The 545 isnt a world beater by any means, but it IS a fairly decent tranny for when it was developed, and for WHAT it was designed for (there. I said it). Many tens of millions of miles have been logged hauling school kids around with them, and they appear in all sorts of medium duty trucks. You dont get this kind of market penetration if you are building an Edsel. The 545 really isnt "bad". But it is old technology and getting long in the tooth. And its not made for pulling hills all the time in a 30k GWV bus.
Many of the people who roundly decry the 545 as "junk" have never owned one. Or if they did, they got it with the bus (at auction, with its socks down around its ankles) and it had 200k miles of wear. And then they refuse to use the correct, current generation fluid, they crank-up the injection pump, and then take it out on a hilly banzai run in the middle of summer without a cooler. And they wonder why there are troubles.
The truth is, its not a bad tranny. And if you have one, you would be well-advised to read the Allison service bulletins and learn to drive it and maintain it properly. It isnt idiot proof, and it does not suffer shock loads well at all. But it WILL perform to the nameplate values with basic care.
A fact I recently learned from a retired Allison engineer: full pressure on the internals (bands) doesnt occur until the input shaft hits 2400 rpm. If you run slower than this, the trans is slipping under load and under a heavy load the result is predictable. Many school districts in hilly areas found this out the hard way when they ordered taller rear-ends and set the rev limiters at 2300 rpm thinking they would save money on fuel by "better using" the torque curve instead. Those districts wrote a lot of checks to transmission suppliers.
I'm looking at upgrading from a 545 to a 643 or 3060. Not because there is anything wrong with the 545, but rather because I want a locking torque converter and something I can flog in the hills without cringing. And a couple hundred RPMs less at 60 mph would be nice too.
Otherwise I'd happily stick with the 545 and call it good.
Back to the article referenced: we dont know what happened there, but if you havent mastered basic bus dynamics, that could indeed be you. So take the time to train yourself how to drive a bus, to stop a bus, and to maintain a bus before you get too far down the road. Some accidents arent avoidable, but most are.
End rant.
