Question about axle Ratios

"Most" is the key word there. Not all. I don't even drive a 1/2 ton but the arguements are relentless and constant...

four22 wrote:
"Most" is the key word there. Not all. I don't even drive a 1/2 ton but the arguements are relentless and constant...

Yep, it can get that way.
But...
The Op listed the truck model, the axle ratios, and the gross weight he was looking at towing. He wanted opinions on towing. He certainly got that and a little more.
To a lot of us here, weights matter.
Towing safety matters and weight has a lot to do with that.
Axle ratios can determine how acceptable the towing experience is.
So, it is all tied together.
And besides, it can be very entertaining and even educational.

SoundGuy wrote:

four22 wrote:
.

... tow too much trailer with most 1/2 ton trucks and you're going to exceed payload capacity. It goes with the territory, whether you agree or not. :R

You do know that statement applies to ALL trucks. You can exceed the payload of any truck. From a 1/4 ton to a 40 ton.

four22 wrote:
.

SoundGuy wrote:
... tow too much trailer with most 1/2 ton trucks and you're going to exceed payload capacity. It goes with the territory, whether you agree or not. :R

Terryallan wrote:
You do know that statement applies to ALL trucks. You can exceed the payload of any truck. From a 1/4 ton to a 40 ton.

You're parsing words here just for the sake of it. :R The OP said in his opening post -

"Looking at two, 2017 RAM 1500 Laramie Trucks. One has a axle ratio of 3.21 and has a lot of options I like. The second one has a ratio of 3.92 but with less options, prices on both are very similar. Looking to purchase a TT with a gross weight of 7500 to 8000 pounds. Am I ok with the 3.21, assuming I will not be doing a lot of mountain driving?"

My response which was specifically addressed to the OP is that a trailer this heavy is too much for either of these trucks as it's not just about axle ratio but also real world payload capacity. For anyone towing, these are the two most important considerations that need to be addressed - ignore them and you're sure to be disappointed. :(

Terryallan wrote:

PUCampin wrote:
Axle ratio is A LOT less important than it used to be with todays wide ratio 6 8 or 10 speed transmissions. Crawl ratio with a modern 6 speed and a 3.21 is better than the old 4spds with a 4.56. The gears are closer spaced making it easier to keep in the power band. Given a choice, the 3.92 is better and will be more enjoyable, but a 3.21 is not a deal killer like it used to be.

Payload is the biggest issues with half tons, especially Ram. A few years ago Ram changed their general design philosophy to aim more squarely at the demographics. The vast majority of 1500 buyers want a nice car with a big trunk to carry awkward items and maybe to tow the jet skies or the bass boat to the lake. Most people looking to tow a RV were looking at 2500. So they softened the ride and added amenities to the 1500 to aim for the biggest audience. The result is if looking at a Ram and planning to tow anything bigger than a speed boat, you should be looking at a 2500. That is what Ram intends, but unfortunately most salesmen don't know or understand this and just want you to sign on the line.

Hmm. So much what you said is wrong. But I'm just going to do the gears thing. According to the manufacturers. Lower gears tow more weight. Its just a fact. IF you will look at ANY of the ratings, You will see that a F150 with a 5.0, and 3.08 gears, is rated to tow far LESS than the same truck with a 5.0 and 3.73 gears. there are literally thousands of pounds different. So. According to the people that develop, design, test, build, and rate the capacities. Lower gears still mean as much as ever. And yes. I'm going with them.

As for towing a speed boat or TT. My Tt does either equally well. I don't need a 2500 to tow a TT in the less than 7500lb range.

Respectfully, nothing I said is wrong. If you do a spreadsheet of final drive numbers based on current 6 and 8 speed transmission ratios paired with numerically lower differentials vs older 4 speed transmissions and numerically higher differential ratios, you will find the newer combos have a more favorable 1st gear crawl ratio as well as more options for keeping the engine in the power band even with the numerically lower differential. So indeed the differential gear ratio is less important than it used to be. You used to have to choose between towing and economy because of the 4 speed's limitations. Now you get both in one. In fact some vehicles now do not have an differential gear option. One of my engineering courses was all about gears. The numerically lower differential will have a little bit higher gear tooth face force and thus a little bit higher friction (we are talking about a few percent here). If the axle ratio is the ONLY difference between two trucks, and Ford wants to use this slight difference to justify a substantially lower tow rating, that is up to them. Mathematically, there is no reason to, marketing wise, whatever.

As far as towing a speedboat vs TT and payload, I was speaking SPECIFICALLY to Ram and stated so. If you look at the payload numbers for current generation Ram 1500 trucks, they bear this out. If you are looking at towing any substantial travel trailer with a RAM, you should be looking at their 2500. :)

PUCampin wrote:

Terryallan wrote:

PUCampin wrote:
Axle ratio is A LOT less important than it used to be with todays wide ratio 6 8 or 10 speed transmissions. Crawl ratio with a modern 6 speed and a 3.21 is better than the old 4spds with a 4.56. The gears are closer spaced making it easier to keep in the power band. Given a choice, the 3.92 is better and will be more enjoyable, but a 3.21 is not a deal killer like it used to be.

Payload is the biggest issues with half tons, especially Ram. A few years ago Ram changed their general design philosophy to aim more squarely at the demographics. The vast majority of 1500 buyers want a nice car with a big trunk to carry awkward items and maybe to tow the jet skies or the bass boat to the lake. Most people looking to tow a RV were looking at 2500. So they softened the ride and added amenities to the 1500 to aim for the biggest audience. The result is if looking at a Ram and planning to tow anything bigger than a speed boat, you should be looking at a 2500. That is what Ram intends, but unfortunately most salesmen don't know or understand this and just want you to sign on the line.

Hmm. So much what you said is wrong. But I'm just going to do the gears thing. According to the manufacturers. Lower gears tow more weight. Its just a fact. IF you will look at ANY of the ratings, You will see that a F150 with a 5.0, and 3.08 gears, is rated to tow far LESS than the same truck with a 5.0 and 3.73 gears. there are literally thousands of pounds different. So. According to the people that develop, design, test, build, and rate the capacities. Lower gears still mean as much as ever. And yes. I'm going with them.

As for towing a speed boat or TT. My Tt does either equally well. I don't need a 2500 to tow a TT in the less than 7500lb range.

Respectfully, nothing I said is wrong. If you do a spreadsheet of final drive numbers based on current 6 and 8 speed transmission ratios paired with numerically lower differentials vs older 4 speed transmissions and numerically higher differential ratios, you will find the newer combos have a more favorable 1st gear crawl ratio as well as more options for keeping the engine in the power band even with the numerically lower differential. So indeed the differential gear ratio is less important than it used to be. You used to have to choose between towing and economy because of the 4 speed's limitations. Now you get both in one. In fact some vehicles now do not have an differential gear option. One of my engineering courses was all about gears. The numerically lower differential will have a little bit higher gear tooth face force and thus a little bit higher friction (we are talking about a few percent here). If the axle ratio is the ONLY difference between two trucks, and Ford wants to use this slight difference to justify a substantially lower tow rating, that is up to them. Mathematically, there is no reason to, marketing wise, whatever.

As far as towing a speedboat vs TT and payload, I was speaking SPECIFICALLY to Ram and stated so. If you look at the payload numbers for current generation Ram 1500 trucks, they bear this out. If you are looking at towing any substantial travel trailer with a RAM, you should be looking at their 2500. :)

Again. I'll got with the engineers that set the capacities. Otherwise. What would be the reasoning in making different gear ratios. And as a gear maker. I can tell you. there are a lot of different gear ratios. All designed to make a certain engine, and transmission work better together. I make gears from the high 2s, to the low 4s. And all in between.