine happy.

Yes but the engine and trans are working harder in each of the gears with wrong gearing!

The engine has no clue how the gear ratio was achieved. With the 8/10speed transmissions, that's the big advantage. It can pick the gear that keeps the engine in the best RPM/power output range. As far as the engine is concerned, it's in the perfect gear regardless of what rear end you have.

Assuming the transmission lock the torque converter in the chosen gear, the transmission doesn't really care what gear it runs in. In the old days when only the top gear would lock the torque converter, this would be a difference if you couldn't hold top gear. As long as you don't exceed the tow ratings for the truck, shredding gear teeth shouldn't be a problem. The transmission doesn't really care.

dodge guy wrote:

valhalla360 wrote:

dodge guy wrote:
If it worked the way you said then the manuf would recommend that to tow a certain amount of weight you would lock out Ome of the top gears for that particular weight rating!

Effectively, that's what they are doing. They just do it automatically. If the truck can only hold 8th gear, it won't use 9 and 10.

You are seeing fewer rear end ratios available and they tend to be lower (numerically).

The main reason to consider a higher (numerically) ratio is if the lower ratio doesn't have a tow rating sufficient for your trailer. If it's within the tow rating, the transmission will effectively lock out a gear or two so the overall gear ratio keeps the engine happy.

Yes but the engine and trans are working harder in each of the gears with wrong gearing!

Why is an automatic in the wrong gear ..... I guess it would be in the wrong gear if someone has 4.30 gears to pull a 20,000 lb trailer and the engine has to spin 1900 rpm in 10th because the tranny can’t upshift anymore? That would be wrong gearing.