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BACKGROUND
Page 39
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Richard Fisher first tried to eliminate recurring tyre shoulder wear by reducing front axle camber in the 1990s, but he also knew that many of the problem vehicles were seriously 'pulling left' too.
Around that time, Josam was altering axles using heat treatment and although there was some improvement it didn't really eliminate wear.
By the end of 2001, when the likes of Mercedes-Benz, Scania and Volvo began introducing negative camber into their axle specification, Fisher continued his preliminary testing of suspensions, drive-axle alignment and tyres pressures.
But, as he focused on castor angles, he found that trucks with more offside castor were the worst affected but it was less of a problem the other way around.
Fisher also discovered a tremendous variance between manufacturers, with regard to axle alignment specifications and lateral tolerances.
A vehicle spec-sheet might say 2.5° +/0.5°, but he believed it was the difference between the two sides that really mattered.
"Most truck axles are generally within limits, but when each side is at opposite extremes you get adverse performances and early tyre shoulder wear," he says.
Knowing that Josam and Beeline had been routinely realigning axles cold in the US and Australia for many years, Fisher followed their basic method using Josam J01000 equipment to make castor alterations. As the castor angles were altered, tyre wear and handling improved.
"To date, we've altered the axles of around a dozen vehicles and the feedback is very promising," he concludes. Contact: RR Garages on 01469 571666; Josam UK on 01788 551478.