THE Class 86/4 sub-class first made its appearance in the mid-1980s when Class 86/0s were gradually fitted with SAB resilient wheels and Flexicoil springs to bring them in line with Class 86/2s used on express passenger services on the West Coast Main Line.
The modifications were first made to Class 86s dedicated to passenger traffic in the 1970s to improve the ride and reduce the impact of unsprung weight of axle mounted traction motors on the track when running at high speed. Unmodified Class 86s were restricted to freight and secondary duties where their maximum permitted speed of 80mph would not be a liability.
The first modifications made to
