Boy, what a process. The thing about getting a truck built is, there are things you want but cannot have, and things you don't really want but have no choice. Once you figure this out the project becomes easy, not simple by any means, but easier.
One of the first things to learn is to let the truck owner do most of the thinking; the driver gets to have his say somewhat. What I mean by this is there are two people inside each and every owner/operator, the owner and the driver. The owner doesn't want to spend any more than he has to get the job done efficiently and economically. The driver wants all the bells and whistles, no matter the cost. So the owner HAS to win this battle, with some concessions to the driver.
So what did this owner want? Efficiency, aerodynamics is the first link in the chain. Cascadia; this truck has shown to be one of the best, if not the best, in this area.
Engine? DD13, the 12.7 liter is the engine of choice after the tour we took earlier of the Detroit Diesel factory. What horse power? What torque? Those are good questions, the most efficient is the least of both, kinda. That is what the owner is going to have, the driver will argue till he is blue in the face, more power more torque, but alas he will lose. Why you ask? Simple, according to a study I read a few years ago,( can't remember where) it takes about 180hp to keep an 80,000 lb truck moving at 55mph on flat level ground, and this study was done years ago. The mountains haven't gotten any taller and we are only moving half the weight, flat level no problem, mountains, we will still get to the top, maybe a little slower but over the top none the less. Result is 380HP 1450 ft lbs torque.
Transmission? Here's where we started the interesting part of the spec process. Since we were building a straight truck we needed to stay with a 113 BBC,(Bumper to Back of Cab), in order to get the maximum sleeper space (driver chose this option). The most efficient transmission is a direct drive, 1 to 1 ratio in high gear, not a lot of driven gears here. Well, the driver wanted an automated trans. as did the owner, the available automated transmissions in a direct drive were limited. With Detroit's new DT12 the choice here was clear, DT12-DB-1450, a 12 speed direct drive with a 1450 lb torque rating.
Rear Gears? What ratio will be the best? A few things to consider. What speed do we want to cruise? What is the best RPM for the engine? What tires will we have? We know the trans has a final ratio of 1 to 1 so no question there. Now to begin the calculations. Knowing that every one MPH over 55 costs .1 MPG in fuel economy. The driver wants to get out and cruise, at least run the speed limit. The owner buys the fuel so he's saying slow down, compromise at 62 MPH cruise speed. The engineers that designed this platform determined this engines optimum RPM is 1350 to 1375, for 80,000 lbs, so we can lower that RPM some safely because the pulling power of the DD13 will go down to 1100 RPM. We will cruise at about 1200. For what we have learned about tires we will go with low profile 22.5 wide base single drive tires. After filling in all the variables we now know the best gear ratio would be 2.50 to 1.
The truck will be a single drive axle leaving the trucks rating GVW at 33,000. We ordered the truck with a 12,000 lb capacity steer axle and a 21,000 lb capacity rear suspension, total cap. 33,000 lb. We did increase the spring capacity to 14,000 lb on the steer and put a 23,000 lb wide track axle housing in the drive location, the heavy duty wide track axle will allow us to use the wide single tires without worrying about axle flex.
Here is where we are now, truck; Freightliner Cascadia CA113 day cab, engine; DD 13, 380 hp 1450 torque, trans, DT12, gears; 2.50, tires; Michelin 445 50 R 22.5 XOne Line Energy D drives and 275 80 R 22.5 XZA 3+ steers, all on Alcoa LVL ONE aluminum wheels.
We have the fuel mileage spec's done and the Freightliner computer programs are with us, for that part. One thing we want is the safest vehicle on the road possible. Disc brakes are the best choice for shorter stopping distance, lower maintenance costs, and by some reports, longer lasting wear parts. Bendx ADB22X-V was recommended for both axles, done. Some safety items people don't think about we will have are the Wabco Onguard Collision Warning, Adaptive Cruise Control , and Collision Mitigation. Enhanced Stability Control, and a Lane Departure Warning System to name a few.
We all want this truck to ride like the proverbial Cadillac. We started with air ride rear suspension and a spring ride front. The frame is another ride area that most don't consider. A double frame adds weight but it also adds strength and stiffness. Now you would think stiffness is going to make for a rougher ride, but here is the explanation I got on this issue. Take a thin piece of wood (single frame), fasten it at each end as if the axles were there. Imagine hitting a large pothole at road speed, the weight of the truck between the axles will flex the frame (the wood) downward, then it will rebound, most likely higher than it's neutral position and repeat this until it settles into normal ride or you hit another bump. Then take another thin piece of wood, glue it to the other one and try the example again, you will find the double frame (wood) will still flex downward but it will not rebound as far or as many times, the result is the frame will settle quicker with little or no back slap, a better ride. The double frame will not twist as easily, so going thru the gutters into a drive you will not get the amplified twisting at the top of the truck cab. We can sacrifice a bit of weight for a better ride, owner happy, driver happy.
There are a lot of nice standard features with the Cascadia, extra insulation (for sound and temp), good seats, a good gauge package and many things that you would not think about. We both (driver and owner) wanted to upgrade a few things for comfort and to better monitor the truck systems. We opted out of carpet in the cab so it would be easier to keep clean, we went with an Isringhausen Premium, Ultra Leather seat with armrests and the seat will swivel. The dash was changed to include gauges for the trans, drive axle, turbo boost pressure, brake application, and suspension pressure. Also upgraded was the look, a wood grain dash was installed. Driver very happy, owner, since the cost was minimal, ok with it.
Ok the truck is finished, but we have no place to sleep. The Cascadia has a factory sleeper that is comfortable but does not offer the amenities that we need for the time we spend away from home. The sleeper will be what is considered a custom sleeper. It is not offered by Freightliner so it will be added after the truck arrives to the dealer from the factory. Our sleeper will be built by Bolt Custom Trucks in Ft Wayne, In.. 100 inches of comfort, structural integrity and beauty. We went to Ft. Wayne to meet with the owners of Bolt about our sleeping and living space. The layout of the sleeper was efficient and functional, utilizing all space the best way possible for storage and livability. The only changes we made were to add a water heater and the Espar heater. This sleeper has a Dine-a-bunk, a bed that folds up against the back wall and turns into a dining area that will seat four. A large refrigerator/ freezer, sink with hot and cold running water, closet and cabinet space exceeding what we had before. Hardwood laminate floor, Formica countertops, and a combination of vinyl and cloth interior walls and ceiling make this a great place to come "home" to. All this was designed and built to give the durability and ease of cleaning one would expect in a custom built product of this quality. Deciding what type of auxiliary power the sleeper would use was an argument between the owner and the driver, the driver won, because the owner saw the value. The final decision was an Onan generator and inverter with a roof air conditioner. This unit will supply all the power needed economically and is shore power capable. The driver was extremely happy, as was the owner.
The cargo box was next on the list, we need to have the largest box possible, keeping the truck at or less than the maximum length for a straight truck of 40 feet. The frame was measured and a 22.5 foot box was chosen. We went with Supreme for the box supplier. We added some extras like, stainless steel rear door surround, stainless steel hinges on the doors, all stainless steel door latching hardware, six rows of E-Track, D-Rings in the floor, LED lights inside and out, plywood lining and scuff plates.
Ok, we have the truck and the box, are we ready to go to work? Not yet. A Palfinger liftgate will be added once the rest is ready to roll. The cargo box is just as it implies, for cargo, but we carry our personal stuff also, so we needed a place to put it. Bolt Custom Trucks will do the honors with custom boxes and aerodynamic skirting. Onspot automatic tire chains will be fitted by the guys at Onspot, for winter driving security.
We will install a tire pressure monitoring system, still undecided which one, to help with tire maintenance and we wanted peace of mind while running the wide singles. A Safety Vision camera system will help with backing, blind spot, and security.
Well I think that is the build of our new Cascadia, I'm sure I forgot some things but that is the idea behind the new truck. In the end, I’m sure we will all be happy with how it looks and performs. Thanks for allowing me to ramble, Bob the driver, Robert the owner.
Until next time be safe.