This article was originally published in the 2001 issue of Cycle World’s Power & Performance magazine.
When Harley first announced its VR1000 Superbike program, the speculation was rife: Would The Motor Company ever produce a streetbike powered by this high-tech race engine? Well, with the V-Rod, that question has been answered: It all depends upon your definition. The literal answer to that question is “no,” while the practical answer is “yes.” Despite sharing not a single component with the VR1000, the Revolution engine in the V-Rod can reasonably be considered a street-going version of the Superbike motor. That’s because, in the words of Harley-Davidson Powertrain Engineer Joe Schaffer, “We kept the VR’s architecture.” Both the Revolution and the VR share some basic features that haven’t previously been seen on Harley engines. Start with the 60-degree vee-angle, which is 15 degrees wider than that of H-D’s air-cooled engines. The wider vee makes for a longer engine from the leading edge of the front head to the trailing edge of the back one; it also reduces vibration and makes room for more piston-skirt-to-piston-skirt clearance at the bottom of the stroke, necessary in a short-stroke, short-rod design.
The similarity between V-Rod and VR1000 engines continues with their offset cylinders and connecting rods. This offset readily allows both engines to use one-piece crankshafts, with auto-motive-style connecting rods running on plain bearings, rather than Harley’s typical rollers. Both engines use double overhead camshafts (four in total) to directly actuate four valves in each cylinder head, for improved breathing and combustion at very high engine speeds. Both also use an intermediate shaft at the base of the cylinders to drive the cam chains, a technique that allows smaller sprockets at the cams and more compact cylinder heads. And, there’s that most visible similarity between the two engines, liquid cooling.
Jeff Coughlin, Harley’s project leader for the V-Rod, notes even more similarities between the two. The balance shaft from the VR has stayed, and in relatively the same position.” That places the balancer low, behind the crank; its single counterweight can’t compensate for all vibration, but can counteract part of it. For the racebike, that’s enough; on the streetbike, rubber engine mounting further diminishes the vibes reaching the rider. The clutch is in the same position, as well. Drive to the clutch on both VR and V-Rod engines is not by Harley’s typical triple-row primary chain, but by gears. The racer uses simple spur gears, while the streetbike uses a split, spring-loaded gear pair at the clutch to reduce backlash and noise.
In many ways, it was the quest for reduction of mechanical noise that drove the Revolution into being an all-new engine, one that shares architecture but not components with the VR. Noise laws worldwide, and especially in Europe, have been getting tighter. If Harley intended to build an engine for the new century, it would have to be one that could meet all of that century’s current and proposed standards. Another motivation for change was time: “We were pretty busy with the Twin Cam engine when this project started,” says Coughlin. The solution Harley found for its shortage of engineering personnel was to enlist the aid of an old ally in the design of the Revolution: Porsche Engineering. The consulting division of Porsche had worked closely with Harley before, including designing the never-produced V-Four Nova in the last days of AMF ownership. Now Harley turned to Porsche again, enlisting the Germans, aided by a small team of Milwaukee engineers, to help transform the VR concept into a new engine. The emphasis would be on strength, produceability and quiet, rather than on the performance-at-any-cost goals of the VR.
It’s not hard to find Porsche’s influence inside the Revolution. The VR’s screw-type cam-chain adjusters have been replaced by hydraulic tensioners acting against chain guides that look as if they could have come from a 911 or Boxster motor. The five-speed gearbox is from German supplier Gertag (manufacturer of BMW motorcycle gearsets) and makes use of very automotive-like helical gearsets for second, third and fourth gears—the very gears, not coincidentally, used in European noise tests. According to a Gertag engineer, the use of helical gears instead of traditional motorcycle straight-cut spur gears in those locations resulted in a 2-decibel decrease in sound level during a ride-by sound check. The payback is that getting rid of unwanted engine mechanical noise permitted a slightly louder exhaust note while still passing the stringent noise standards.
As in most Porsche engines, the Revolution’s connecting rods are forged in one piece with end caps cracked away after the big end is machined for perfect alignment. So, in many ways, the Revolution is a VR seen through the filter of Porsche’s own best practices. Porsche is even taking a substantial role in the manufacture of the engine, working with Harley through a joint venture in the Kansas City plant that currently builds Sportsters, and now sources the Revolution.
But if the V-Rod’s engine is a joint project, the rest of the machine is all Milwaukee Harley-Davidson, the manifestation of a vision held by Willie G. Davidson and his colleagues in H-D’s styling department. They began playing with a VR1000 racing engine years ago, trying out such things as building a VR-powered Softail—or “learning what not to do,” in Willie G’s words. The proportions of a modern racing engine like the VR are completely different from those of the classic Harley powerplants. The shrink-wrapped cases and small primary drives and gearboxes of modern engines have none of the visual mass of a Big Twin, and one simply can’t take the place of the other. So Willie G. & Co. began looking for a different type of vehicle to house the engine.
The idea of a drag-racing influenced machine was a natural. It aligned with the high-performance goals of the new engine, and it fit with Willie’s vision. Motorcycle drag bikes have long swing-arms that minimize wheelies; a long swingarm would look good coupled to the Revolution’s short gearbox. Drag bikes are long and low, and Willie liked that look. He also wanted the raked-out front ends that drag machines traditionally have—something like a very kicked-out, 38-degree fork angle.
But with that part of the vision, he initially ran into resistance from the engineering department. “They told us it wouldn’t work,” he says. “But styling told engineering, ‘You can’t say no until you’ve actually tried it.— Soon afterward, a Sportster test bike was given a 34-degree steering-head angle, with the fork legs kicked out farther via triple-clamps machined with 4 degrees more angle relative to the steering head. That’s not a new trick; for 20 years, Harley has been using different-angle triple-trees on FLs, and numerous other manufacturers have employed the same tactic from time to time. That test Sportster handled very well, so the V-Rod was finally granted its signature raked-out look.
On other parts of the machine, the stylists gave ground from the beginning. On Big Twins, they had for decades insisted on tiny, traditional mufflers; but the shorty duals of a Big Twin have less than a liter of volume apiece, and simply can’t be quiet and non-restrictive at the same time. For the V-Rod, excellent performance in stock form would be vital, and its muffler and airbox would need to be huge to achieve that goal; each would require more than 10 liters of volume. Says H-D Styling Director Louie Netz, “We knew we could solve the exhaust system and make it a part of the look, but the air cleaner—well, we knew we weren’t going to hang it from the side. We’d already seen that on Buells.” That left only one place for the airbox to go: above the engine in the normal gas tank location. The gas tank would have to go under the seat, which, in turn, dictated twin shocks; there was no room for gasoline and a single shock in front of the back tire.
The styling team also had a clear picture of what they wanted the V-Rod’s frame to look like: They wanted it to literally frame the engine, like a picture frame, and “to hang the engine in space,” says Willie G. Unlike most other Harleys—other than the FXRs—the V-Rod frame would be prominent on the outside of the bike, so it was vital it should look good. From the engineering point of view, it was equally vital that it be stiff for good handling.
With these needs, styling and engineering began an iterative collaboration that ended with the design of the V-Rod frame you see today. Big tubes were good, because they give adequate strength with ungussetted joints—a clean look that scored high with styling. The big tubes also scored high with engineering for stiffness, since bending resistance increases exponentially with diameter. So, 1.5-inch tubes were the choice.
Manufacturing processes for the frame were stressed to the limit for strength and appearance. All the joints are robotically welded to produce crisp, well-finished welds. The top frame tubes swoop in complex curves that couldn’t have been made at all a few years ago; now they’re produced by hydroforming the tubes in hard dies that are capable of producing the three-dimensional shapes agreed upon by stylists and engineers.
Similarly, engineers and stylists alike sweated the details on the radiator and oil coolers. There was no way that Willie G. was going to let the V-Rod ship with some black-painted, boxy radiator on it, like on some of the Japanese cruiser models. “It had to be an integral part of the design,” he says. “Black paint doesn’t make the radiator invisible.” The solution emerged when the engineers and stylists were working together doing wind-tunnel testing. It became clear that the space immediately behind the front tire was dead to airflow, so they concluded that they might as well block the front of the radiator there. The next logical step was to make side scoops that would catch clean air and direct it into the radiator. Once those scoops were made of the same signature aluminum that covers the rest of the bike, Willie had the shape of his styling-integrated cooling system.
That unique bodywork—anodized aluminum protected by only a thin coat of clear acrylic—was, in and of itself, the cause of another internal battle at Harley-Davidson. Willie G. wanted the fenders, airbox cover and radiator shrouds all to be made in this way, and no one doubted that the look it provided was cool. The engineers had no problems with the use of this strong, light material for that purpose, but manufacturing questioned whether or not it could be produced at a reasonable price. And for good reason: Anyone who has spent time around a factory would question how such parts could possibly make it through the manufacturing and assembly process without getting scratched, and how closely the color match could be held from one batch to another. Harley’s manufacturing people experimented with this process but hesitated to commit to it; after all, they would have to build it. Meanwhile, Willie G. bombarded the manager of the Kansas City plant with e-mails, each containing a single word: “ALUMINUM.”
Whether brought about by this barrage or by the successful completion of the experiments, manufacturing finally conceded: The V-Rod would gleam in aluminum just like a 1930s’ DC-3, and look just as ready to take wing.
Of course, perhaps the best way to think of the V-Rod is as a machine designed by serious motorcycle freaks working for a very successful company that gave them almost everything they wanted, from a modern, 1130cc engine to a sculptural frame to a unique head-light that cost more than half a million dollars to tool (“and looks like it’s going fast when it’s stopped,” according to Willie G.). It’s a machine that simply oozes back the passion of the people who built it.
Such motorcycles are all too rare in this era of committee-designed every-thing. That’s why the V-Rod is special indeed, even if not a single one of its metric fasteners is shared with the racing VR.
Source : Hotbikeweb
