I'm looking to buy a used fleet Cascadia in August. I'm set on a DD13 and 10 Speed. I drive at nights usually starting my day 22:00-00:00 and typically cruise at 60-61mph but I want the torque capability of pulling hills without dropping down to 50mph like I do in my company truck (International, Cummins, 10 Speed, no clue on gear ratio). I will typically be running southeastern states from VA to FL and out west to Texas. I've tried researching gear ratios and it's nothing but mixed opinions when it comes to fuel economy. I figure I wouldn't suffer from a higher gear ratio since I cruise at 60 and can still pull hills.
You’ll be fine with 3:55s, 3:36s, 3:04s, anything in that range. Also will depend on your tire size. Running 24.5s high rubber or lo-pros, 22.5s is most likely what you drive. So work your ratios in alignment with that.
I have 336 gears wish I had lower gears. Like 355 or 370. Most fleet trucks are high geared. Running tenth gear at 60mph you are going to have to down shift to ninth constantly to pull any kind of hill.
Would a 12 or 13 speed automatic be beneficial then? I've seen fleet trucks on TruckPaper with anywhere from 2.28s to 3.78s.
Do gears really make you climb a hill quicker? In my mind its about the HP/TQ. Eg: 0.79 OD ratio x 3.55 rear = 2.80 reduction 1.00 dir ratio x rear 2.69 = 2.69 reduction Basically the above is saying a 3.55 rear with a 0.79 transmission OD ratio is pretty darn close to a 2.69 ratio with the transmission down 1 gear into direct (or running top gear in a direct drive transmission). The deciding factor with how fast you'll make it up the hill would be the power out of the engine.
