Time to buy a new semitruck, but not sure what brand

BahehahBawhah

 

It is not correct regarding modern powertrains. The manufacturers of the related products have come together to build systems that work.
An example. My truck is a 6X2 Direct drive. I have a beefier, driveshaft, yokes, knuckles, ujoints, and clutch capable of handling the increased torque load. If I were running a spec closer to 1998 levels, I wouldn’t need all that.
If you spec a downsped drivetrain with a dealer, their spec program will automatically put these things in the spec, it will not allow to select certain products because they can’t handle the stress.
I have a transmission temp and axle temp gauge, they never get hot. Even under long pulls. All the associated components have come a long way in recent years as downspeeding is taking over the highway market. As the truck bodies and engines have advanced so has everything else to support and cope with the changes. I think that’s something often overlooked or just not known. Even Daimler has a 2.16 ratio rear end capable of downsped applications with a direct drive and DD15 motor.
I rarely use full torque, if ever. I use a maximum of 25-27 pounds of boost which equals 200 hp in a 13l class motor, like mine. My average engine load is 33% according to the ECM.
Even the oils are designed around downspeeding. I’m running FA4 oil in mine for that reason. FA4 offers superior performance in downsped applications.

 

I’ll post a link from Spicer that explains it and how they engineer products to handle the increased stress. There are plenty of other things you can find from other manufacturers as well.

http://www.dana.com/~/media/danacom...le/cv-literature/downspeeding-white-paper.pdf

 

What about the crankshaft? Or these little things called main bearings?

 

Interesting, so what driveline are you running?

 

Yes we know they spec drivelines to HP that ain’t new . Carry on then

 

200 hp? Holy head gaskets No wonder you’re getting good fuel mileage. How much boost do you have to make to get 400 hp?

We’re not talking about averages. We’re talking about pulling a hill

 

I have the Meritor products on mine. I have the RPL35 drive shaft. When I specified the RPL35 it includes the supporting components for that torque rating, all Meritor. It is capable of handling over 21,000 ftlbs of torque. That’s not a mistake either, the driveline is capable of over 21,000 ftlbs. They aren’t spec’ing them to HP, they’re spec’ing them to the huge increase in torque load of downspeeding.
As far as the crank and main bearings the oil manufacturers have released CK4 and FA4 oils on the market that are designed with downspeeding in mind to protect these components. Manufacturers have also changed the materials used in constructing bearings and cranks and made them larger to handle increased stress and not sacrifice life. CK4 and FA4 have a considerably higher “sheer” strength over previous CJ4. This is to protect components in downsped applications. I’m running FA4 in mine because it has even better protection in this scenario as it can handle even more heat than CK4.
On a hill at a low rpm of 975-1050 when I normally shift, that would be between 50-55% engine load because I’m using 200 of my available 400 hp. I only use a max of 200 unless I’m trying to get out of a situation.

 

Still not gonna be a big believer in them, it's unneccesry stress on expensive stuff. How do you know it's only half your horse being used, the only way I know of to do that I wouldn't want to be caught doing while going down the road, could end up with a nice little distracted driving ticket or some ####.

 

I ran my ScanGauge in it for several weeks. I have a boost gauge in the truck but the ScanGauge will tell you how much horsepower you’re making. In a 15l it’s 20-22, 13l it’s 25-27, depends on the rpm.