Sisu M-Series History

Introduced in 1970 alongside the conventional-cab R-series, the M-series was Sisu's forward-control offering of the decade, providing better cab-over-engine access and payload flexibility. Four chassis layouts were offered — 4×2, 6×2, 6×4, and the unusual 8×2 — reflecting the diverse demands of Finnish forestry, construction, and long-haul haulage.

The M-series adopted the Vanaja lifting tandem axle system, a mechanism that allowed rearmost axles to be raised when running unladen to reduce tyre wear and fuel consumption — particularly valuable on Finland's long, sparsely populated roads. The last M-series units were produced in 1984, at which point the modular S-series (introduced 1980) had taken over as the primary product line.