Curbside Classic: GMC TDH-4523 Transit Bus

Paul Niedermeyer
by Paul Niedermeyer

GM has built some great vehicles in its day, but nothing can top their buses. They literally owned the bus market from the forties through the seventies, but they earned that spot with superior technology and quality construction. One of the most brilliant and enduring examples of that is the “New Look” transit bus that came out in 1959, and revolutionized the field with advanced stress-skin aluminum construction and absolutely indestructible build quality. These buses are still on the road in transit duty fifty years after they first saw the light of day. A variation of this bus (the Classic) was still being produced by MCI until 1997. Given that this pictured bus was built about the same time as the 1978 Cadillac Eldorado in our last Curbside Classic, we have here a study in GM contrasts. Of course, even GM’s bus business eventually ended badly in its inimitable way.

I’ve been a lover of buses since way back, and I have a slew of bus books in the closet. We can’t do a proper survey of the genre here, but the GM buses tell a disproportionate share of the whole story. Let’s just say that transit (and over the road) buses were a pretty big business back in the day when there weren’t more cars than driver in the US. GM’s involvement in the industry dates back to the pre-war era, when they bought Yellow Coach company. And their involvement in dismembering LA’s superb light rail system after WWII in order to sell more buses is not a very pretty story.

But their buses were unimpeachable. The sort-of modern story begins in 1943 when Yellow was fully absorbed into GMC Truck & Coach. These post war buses were durable brutes, powered by GM’s legendary Detroit Diesel 6-71 2-stroke diesel engines. And GM Division Allison’s V-Series automatic was a revolution in itself. Try to imagine shifting a transit bus, double clutching every shift of the four speed un-synchronized transmission with a 40′ mechanical linkage! Shifts were extremely slow and arduous. The Allison was the greatest thing that ever happened to bus drivers.

The breakthrough modern bus was GM’s over-the-road coach PD 4104 from 1953. (This one was still hard at work in 2005 in Brazil). The construction of the 4104 completely broke with the traditional truck-type ladder frame, and was built more like an airplane with aluminum stressed-skin construction. It dramatically reduced weight, and made for an extremely rigid and solid structure. Buses have never been the same since. And 4104s are still desirable RV coach conversions.

The 4104 powered by the DD 6-71 and the manual transmission (not so painful for over-the road use) could get up to 12 mpg. And of course, it spawned the legendary 4105 Scenicruiser. That was specifically designed and produced for Greyhound, and curiously, unlike most of GM’s other buses, suffered from some structural problems. The complicated twin-engine (two 4-71 four cylinders) setup was also problematic, and were later rebuilt with a single 8-71V engine. But they were impressive sights in their day, and I remember some memorable trips in them.

GM’s New Look transit buses used the construction techniques that the 4104 pioneered. The benefits were manifold, but none more so than for the driver. Visibility was beyond superb; it was like sitting in a green house compared to the “submarine” predecessors. And the steering was substantially lighter because of the lower weight. Note that power steering on these was highly optional; the power came from well developed arm muscles and the leverage of a large wheel and a high (numerical) steering ratio.

The Allison VH transmission was a god-send, but a curious affair. It had all of…one speed. It was really just a torque converter with a massive amount of hydraulic effective gear range. On take-off, which was (in my case) always with full throttle, the engine spun up to full speed, and the bus would lumber away. Depending on vague factors beyond anyone’s apparent knowledge, at some speed of around 30 or 35 or so, the torque converter would be mechanically locked (with a substantial jolt), and now the engine was in direct drive. Depending on rear axle ratio, the transit buses could muster about 55 mph or so; the lower (numerical geared) Suburban versions maybe 65 on a good day.

I drove for Iowa City Transit in 1975-1976. There were 12 of the smaller 35′ long and 96″ wide buses like this one, and two of the TDH-5304 big boys: 40′ long and 102″ wide, and with the bigger 8V-71 engine. The 35 footers were pretty nimble compared to the forties, and one could whip them about pretty quickly in some of the older narrower streets of town. But the slightly newer 40 footers had one other nice feature in addition to the bigger engine: the throttle pedal was air actuated, instead of the mechanical linkage of the older buses. Not only did the mechanical linkage engender knee-ache (to go along with the back ache from the mechanical steering), but one jammed up on me one memorable day. E-pedals were still an engineer’s dream.

The bus in the upper photos has been converted by an enthusiastic Oregon Ducks football fan for game day parties in the parking lot. It also has a smaller non-stock steering wheel, which makes me suspect it has power steering. The other bus, an old left-over from Eugene’s fleet of these 4523s is the victim of a botched conversion attempt, not an uncommon thing. How compelling it is to buy an a tired old transit bus with millions of miles under its belt to convert to the ultimate get-away vehicle. Some have the resources; others don’t, as these two variations of the theme illustrate graphically.

I’ve been tempted to go down this road myself, especially with a handsome PD 4104 conversion. But it’s probably a good thing I’ve resisted, since I like to take my little Chinook in places a 35′ bus would never get out again. But whenever I see one, it does tug on my heart.

I got distracted on RV conversions, and forgot to talk about how GM’s bus hegemony fell apart. It fell victim to the same factors (and others) that undid its car (and big truck) market share: sinking reliability caused in part due to government influence. Since the feds fund the overwhelming share of all transit capital expense (but not operating costs), they started meddling early on with the bus designs themselves. The biggest one was the Transbus project to develop a new generation of buses in the seventies. GM’s proposal for that ill-fated boondoggle evolved into the GM RTS bus.

I’m not exactly an expert on this, but it arrived with complications and issues, unlike the New Look buses. The Canadians (wisely) wanted no part in this new generation of buses, and kept the New Look in production for decades. The RTS had a very checkered career, and eventually GM got out of the transit business, selling the RTS design to MCI, which eventually passed it along again. It was an unloved child that ended up in four foster homes before it was finally surpassed by newer and more desirable designs.

Greyhound never got over its problems with the GM Scenicruiser, and got into bed with with MCI, which has built almost all Greyhound buses until recently. And Trailways had a long love affair with the legendary German designed Kassbohrer that became the American Eagle. GM’s near-monopoly scared the two big bus companies into alternatives, and GM’s coaches eventually fell victim to a shrinking market and lack of development and conviction on GM’s part. Sound familiar?

More new Curbside Classics here

Paul Niedermeyer
Paul Niedermeyer

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  • Timbo64 Timbo64 on May 17, 2012

    Unfortunately, your info on the 35 foot suburbans isn’t quite correct. They were 4501 through 4504, not 35xx. The first two letters of the model designation was nominal seating capacity. You're right, I never noticed that I typed the wrong information. That mistake was mine, not John Mckane's.

  • Timbo64 Timbo64 on May 17, 2012

    Unfortunately, your info on the 35 foot suburbans isn’t quite correct. They were 4501 through 4504, not 35xx. The first two letters of the model designation was nominal seating capacity. You're right, I never noticed that I typed the wrong information. That mistake was mine, not John Mckane's.

  • Mike Audi has been using a3 a4 a5 a6 a7 a8 for a long time and i think it makes sense. But, they are rumored to be changing it all again within a year ir two.
  • Golden2husky Match the tool to the job. This would be ideal for those who have dreadful, traffic filled commutes. I'd certainly go the SE route - wheel sizes are beyond bordering on dumb today and 17s are plenty. Plus the added mileage is a real advantage. I would have been able to commute to work with very little gas usage. The prior Prius' were dreadful to drive - I gave mine back to the fleet guy at work for something else - but this seems like they hit their mark. Now, about that steering wheel and dash design...No mention of the driving aids for improving mileage but I'll assume they are very much like they were in earlier models - which is to say superb. A bit of constructive criticism - on a vehicle like this the reviewer should really get into such systems as mileage is the reason for this car. Just like I would expect to see performance systems such as launch control, etc to be commented on for performance models.
  • Arthur Dailey Rootes Motors actually had a car assembly facility in Scarborough ( a suburb in the east end of Toronto), during the 1950's and early 1960s. It was on the south-west corner of Warden and Eglinton located at 1921 Eglinton Avenue East. The building still exists and you can still see it on Google maps. That part of Scarboro was known as the Golden Mile and also had the Headquarters for VW Canada, and the GM van plant.Also at 2689 Steeles Avenue West in Toronto (the south east corner of Steeles and Petrolia) is what is still shown on Google Maps as 'The Lada Building'. It still has large Lada signs and the Lada logo on the east and west facades of the building. You can see these if you go to the street view. Not sure how much longer they will be there as the building just went up for sale this month. In Canada as well as Ladas and Skodas we also got Dacias. But not Yugos. Canada also got a great many British vehicles until the US-Canada trade pact due to Commonwealth connections. Due to different market demands, Canadians purchased per capita more standards and smaller cars including hatches. Stripped versions, generally small hatchbacks, with manual transmission, windows, door locks and no A/C were known as 'Quebec specials' as our Francophone population had almost European preferences in vehicles. As noted in previous posts, for decades Canadian Pontiacs were actually Chevs with Pontiac bodies and brightwork. This made them comparatively less expensive and therefore Pontiac sold better per capita in Canada than in the USA.
  • Ajla As a single vehicle household with access to an available 120v plug a PHEV works about perfectly. My driving is either under 40 miles or over 275 miles. The annual insurance difference between two car (a $20K ev and $20K ICE) and single car ($40K PHEV) would equal about 8 years of Prius Prime oil changes.
  • Ronin Let's see the actuals first, then we can decide using science.What has been the effect of auto pollution levels since the 70s when pollution control devices were first introduced? Since the 80s when they were increased?How much has auto pollution specifically been reduced since the introduction of hybrid vehicles? Of e-vehicles?We should well be able to measure the benefits by now, by category of engine. We shouldn't have to continue to just guess the benefits. And if we can't specifically and in detail measure the benefits by now, it should make a rational person wonder if there really are any real world benefits.
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