Question about axle Ratios

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.