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| Map of Travels |
| The Amol Precision OL Special Oscar Liebmann’s DOHC Flat Twin leaps from the nest to the glare of Competition A small crowd ringed the trailer, staring at an immaculate short-stroke racer, speculating on its chances of winning or even surviving AAMRR’s competitive 500cc and open class events. The O.L. Special was lifted and gently pushed and pulled into place. Tie-downs were wrestled into position and securely tightened, checked, prodded then checked again to be sure. Cheerful banter filled the warm air as Oscar Liebmann of Amol Precision in Dumont, New Jersey, walked toward the crowd. Many thoughts filled his mind. Responsible for the birth of this modified and refined BMW DOHC racer, Liebmann considered the untold hours that became years, the money, the decisions and myriad small problems that together shaped and gave substance to the object on the trailer. This was to be the O.L. Special’s first test in competition, the August Gold Cup races in Canada. With the 1967 racing season half finished, Liebmann was eager for combat. There were still tuning problems to overcome, but what better place than on the track in the thick of things. Soon all was ready. The car and trailer moved onto the road and the long journey to Harewood had begun. Rain pelted the racers as they ran the course. Riding was rugged, making adjustments in the pits difficult and uncomfortable. Kurt Liebmann, Oscar’s youngest son and respected rider on the AAMRR circuit, rode to second place in the 500 expert event. For a machine on its first outing, this was a prodigious feat. “The weather was awful,” Kurt said afterward. The throttle is very sensitive– difficult on dry surfaces and almost impossible on water. I don’t think I’ve concentrated so hard.” He said the engine had shown a disturbing throttle hesitation throughout its rpm range. After father and son considered several causes, they concluded that the heavy rain was responsible. They decided that they would not make any changes to the carburetor for the next race. Race weekend at Nelson Ledges delivered a welcome change of clear dry air. Kurt was rather chagrined to learn that the Special still exhibited the same hesitation he experienced at Harewood. Water wasn’t the problem, and to compound his dilemma the engine would not exceed 9000 rpm. With a design limit of 11,000 the full potential was, for the moment, at least out of reach. In spite of this handicap he was able to finish second again in the 500 expert class and took third overall. The taste of near victory was sweet, but what the gods giveth they can soon taketh away. On return from Nelson Ledges, Oscar, Kurt and their mechanic Julius Vicze reviewed their difficulties to no avail. The senior Liebmann decided to cut through guess-and-by-golly solutions by calling the BMW factory in Germany. Unable to speak with Ludwig Apfelbeck, the factory engineer responsible for the original design, Liebmann discussed his problems with engineer Max Klankermeier. He was assured by the old sidecar ace that advancing ignition and leaning the mixture even further would cure their troubles. Subsequent trials proved Klankermeier quite accurate in his diagnosis, but there were other problems that needed immediate attention. Oscar was also convinced at the time that high frequency engine vibrations upset float bowl operation causing fuel starvation. His arrangement of securing the float bowls and coils to a sheet metal ring bolted to the engine case was discarded in favor of the BMW racing department dodge of using flexible but rather stiff tubing in place of rubber hose from tank to float bowls. After the changes the Liebmanns sought a test course for further sorting out. Adequate facilities for high speed testing are almost non-existent in the New York metro area. With the exception of Lime Rock sports car circuit in Connecticut, available only one day a week, there are only back roads that are of little use. Kurt eventually got permission to run the Special at a small private airport. “With a windsock for company and a few infrequent landings,” he grinned, “we were able to make a number of banzi charges down the strip.” It soon became apparent that the real problem was ignition and had been from the beginning. The coils and condensers were changed in an effort to smooth out the upper end, but results were far from satisfactory. Back in Dumont, New Jersey, Kurt explained the problems encountered to all concerned. Richard Liebmann, Kurt’s older brother, decided to replace the points. Convinced the engines high speed breakup was caused by point flutter, he removed the English unit they were using and substituted Honda’s 305 assembly. Another trip to the airport confirmed Richard’s theory. The machine accelerated beautifully to the upper end of the scale. The Liebmanns were now of one mind, that fine tuning was the only limiting factor in developing the engines considerable potential. The Special’s third race in the Canadian Grand Prix at Mosport, Canada was the first outing for the Liebmann’s R.S. Long Stroke machine. Almost identical in outward appearance to the Special, the Long Stroke had considerably less performance, but ably ridden by Fred Simone, manager of Amol’s motorcycle sales department, the slower bike proved to be more reliable throughout the season. Meanwhile, the seemingly endless task of jetting was sorted out to the satisfaction of father and son. All concerned were confident the Special would lead the privateers to the finish line. Race day brought cold air laced with rain, certainly not weather that provides happy holiday feelings for spectators or a full measure of confidence for racers. When the green flag fell, Kurt, in the third row behind the factory hardware, started the Special immediately. Accelerating, he became wedged between two closing machines, Describing the incident later, he said, “suddenly I was off the seat, the bike falling to the right and me to the left. Somehow I was able to yank the bike upright, climb back on and screw the throttle wide open.” With one of the poorest starts of his racing career, he crossed the start line in 27th place and in 11 laps passed 22 riders. Visions of dicing with Rockett, Georgeades and Lloyd for a place behind Hailwood and Agostini made him more determined than ever. But the gods looked away. In the 12th lap the left cylinder stopped firing. Thinking the worst, Kurt pulled in the clutch and coasted into the pits. Thinking about the problem on the long ride home, Kurt stopped the car at the side of the road and looked at the points. The left side terminal lug had broken. During practice the terminal fitting on the right side of the point assembly had snapped from vibration and had been replaced. “Who would have thought it would happen again,” he muttered, “and so soon.” The AAMRR East Coast championship race at Danville, Virginia, a few weeks later was the last official race of the season. The Mosport trouble was hopefully repaired and practice was used to lean the still rich mixture. The Special was running extremely well on Saturday and later that evening Kurt remarked to friends that the bike was the finest handling 500cc machine he’d ever ridden. The engine’s higher compression and lighter flywheel allowed the bike to decelerate properly, a characteristic sadly lacking in the earlier R.S. designs. Fontana double leading shoe front brakes made quick work of pulling speeds down for the track’s many corners. “The Special was negotiating the turns faster than any 500 on the track,” Kurt stated in an interview. “Once we reach the common denominator for jetting at the various tracks, we’ll be the machine to beat,” he added with a grin. Sunday’s performance was in the money, so everyone thought. With a first place in the open class heat score books, Kurt was leading by 30 seconds in the final after Berliner’s Norton Special retired. Soon after the Special began to misfire and two laps from a sure win, Kurt pushed the 300 pound roadster back to the pits. The taste of failure was bitter indeed, especially when the Liebmanns pinpointed the cause to a duplicate of the Mosport problem—the terminal lug had split. The last opportunity for victory in the 1967 racing season was in November. AAMRR was able to rent the Upper Marlboro course in Maryland as a private club event. The Liebmann entourage was there to end the year on a positive note. The O. L. Special and its sister bike sat side by side under the constant eyes of fascinated pit personalities. Saturday and Sunday’s practice proved again that the performance was outstanding if not plagued by absurd troubles. Shortly before the 500 event Julius Vicze started his charge for the pre- race warm-up. Running for a few moments the engine shuddered to a stop. A quick glance at the point assembly revealed no breaks in the wires. In moments the problem became most serious. Vicze then checked the valve clearance and ruefully discovered that the left cylinder had none whatsoever. Removing cam box and rockers Julius found that the tower shaft bevel gear assembly has disengaged from the driving gear. A small circlip positioned to hold the two gears in mesh had fractured. A penny item dashed their hopes and defeated them again. The faces were long and somber that afternoon. After a hurried conference Oscar agreed that his R.S. Long Stroke would have a better chance on Marlboro’s twisty short course if they mounted the Specials lower ratio rear end. The switch was worth the effort. Fred Simone brought honor back to the Liebmann camp, winning a first in class and a third overall in the open event. With the long winter months behind, and memories sweetened with the patient long nights of tear down, adjustment and reassembly, Oscar Liebmann looks back with a bit more perspective. “We pushed hard,” he said, “I sometimes think we should have waited until this year to put the Special on the track. But pushing is always the difference between running well and not running at all.” The Specials two near wins helped considerably to strengthen his philosophy and reaffirm the tenet that only good design and careful assembly can bring success. |
| FOLLOW THE YELLOW LINE Motorcycle Touring with Stuart Davis and His Side Car www.followtheyellowline.com |
| Ramblings, etc. |