Ever see a bus pole vault? Neither have I, but I did see the aftermath.
Our Scenicruiser was at warp speed on an interstate when the bolts assigned to holding the drive shaft to the differential failed.
The front end of the shaft dropped, slid on the highway just long enough to dig in, and launched the bus’s derriere skyward. As it lifted off, the weight of the entire rear of the coach was concentrated on the aluminum bell housing, which was not up to the task and cracked.
The bussy buttocks crash-landed back on the highway, and the Scenic rolled to a stop, sort of dragging the transmission under the body.
There are a couple of lessons here. When manufacturers spend precious dollars on a part, they think it’s important.
When GM built the Cruisers it added a “metal band thingy” under the drive shaft to prevent this sort of event — sorta like suspenders keeping your pants from falling down.
Somehow between the bus’s birth in 1956 and the 1971 pole-vault, the “thingy” had gone missing.
My experience is that lots of “thingys” disappear between the time a coach is built and when it goes to that big junkyard in the sky. They’re usually parts that are removed to get at components, like belt covers, electrical box doors, and access panels.
We repaired an overheating bus one time, and apparently the last guy to work on it was too hurried to put that pesky shroud back on. How much difference could it make? (About 30 percent.)
Like most of us, manufacturers are cheap and don’t waste materials, so if they put something on your coach it usually improves safety or reliability. It’s probably worthwhile taking the time to put it back on.
But the big lesson had to do with fasteners. Did you know they make bolts in different grades? I didn’t, at least when I was bolting up that drive shaft.
Holy cow, who knew that a grade 8 was MUCH stronger than a 5? Surprise.
Another thing we did to “save” money was to reuse bolts. There are lots of spots where it is OK, but if those jewels are taking a beating, bear in mind that every time you crank one tight, you’re stretching it. They’re never again going to be as strong as the first time you torqued them.
One time we replaced a 4104’s damaged differential with the pumpkin from another model bus. Bolted right up. Turns out it had a different ratio – a lot different.
That bus shaved hours off trips, and topped out at 85 mph. The drivers were happily clueless because the speedometer ran off the gearbox and only cared what the transmission thought. Heck, the sonic boom at an indicated 65 should have offered a hint.
This was about the same time that our boss got a great deal on new tires. They were really cheap, until we read the fine print stamped into the sidewall, something about never exceeding 50 mph. They were transit tires.
We salvaged a set of wheels from a burned bus and got almost 1,400 miles before noticing that they were cracking around all the lug nuts. Apparently toasting a wheel changes things.
Parts are a complex segment of our industry, and in light of this column, you’d be silly to take advice from me. It might be smart, though, to work out some guidelines.
What applications demand OEM parts versus aftermarket? When is it acceptable to reuse parts or fasteners, and are your people knowledgeable about what types of components can be reused? Can they tell a good widget from a bad one?
It’s probably wise to insist that your technicians reinstall those irritating “thingy’s” so that bus belts don’t eat fingers, electrical panels don’t inhale crud and drive shafts stay in the right zip code.
Little things can make a big difference. Buying from a sketchy aftermarket source may save money initially, but can cost a bundle if the part fails early.
On the other hand, some aftermarket suppliers provide parts that can be superior to OEM. GBBs (Great Big Buslines) have people who study those things. You may be able to learn from them, but at the least, you want to give thought to the whole process.
Fasteners are more critical than you’d think, and there are suppliers of varying quality. Be careful which ones you choose because these are not commodities, but components. Price is only part of the equation.
Parts aren’t sexy or visible, but they have a huge impact on our success.
If you think we were “thrifty,” consider the guy who used to go through our trash looking for useful parts. When we rebuilt an engine the liners were not tired, they were comatose.
This gentleman would retrieve our discarded liners and pistons, polish them a bit and “rebuild” the engine in his bus.
Dave Millhouser is a bus-industry marketing consultant and freelance writer. Contact him by email at Davemillhouser@gmail.com.