A distribution warehouse reported that a Toyota 8FBEU15 reach truck was difficult to steer straight. The operator had to constantly fight the steering wheel to keep the truck tracking true, and the steering wheel felt "heavy" in one direction but "loose" in the other.
The technician first jacked up the rear drive axle. He spun the tires by hand; the left tire had a slight wobble. He removed the wheel and found that the rim was bent inward, likely from hitting a dock plate. However, replacing the rim did not fix the steering pull. He then checked the "dual tire pressure." The Toyota 8FBEU15 uses dual drive tires. He found the inner tire on the left side was inflated to 120 PSI, while the outer tire was at 80 PSI (spec is 110 PSI). This pressure differential created a "radius difference" in the effective drive wheel. The larger diameter (over-inflated inner tire) tried to turn the truck faster than the outer tire, causing a constant pull to the right.
The "heavy vs. loose" steering feel was traced to the rear axle pivot bearing. Reach trucks use a pivoting rear axle to maintain stability on uneven floors. The technician disconnected the steering cylinder and tried to pivot the axle manually. It was seized solid. The pivot pin had corroded due to wash-down water entering the bushing. The steering cylinder had to push against the resistance of the seized pivot, causing the heavy feel in one direction. The repair involved pressing out the seized pivot pin, replacing it with a greasable marine-grade stainless steel pin, and resetting all four drive tires to the exact specified pressure. The truck tracked straight, and the steering effort became equal in both directions.
