Vehicle recall 78V028000 · February 9, 1978

1973-1977 Mack HMM6856S

The steering pitman arm is subject to failure at the area of the transition to the arm offset due to high stress concentrations.

Source: NHTSA data as of September 22, 2026. Last refreshed Sep 23, 2026, 2:43 AM UTC.

Summary: The steering pitman arm is subject to failure at the area of the transition to the arm offset due to high stress concentrations.
Remedy: Dealer will replace the steering pitman arm, steering gear output shaft and steering gear mounting bracket.
Notes: Vehicle description: trucks.system: steering; steering pitman arm.consequences of defect: pitman arm failure could cause loss of vehicle controlwithout prior warning and a potential vehicle accident.

Recall details

NHTSA campaign: 78V028000
Reported to NHTSA: February 9, 1978
Filed by: MACK TRUCKS, INCORPORATED
Owner notification: August 14, 1978
Vehicles potentially affected: 100
Initiated by: the manufacturer
Components: Steering › Linkages

Recall 78V028000 on nhtsa.gov, with the manufacturer’s documents

Vehicles covered

As listed by NHTSA. A recall usually covers only some vehicles of each model and year, often a production date range.

Mack HMM6856S (1973-1977): 1977, 1976, 1975, 1974, 1973

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