FORGOTTEN MOTOCROSS TECH: THE LUFT HYDRAULIC CHAIN TENSIONER
Motocross history is filled with examples of creative ideas that were heralded as groundbreaking, but, because of the rapid rate of change in development, sank into the swamp of forgotten technology. Although some are best left abandoned, others were truly innovative (if not ultimately successful). MXA loves to reveal motocross’ tech trivia. Do you remember this idea? The Luft Chain Tensioner.
The inherent problem of the long-travel movement (that started in 1974 and lasted into the mid-’80s) was how to handle chain slack. Since the countershaft sprocket on old engines was located several inches in front of the swingarm pivot, when the swingarm moved through its arc, the chain would go from very tight to very loose. This created a booming business in spring-loaded chain tensioners (with a roller on the end). When the chain went slack, the tensioner would tighten the chain to keep it from derailing.
Chuck Parks, with the help of National star Kenny Zahrt, started Luft Racing. Luft’s best-selling products were remote shock reservoirs, but its most unique product was an air-pressurized, hydraulic chain tensioner. Air pressure pushed a leverage arm against the chain, and hydraulic pressure kept it in contact. Of course, the Luft chain tensioner was overkill. The eventual solution was to redesign the engine so that the countershaft sprocket would almost brush the swingarm pivot (lessening chain slack).