Originally Posted by "the_experience03":3ak266ug
Get something with a turbo, a retarder (you can find them on AT545's, but more commonly on MT643's) or a manual transmission, and air brakes. Going up isn't what I would be worried about..it's going down that I think could be problematic.
For this exact reason I would NOT want a transmission retarder! Long mountain descents could easily overheat your transmission fluid if you use a transmission retarder for long periods of time. All that energy it's absorbing is being turned into heat, and lots of it. Transmission retarders are good for around-town use, when they would be used for only a few seconds at a time. Even a huge external transmission fluid cooler may not be enough to keep the fluid cool enough coming down a long grade.
What would be ideal is a Telma retarder instead. They work by generating a reverse electric force, sort of like a diesel locomotive's dynamic brakes, and all the heat they generate is dissapated into the air flowing under the bus. Their only downsides are that they may need a shorter driveshaft, and they draw a lot of power off the vehicle's electric system so your alternator must be able to handle it. There are two versions, one "stand-alone" and one that attaches to the differential - one is called Focal, but I can't remember which one! You're right in saying plenty of Colorado buses use them - there's an interesting site of a converted Thomas Transit Liner (called Hormone Derange!) from Colorado which has pictures of its Telma.
I understand that some view this as a concern, but there are a LOT of commercial vehicles out there with retarders. If what you are saying is true, I think you would hear about WAY more issues with them. I am on a diesel forum quite a bit, and it doesn't even get mentioned. I just drove my bus from Idaho to Mexico and then back to MN with no problems whatsoever. I have an MT643 with a retarder and I LOVE it. I gave it a solid workout on the trip back and my tranny temp would always be cooler going down hill then up. 170* down hill was the norm, and these were many mile long 6-8% grades.
KeyserSoze, if I were you, I would look for a DT466/MT643 combo. I cannot say enough about how happy I was with this driving it cross country. Seriously, nothing ever hiccuped, not even once. The engines are also incredibly easy to work on if you needed to. I've had fun tinkering with mine (fuel, timing, governor...) I also have air brakes, which I would highly recommend. FWIW, I paid $1500 for mine. It's a '91 71 pass. international.