Originally Posted by Nrfing
I'm new to the site, I've got a question that I cannot get a answer too. I bought my bus from a church. They told me they had installed a new pedal assy, which it is new. I run a constant 125psi of air, but it only does like 50 mph, and up hill is a real pain, no power really. I understand that it will be slow. But is this normal, down hill it'll run 60 65. Just trying to see if this is normal or if I have issues
Agree with Rovobay. First, you have to understand that a school bus / church bus is essentially a 12,000 lb brick. They are by nature underpowered on purpose. Most are in the 175-210 hp range. Torque is what does your pulling, horsepower is how fast it goes, and how fast it can reach a given speed. Very few of these will ever top 55-60 mph, and many will not like it if they do. Diesels are not made for higher rpm, and most buses are geared low enough that they may not even be able to reach 60 mph without risking damage to the engine.
A heavy vehicle like this is going to naturally succumb to gravity on hills. What goes up, must come down -- meaning gravity will slow it down greatly going up hills due to the weight, and that same weight will make it speed up greatly going downhill. Gravity and inertia at work.
First, it would help to know what you have. Manufacturer, chassis series, engine, trans (if you know what it is), and approximate weight / passenger capacity of your bus.
As far as a pedal being replaced, was it the treadle valve for the air brakes? Or was it some type of electronic pedal assembly for an electronic-controlled throttle. More info is needed on your particular bus in order to determine what, if anything, can be or needs to be done.
Sorry I can't be any more specific, but it's hard to say if your bus is perfectly normal or needs work without knowing what it is and how it is set up. One thing that is a possible factor here... I've seen it posted in this forum that North Carolina sets their buses up to be governed or max out at 50 mph. So if your bus came from North Carolina or was ever a school bus in NC, that's a potential and likely factor right there.