This is a great thread. We all think that faster is better, when we need to travel several miles. I drive a LMC 3700C with asymm tracks in about 9 miles to a lodge. Pulling up hill is tougher and slower, because we pull a sled full of kids (about 35). It takes about 1 hour and 10 minutes. I think more hp would help to go faster up hill, but your points about driving over rough roads is well taken. The faster you go the more you beat yourself and the machine up. Driving over about a foot of power on top of packed snow is great, but that doesn't happen too often. Also, I go in on a snowmobile when I need to get in faster and cheaper. However, the bumps, dips, and uneven packed snow kills me too. A better suspension is only good if you go slow enough to let it work. Or maybe fast enough to only skip over the tops of the bumps. Lol. Also, faster speeds means that the tracks are trying to throw themselves away from the idler wheels and as some said, that results the tracks hitting underside parts. This is a result of centrifugal force, which gets greater the faster you drive. Basically, if you double your speed you have increased the centrifugal force by 4 times. Centrifugal force is actually related to the mass times the velocity squared, divided by the radius. So the speed at which you are driving is responsible for the force driving the tracks upward and is a function of the velocity squared. So if you are driving at 8 mph, the square of 8 is 64. If you are trying to drive at 15mph, that force jumps to 225 almost 4 times greater). That force is trying to throw the track off of the guiding system and drive links. That is why so many belt drive systems, like lawn mower decks and automobile belts added idler wheels, to counteract that force.
In the automatic transmission or hydraulic drive motor snowcats, do I need to worry a little about the temperature of the fluid. I recently purchased two Thiokol 3700s. They both have the Alis Chamers motors. I don't know which specific motor yet, I will need to look for some plate with the info or pictures that show the difference. If it a four cylinder motor, I am only seeing an AC 433 as an option. I don't know or remember if they have a temp gage for the hydraulic fluid to the drive motors, but I may try to install one if they don't.
Also, I need to look at the manual to see how to switch from high range to low range. That may help to keep the fluid cooler if it gets hot. So much to learn about these snowcats, but it is a lot of fun learning about these machines. I just finished replacing a few tires and wheel bearings. Now that it has started snowing I am about to go play with them in the snow to see what they do.
My wife was ready to shoot me for buying these Thiokols. Little does she know a person approached me yesterday asking if I might want to buy his 1970 Tucker snowcat. I know even less about Tuckers, much less what kind of condition this thing is in. However, I know me, so yes I will be going over to look at it.