What is up with the questions about gearing?

Does this make you a cryer?

Apparently I’m not good at following instructions

 

Rank, are you running a 15 direct or short rubber?

 

15 OD and lo pro 24.5’s. I forget what the OD ratio is on that old 15 speed..... .78 or .81 or something like that. It really needs a 13 or 18 but I can’t bring myself to toss a perfectly good trans

 

My 15 has more od than my 18, you need tall rubber with those 390's. A friend of mine had 15 direct and 342 rears or some soch thing, the gears were not too good on the haul road, so he regeared to 390, and with tall rubber and direct tranny, he had a 55 mph truck.
I run a 15 od and 529' in my log truck and am only 1700 at 55.

 

After careful thought I recall some of the older trucks, the early computer versions in the early 90's They would have very tall 10 speed fullers and contain rears with 55 mph gearing in them. Turn over a 2100 red line into a pig that wont do but 1600 all out at touching 60. The minute you touch a upgrade downshift you go. And watch her just fall down to hands and knees adding more downshifts. Once in a while you end up splitting to low range and continue to downshift as the radio lights up with WTF etc talk with you in the way.

Want to be in Columbus overnight from PA? Nope not happening. Not with those piles of crap. Wait all day for the engine to wind out each gear get to the next hoping you can stay above it and wind that gear out. watching that speed twitch slowly and lazy past 45.

I hope they either blew up those ####ty tractors or scrapped them to be made into vases or something. As a result of those bad days wrestling with those fleet trucks I developed a pernament distaste and hate for the company 10 speed transmission with any truck that starves fuel at 1500 when you should be able to wind it to 1950 You will never see it in those trucks.

That became a factor in selecting employment in trucking. Roast the recruiter in very pointed questions about the fleet. what they run, what they gears are and so forth. Recruiters hate me. One company ATS gave me a sweet little 330 or so early electronic Kitty cat on a 9.

I tell you what, as small as that little kittycat was it stands near the tops of trucks I prefer to remember with some joy. I managed to have that thing do things that would have probably broken other trucks. But ATS effed up seriously by just one 140 gallon fuel tank on there. Not for OTR work like I did. Fueling two to three times daily. It's disgusting.

6 months think about fuel and where to get more. Constantly. Like a begger on the corner wondering if he will get enough coins to get a hit of something good.

But it was not until much later in my life that I was issued 500 plus horse detriots and other engines that you DO NOT have to wind for nothing. Take your gear at torque and use it. When she starts to lug and buck, take the next one down. And that's all. Wait until you get the top. Big horse rules. Less work to lift weight over the mountain. Less fuel per hour burned doing it and on and on.

 

You forgot to mention speed and speed limits. Double nickel in Cali, or 80 in Utah?

 

Some of you will want to argue. But I see this 2 ways.

Low rpms. Less fuel burned. SURE. On paper. But let's not forget the powerband.
Engines might have torque but realistically. It requires more pedal in the lower rpm. Powerband requires less pedal in the higher rpm.

On the flat land. Low rpm could work. But not in the mountains.

It takes longer to climb a hill in the low range. That's more time spent at full throttle. A 500 horse engine could pull it off better then a 450 horse engine.

A good test run. For those of us that did it on a somewhat regular basis. Phoenix to Flagstaff.
The 05 w900 ISX450 I was driving at the time. Would do that drive 20 minutes faster and burn less fuel running the powerband range vs. the torque range.

The faster you can climb the hills. The less time spend with pedal to the metal.

Course, if you want to drive the KR method. I'm not sure if you'd save fuel or not. You might be stopping for pee breaks by the time you got to the top.

Which goes to the next note. Engine running time.
55 mph will save fuel over 65 mph. SURE. But how much longer is that engine going to run to get you from point A to point B?
Is there a gallon comparison chart for gallons used to drive 1000 miles? Flat land and mountains. 500 horses compared to 400 horses. Pulling 80k.

Everyone wants to save fuel. But realistically. Some operations don't stand much of a chance compared to aerodynamics pulling vans. Flatbeds and Heavy haul in the mountains and open wind resistance comes to mind. Although the 16 FL I drove did really good on economy compared to the earlier trucks I drove pulling flats. It also didn't require as much travel time.

 

No, just makes me someone who wouldn't drive a neutered truck or be micro managed.
Are you okay with that?

 

Omg, it is a rhetorical question.


Something to ponder about .... maybe prompt others to correct people's misconceptions about how a Diesel engine works and what to look for in gearing.





Here is my thinking .... for what it is worth ...


The problem with thinking that gear ratios is the only thing that matters is just plain wrong. Most are not looking at the drivetrain as a whole or take in account the engine and don't set the goal for gearing an engine to hit the bottom of the fuel consumption curve for cruising. Also no newbie is told to use the transmission to take advantage of the gearing when they need power, it seems the threads have answers about just gears and nothing else.

Snowy and a couple others know what I'm talking about but billyjoebob who is thinking a truck is just like a car and wants tall gears to lower the revs on the engine is clueless to how it works and may be disappointed with the results of a tall gear.

Revs do not equate to better fuel mileage that's a fact. Now a days the computer will tell the engine to over fuel if there is not enough torque or when the engine gets out of the power band.

It used to be peak torque hit at the bottom of the fuel consumption curve but with the electronics, that seems to have shifted peak torque a little bit on the high side near the bottom of the curve.

The selection of a transmission is very important, 9/10 speeds are great for those lazy newbies or someone who is tired of shifting but 9/10 speeds have too wide steps to actually be effective to get the best mileage out of a truck, to me they are for local driving. I found 18 speeds are the best, close ratio steps help with keeping the engine within its power band and closest to the bottom of the power curve.

Also to confuse matter even more is the engine size itself, the lower the size, the higher the bottom of the consumption curve in relation to rpm. The 15 l engines seem to have that bottom of the curve at 1100 to 1200 rpm where as the 13 l engines move that up 1200 to 1300 rpm.

 

Must be an early version 18 then.