Used TMC truck

[Rawze]

(07-25-2019 )Mattman Wrote:  3.36, 3.42 are about the lowest gears I have seen for the most part. Seen several 3.08 trucks. The automated trucks have 2 something gears in lots of them.

I have been looking for awhile, I am picky. Been looking at Paccar and Freightliner trucks.

I would not own a truck with those tall of gears. The truck struggles to get out of its own way at 3:42, nonetheless 3.36's or an even worse 3.08 ... those are terrible gear ratios for an 80,000 lb vehicle, especially in hills and mountains. Those tall gears also kill overall engine life.


3.55's are about as tall as I would ever want to see a truck geared that has to do actual work, with an actual competent driver in it.

3.70's are better suited, especially if your running all 48 states and /or go 65+.

3.90's if your regional and tend to drive below 65 or are like me and drive 55 - 60 everywhere because you want to maximize profit over all else. Maybe even 4.11's, or 4:36's if I were to haul anything over 80,000 lbs.

Just throwing the rough numbers around,.. everyone is different. -- All I do know though is that I have driven a lot of trucks, a person can tell the most when they drive samae make and model but very different rear ratios. I have also driven and compared many different brand, year, make trucks too.. and I can see the differences first hand. -- Trust me, those bulls%it taller engine killing rear ratios are not any good for people who haul any weight at all, or for those who know how to actually drive for high profitability.

I have finally figured out why the mega-fleeces prefer those tall engine killing gears....

Those tall bas$tard gears only suit the mega-fleets and their ignorant drivers that do nothing but hold a fuel pedal against the speed governer all damn day long. With this the case, it actually make for slightly better fuel mileage at the expense of engine longevity. Here is why...

When the engine is forced to turn much lower rpm's in general, in fact so tall that the engine hardly ever sees anything more than about 1400 - 1500 rpms ... it severely limits the overall useful horsepower output all the time at the expense of torturing the internals due to high torque and low rpms.

Take a truck that has a typical mega-fleet program in it, 1650ft-lbs, 450hp program ...

A truck climbing a hill at 1200 rpm because its geared too tall, and your in top gear against that speed governor with your foot ... that truck is only making 376 horsepower -- that is not a lot of power for getting work done, and does not consume nearly the fuel as say ...

The same truck, geared much lower, same governed speed, the engine would be turning say 1600 rpm. In this case, 1600rpm and 1650 trq , it would be producing 518hp going up that same hill .. It will also not fall flat on its face half way up the hill, engine making less and less hp as it does so -- hence more fuel overall consumed -- but you also did more overall work.

Looking at it a different way...

When the overall average HP of a truck that is set to 450hp - 1650trq ..governed at 65 mph .. with say 3.36 rears is roughly going to be driven its whole life with an average of about 127HP over a 500,000 mile span. Most of its life it will be rinning 1350 rpm or so against that speed governor.

Same truck, same governed 65 mpg speed, taller rears, lets say 4.11's (using an extreme to show the differences more clearly)... ... its whole life will average about 150HP (same exact math) over this same 500,00 miles span.

-- 500,000 miles of 127 hp vs. 150hp is a huge difference in fuel consumption. -- but at the expense of getting a lot less work done that is unseen. -- All the extra hours of climbing hills because the taller geared truck can't get out of its own way, therefore a lot more hours with less revenue after 500,000 miles due to all the lag. -- VS. all the extra work that gets done by the one with better suited rears, more loads and less lag in the 500,00 miles span == more profit overall in the same time-frame and miles consumed.

BUT IF YOUR ONLY LOOKING AT THE FUEL MILEAGE AND NOT THE WHOLE PICTURE--- It would always appear that the higher average hp truck is less efficient because of a lower overall fuel mileage average.. Hence the nega-fleeces and their tall-arsse geared truck these days. -- This leads to the question... Is the higher HP more profitasble long term,.. or the hp limiting gear ratio that forces less fuel consumption at the expense of less work being done...

Well,.. it comes down to fuel prices ... When fuiel prices are lower,.. the taller rears hurt the mega-fleeces more, because less loads get hauled vs the fuel that they saved. -- But when fuel prices are higher .. they loose if the truck is allowed to make more power because the fuel consumed out-weighs the work gains.

-- i say,.. become more flexible as an owner-op... gear it with the highest ratio you can use (like using 4.11's instead of 3.36's),.. and if you want to save more fuel by limiting your engine's overall HP --- LOWER THE HP RATING IN THE ECU .. you would see the same exact results,.. but without all the engine wear because it is at max torque all the damn time. -- BETTER GEARING IS THE ANSWER HOWEVER YOU LOOK AT IT but it must come with the discipline of DRIVING THE TRUCK THE RIGHT WAYS! instead of like a company moron.

It is overall HP that gets work done,.. and overall HP that consumes fuel,.. not the torque alone. <- make an engine able to make more HP, and it will consume more fuel, but also do more work.

Kill the engine's ability to make its full potential of HP rating (by making the gearing too tall to be useful), and you essentially dial out its ability to consume its full potential of fuel usage.

What you end up with once you put someone behind the wheel that actually can drive a truck without it being slapped against a speed governer all damn day is a truck that now will not get out of its own way for sh%$it,.. but also consumes a lot more fuel than necessary once the proper rps's are being used, because all the torque is lost in those tall damn rears. -- Re-gear the truck to a more reasonable 3.79's, and suddenly the thing pulls better, climbs hills without the thing in the floor all the time, the rpm is up where actual working power con be used, and the thing is overall more fuel efficient,.. that is unless the same company driver idiot still drives it like the fuel pedal only has 2 positions,.. then you will not gain anything.

-- In all reality, if the mega-fleeces wanted to save fuel so badly by limiting overall engine HP,.. they should have just gone back to lowering the engine power rating to 350HP, because that is essentially what they are doing by gearing trucks those ridiculously tall 3.08's and 2.79's and other stupid garbage. - At least this way, it would not be constantly torturing the engine, and it would still be more fuel efficient because of far less internal engine friction.

(rawze's rant for the day).. now where's my beer llol