Bus Stop Classic: GMC PD-4501 Greyhound Scenicruiser – Everybody’s Favorite Bus Except For Greyhound And GM

(first posted 12/24/2013)     How did the Scenicruiser become such an icon, undoubtedly the most-recognized bus ever built in the US? It’s safe to say that after the Scenicruiser made such an indelible impression on Americans in the fifties and sixties, every other bus was just…a bus.

After a protracted wait to see what the industry would come up with as the definitive new bus of the post-war era, the Scenicruiser arrived in 1954 as the herald of a new era, one that would redefine the genre and make riding the bus exciting again. Yes, the bar was set  high, but the Scenicruiser failed to clear it, despite the legacy of its instantly recognizable shape.

In 1936, GM’s Yellow Coach Division set the template for the modern American intercity bus with its Model 719 Super Coach: forward control, high floor with ample luggage space below, semi-monocoque construction including the use of aluminum alloys, air conditioning, and a rear-mounted engine (gasoline, at that stage).  At the time there were many small independent bus manufacturers, and with the Model 719, GM began its climb to dominance in the field.

By the time its replacement arrived in 1940, the PD-3751 “Silversides” (CC here), GM’s ground-breaking two-stroke Detroit Diesel engine was in full production (Birth of the DD engine here).  The DD 6-71 engine was compact, efficient, light and powerful (some 165 hp in its early versions), the perfect engine to propel buses into the diesel age. Its size allowed it to be mounted transversely at the very back of the coach, maximizing space efficiency. Since GM wouldn’t sell its diesels to its bus-making competitors–until forced to as a result of a 1956 anti-trust lawsuit–GM’s buses enjoyed a very distinct competitive advantage. This pre-war Silverside design, built exclusively for Greyhound, and its many other variations became the dominant bus of the immediate post war era.

Greyhound had also become the dominant nationwide interstate bus carrier already well before before the war, and there was considerable anticipation as to what the Greyhound bus of the future would be. In 1945, GM and Consolidated Vultee were each given development contracts for a post-war bus, but by 1946 both cancelled their contracts due to too much other work. They turned over their blueprints to Greyhound, which then went it alone, commissioning  Raymond Loewy to do the styling on a 50 passenger bi-level coach dubbed the “Highway Traveler”.

The GX-1 Highway Traveler was built in 1947 at Greyhound’s own repair and maintenance shops. It seated 37 passengers on the upper level and 13 below. The GX-1 was 35 feet long, then the maximum length allowed by virtually all states. That was the particular appeal of the bi-level arrangement, the only way to increase passenger seats within that limit. The GX-1 also featured a primitive version of air suspension.

The biggest challenge was finding a suitable power plant that would both be able to propel the tall and heavy coach at decent speeds up long grades as well as be economical on the flats. Powerful gasoline engines like the Hall-Scott had the first part of the brief covered, but were exceedingly thirsty. The DD 6-71 just wasn’t powerful enough, and there were no larger versions of the DD family back then. That led Greyhound to an unusual solution: twin air-cooled V6 engines from the Aircooled Motors Co., the successor to Franklin Motors and the source of the Tucker’s aircooled six. The original idea was that both engines would run on the hilly sections, and then one engine could be shut down on the flats.

Here’s some unedited footage shot of the GX-1’s presentation. The Greyhound executives are obviously proud of their new bus, but in reality, the GX-1 had a number of issues with that unusual drive train, as well as others. Greyhound was pioneering new ground, and it it wasn’t smooth going.

The GX-1 had a brief career in revenue service, but it was soon sidelined at the Greyhound shops where it had been built.

There it sat under a tarp, until it was finally scrapped in about 1955 or so. Time for Plan B.

The next version, the GX-2 prototype, was named “Scenicruiser”, and was a considerable departure from the GX-1. Although again styled by Loewy and built by Greyhound, this time GM Coach was much more involved in its design, development, and even its styling.

from a children’s book that I used to read to our kids

 Although the Scenicruiser would be exclusive to Greyhound, GM was in the early development of its next generation 35′ coach, and wanted to reap efficiencies from both projects.

 

GM even sent an unfinished 35′ PD-4151 bus shell to Greyhound, a starting point from which they created the 40′ dual rear-axle GX-2 Scenicruiser prototype. The Scenicruiser’s split-level configuration, with ten seats and the lavatory on the lower front compartment, and the additional 33 seats in the higher rear section allowed a very large luggage compartment under the raised section, and was generally a more practical configuration than the bi-level GX-2. But there was one big hurdle; or many actually.

The 1949 GX-2 was 40′ long, and almost all states had still had that 35′ maximum length restriction. Greyhound used the GX-2 to lobby for increasing that limit, a process that took several years. The film in this video was shot by the Oregon State Police, the GX-2 presumably showing off its maneuverability as part of that process that took several years.

Let’s take a brief diversion back, to consider the Scencruiser’s distinctive split-level design. It was hardly new or innovative; the oldest bus I can come up with that used a similar approach is this 1928 Pickwick Cherokee, which also placed the driver up high in his own compartment.

This 1937 Kenworth is even further along in the direction of the Scenicruiser. It used an under-floor lay-down engine, probably a Hall-Scott.

And this Brill built for Continental Trailways shortly after the war makes it clear that Lowey’s claim to have “invented” the Scenicruiser rather without merit. It was a 35 footer, and not successful.

In addition to the length restrictions, there was another hurdle to jump with the GX-2, the same one that the GX-1 had failed to clear: a suitable power plant. The prototype GX-2 used the DD 6-71, now up to some 200 hp, but it just wasn’t going to be up to the task of a fully loaded 40′ bus. GM used the GX-2’s limited revenue service to experiment with various solutions to soup up the 6-71. Different cylinder liners with bigger ports, high lift cams, and a higher operating engine speed were tried, but not considered satisfactory. A two-speed auxiliary transmission helped a bit further. The GX-2 was just underpowered.

 

GM took on the task of building the final production-version Scenicruiser prototype in 1953, now officially called the PD-4501, as a model for the 500 more that Greyhound initially contracted for. The PD-5401 was strictly reserved for Greyhound and along with a contract extension for 500 more, a total of 1001 Scenicruisers were built, including the prototype.

The production Scenicruiser shared much of its design and technology with GM’s next generation 35′ intercity coach, the legendary PD-4104. That went into production in 1953, one year ahead of the Scenicruiser, and was the first truly modern coach, with air suspension that dramatically improved passenger comfort. Its story should really come first, since it arrived ahead of the Scenicruiser and pioneered most of its styling and many features, but we’ll come back to it. The two were essentially co-developed, and shared much in common, except for their drive train and size.

Whereas the 35′ PD-4104 used the now-classic GM Coach drive train with the transverse 6-71 engine, a Spicer non-synchro four speed transmission and Vee drive to the single rear axle, GM came up with something unique for the Scenicruiser.

Twin DD 4-71 four cylinder engines were mounted longitudinally, side-by-side, connected together with a fluid coupling whose output was fed to a solenoid-operated clutch, a three-speed transmission with synchronized second and third gear, and a two-speed auxiliary transmission to split the gears, for a total of six gears. Drive was to the rear-most axle only.

Only one of the engines had a starter; the other would automatically be engaged via the fluid coupling after the first one started. Both fluid couplings fed into the transmission.

Because the clutch was solenoid-operated, it was essentially on or off, resulting in inevitably jerky starts and shifts, although presumably the fluid coupling would have dampened that somewhat. That was revised in 1955 with a mechanical linkage for the clutch, giving smoother starts. But unlike the legendary reliability of the traditional GMC drive trains in the 35′ buses, the Rube Goldbergian affair in the Scenicruisers quickly proved very troublesome and unreliable.

Greyhound was so deeply frustrated with the availability rate of the Scenicruiser that they actually shipped one to Germany, to have Mercedes install one of their diesel engines and test it on the autobahn. Take that, GM! Other problems were cropping up too, mainly structural ones in the area of the side windows above the rear-most axle. GM’s vaunted reputation with coaches was cracking, literally.

By 1956, Greyhound and GM were in a major tiff, trading barbs in the press, which escalated into a lawsuit. Greyhound never ordered another Scenicruiser after the initial batch of 1000 already contracted, and within a few years bought the Canadian bus manufacturer MCI. Greyhound had little choice but to buy some more conventional GM buses until it could source all of its needs from MCI, and then never looked back. This, along with the federal decree requiring GM to sell its diesel engines to its competitors after 1956 were the key turning points in the eventual decline and demise of GM’s intercity bus business.

A solution to the Scenicruiser’s power train problems, albeit an expensive one, arrived in 1959 when Detroit Diesel finally unveiled an eight-cylinder engine, the 8-71V, rated at 318 hp. Greyhound signed a pricey $10 million dollar contract with Marmon-Harrington to completely rebuild the whole drive train in its whole fleet of Scenicruisers.

The V8 diesel engine, still mounted longitudinally, now drove through a conventional clutch and Spicer non-synchro four speed gear box; essentially the same as the 35′ buses, without the vee drive.

The fleet of Scenicruisers also got a refresh of its interiors, and went back to work. The drive train issues were now resolved, but the structural ones continued to plague the big buses, requiring recurring patches. Greyhound was not pleased.

But the Scenicruiser captured the public’s attention and admiration, generating the kind of interest that a bus could only dream of doing today.

The Scenicruiser also inspired a lot of me-too competitors, the most blatant rip-off being this Beck DH-1040 from 1955. Only twelve were built, so I guess GM and Greyhound weren’t too worried.

Actually, Beck’s DH-1000, which appeared in 1950, was in production several years before the Scenicruiser. But Beck had a tradition of imitating GM coaches, and there’s little doubt that it was “inspired” by the 1949 GX-2 prototype. Beck was very quick about getting new models out the door.

Flxible also joined the party in 1955 with their Vistaliner, powered by a Cummins diesel. Trailways bought some, but eventually found their ultimate Scenicruiser competitor further afield: in Germany.

Trailways went shopping at Kässbohrer, the renowned maker of Setra buses. They specified a similar-sized 40′ luxury bus, the Golden Eagle. One key difference was that it had a continuous high seating area, and as such, the Golden Eagle was the true prototype of all modern tall-boy buses.  It even had a rear lounge and a hostess that served refreshments.

In 1958, Kässbohrer also delivered four articulated Golden Eagles to Trailways, but that turned out to be a bit more than Trailways could use economically. Amazingly, one is restored, and another sits nearby Eugene in Dexter behind the former Green Tortoise shops. Here’s the full story on this pioneering bus.

The similar Silver Eagle was a bit more down-scale. The first Golden Eagles were powered by a MAN diesel; a few were even tried with a Rolls Royce engine. Most Silver Eagles had a Cummins diesel. But when DD engines became available, the Eagles also switched to the 8-71V, which soon came to utterly dominate the bus market after GM was forced to sell them to other bus makers.

 

Eagle production switched to a Trailways-owned dedicated plant in Belgium in 1958, and in 1974 production was switched to Brownsville , Texas. The Eagles went through a number of evolutions and was made until about 1996. The Eagle was generally felt to have a better ride and more practical configuration than the Scenicruiser.

The Scenicruiser fleet went through several livery changes, and in 1970 another refurbishment that also saw a number of them converted to “Combi” configuration. These had a large rear cargo area walled off at the rear of the bus, of varying size, and a large exterior door on the right rear side. Greyhound Package Express was sort of the Fed Ex of its day, especially in more remote areas. I used to see these Combis still roar through downtown Iowa City regularly as late as about 1973 or so. But the rest of the Scenicruiser fleet went into storage and was increasingly sold off to private operators. The last ones operating in the new Greyhound paint scheme were some commuter buses in San Francisco up until 1975. The Scenicruisers were replaced by the MCI-7 and its later iterations.

 

So now that we’ve done the Scenicruiser history, let’s take a closer look at some. We’ll start with Craig Dickson’s finds in San Diego, where he stumbled into three Scenicruisers in various states. Some of his shots are in the article earlier. These two are huddled together for company; what stories they could tell.

The third one is sitting a ways off by itself. Why these are here and what is planned for them is unknown. The two unrestored ones are in pretty rough shape.

This one is has the worst interior.

Quite the contrast to the black bus, which has been converted into a private coach, and very nicely at that.

Here’s the wheel house of that one; contrast this to the driver’s compartment I showed from the other bus a ways back. This bus, like many older GM Coaches, has been converted to an automatic transmission, as shifting the original non-synchro Spicer required careful double-clutching and patience, given that the linkage was almost 40′ long. Downshifting one of these was a real skill, and not all mastered it fully, although the best drivers could shift them even without the clutch, or just “floating it” a bit.

Someone’s got their work cut out for them with the two rough ones, but maybe they’ll be back on the road again; Scenicruiser heaven instead of hell.

If so, they probably won’t end up in quite in the shape of this one, though. It’s an absolutely perfectly restored 1954 Scenicruiser for rent, via this web site greyhoundcoach.com. It’s in the original 1954 livery, and the inside is equally authentic. Let’s go for a ride.

My only ride in a Scenicruiser was highly memorable, and I’m ready to relive again. We had no occasion to ride Greyhound buses in Iowa City or Baltimore. But in the summer of 1969, we were heading back to Austria for the summer, on a charter flight from NY. So we rode a charter bus with other folks from Hopkins in the group, and our bus was a rather tired Scenicruiser, as they all were after Greyhound was done with them.

I was so stoked about the trip already, going back to Innsbruck for the first time since we left in 1960. And when it turned out that a  Scenicruiser, my favorite bus, natch, was to be the first leg of this highly memorable trip, it really got my buzzed. I was sixteen, and in my usual eager (anxious) self made sure to get in the front of the line in order to get what I knew would be my preferred seat on one of these.

Not down here, by the bathroom…

Not back here either.

Right there, the front seat on the left, where I sat with my little brother. I can still feel that tufted vinyl on the bulkhead, where I leaned forward to gaze out over the front of the bus and the road ahead. And I can still feel the jerky, shuddering starts, thanks to a worn or fouled clutch, as well as the distant howl of the engine in the back, rising in each gear, then dropping…..and a long…pause….waiting for the revs to match up to the gears, and then the next slow climb up the scale again. I could look down the stairs, and see the driver working that great big stick shift, pausing in neutral before sliding it home into the next gear.

These old buses were none too quick; today’s 500+hp turbocharged buses with their slick-shifting automatics would leave this old Scenicruiser in the dust. But it got us there, ambling along I-95 at about 65.

The Eagle turned out to be the better new big postwar 40′ bus, but the Scenicruiser became an icon, its distinctive bi-level shape instantly recognizable. It was just the only bus kids and average folks could recognize out of all the rest: Look, look; there’s a Scenicruiser! I doubt we’ll ever hear those excited words about another bus again.

Two excellent sources on Scenicruiser history: 1974 Motor Age at scenicruiser.com   bluehoundsandredhounds.info

If you’re a GM bus fan, here’s some other articles at CC: GM Coach “Old Look” Transit Bus   GMC Coach “New Look/Fishbowl” Transit Bus

And here’s a close look at the 1958 Kässbohrer Setra Continental Trailways Super Golden Eagle articulated bus.