Gear Ratios: Misinformation at its worst.

Lets say we have 2 identical trucks except the transmission.
The numbers are for demonstration purposes only;
Truck 1 has .90 and .80 overdrive gears.
Truck 2 has .80 overdrive only.
Do both trucks have double overdrive is the question?
Mechanically -NO
Theoretically- YES
I think that's where the problem lies. Different solutions for different scenarios.
When you start figuring in all the other components of the drivetrain you get different answers to the solutions, different strokes for different folks.

 

You're leaving out the auto crowd, and the BS sold to companies about how this gear will save XXX fuel and the driver won't notice the power loss, of course that assumes the driver has the IQ of a tumbleweed. I have this argument all the time with my bosses, I've gone from 3.92 to 3.55, because that's what the genies at KW said would get the best return, sure, until you're grossing 78K trying to climb Vail/Eisenhower/etc. and barely doing 18 mph, and being trying to get out of your own way, while the company is asking what's taking so long, but hey, by god, you're getting 8.3 mpg on the flats at 75 mph

 

I once was listening for the comedy factor.
He went into explaining tire aspect ratios.
Almost choked because of the laughing.

 

Link, please.

 

I would doubt it...... doesn’t fit in with the less is more mindset......


Think about the extra energy to spin the bigger shaft and u- joints......

 

What leads you to believe it was the rear gear ratio?
3.92 to 3.55 with a lower transmission gear is the same. or close.

 

Some of the problem is that MX I’d bet......

 

Are you saying rotational mass wastes energy that could be used more efficiently?

 

To tie these together, the last three trucks they have bought, that I was the sole driver, '09 Mack CXU MP8, 450 hp, Autoshift 3.92 gears, '15 CXU Pinnacle MP8 450 hp, 3.73 gears, M-Drive, '21 T680 450 hp, KW Autoshift, 3.55 gears. With the '09, per the guard dog system, for the LOV, it has a 5.5 mpg, for 630K miles, the '15, per the guard dog, for the LOV for 535K it was 5.9 mpg, the '21 my current estimated LOV MPG at 72K is 7.7. Now admittedly the T680 is much more aerodynamic, but I'm hauling the same trailers, over the same terrain, in the same conditions. We have a customer in Montrose, Co. that loads scrap metal, typically we are at 78,000 lbs, with the '15 Mack, I could climb Vail/Eisenhower/Floyd EB and stay in the 25 mph to 30 mph range, with this KW, I'm struggling to maintain 20 mph pulling those same grades.

 

If he has an MX trying to run at a higher rpm (1500 and up) to maintain speed on a hill is useless. You can watch your engine load and torque gauges and see that at a higher rpm all you’re doing is making more noise. For what I do I love the MX, but I wouldn’t want one for pulling weight in the mountains.

Edit: Just saw he has the 455/1650 version and I wouldn’t even want that for doing what I do. Lol. The 510/1850 version may suit him a little better but he might not be at 7.7 mpg with it.