Mack Recalls 341 TerraPro Trucks Over Steering Gearbox Bolts

Campaign 26V509000 covers 341 TerraPro trucks whose steering gearbox fasteners may loosen, and owner letters are not due until October 5. A loose gear mounting bolt is already its own federal violation, so the check does not have to wait for the mail.

Mack Recalls 341 TerraPro Trucks Over Steering Gearbox Bolts

Mack is recalling 341 TerraPro trucks because the fasteners that hold the steering gearbox to the frame can loosen. The letters telling owners about it are not expected to go out until October 5. That two-month gap is the part worth talking about, because the exact condition being recalled is something a roadside inspector can already write up today, with or without a campaign number.

What the campaign actually covers

The campaign is 26V509000, filed by Mack Trucks, Inc. and received by federal safety regulators on August 6, 2026. It covers certain 2025 model year TerraPro trucks, and the potential population is 341 units. The component is classified as steering critical fasteners.

The defect is described plainly: the steering gearbox fasteners may loosen. The consequence is described just as plainly: a loose steering gearbox can result in a loss of steering.

The fix costs the owner nothing. Dealers will inspect the fasteners and tighten or replace them as necessary, free of charge. Mack's internal number for the recall is SC0497, and its customer service line is 1-800-866-1177. There is no park-it warning attached to this campaign, no park-outside warning, and no over-the-air update — it is a wrench job.

Why October is the wrong date to plan around

Owner letters are expected on October 5. Nothing stops a shop from checking the truck before then, and there is a good reason not to wait: 49 CFR 393.209(d) already says that "the steering gear box shall not have loose or missing mounting bolts or cracks in the gear box or mounting brackets."

Read that again next to the defect description. The recall and the rule are describing the same physical condition. A driver who gets pulled into a scale with a gearbox bolt backed off is not protected by the fact that the letter has not arrived yet — the fastener condition stands on its own as a violation.

And 49 CFR 396.7 sits behind it: a vehicle must not be operated in a condition likely to cause an accident or a breakdown. If the condition turns up on the road, that section allows the truck to move only to the nearest place where the repair can safely be made, which is where the order of the first decisions matters, and only when moving it is less hazardous than leaving it there.

The one number you can measure in your own yard

Most of a steering inspection needs the truck in the air. Steering wheel lash does not. 393.209(b) sets a hard ceiling on how far the wheel can turn before the front wheels start to move, and it changes with the diameter of your wheel. For power steering:

  • 16 inches or less — 4 1/4 inches (108 mm)
  • 18 inches — 4 3/4 inches (121 mm)
  • 19 inches — 5 inches (127 mm)
  • 20 inches — 5 1/4 inches (133 mm)
  • 21 inches — 5 1/2 inches (140 mm)
  • 22 inches — 5 3/4 inches (146 mm)

A manual system is held to far less on the same wheel: 2 inches at 16 inches of diameter, and 2 3/4 inches at 22. If your wheel diameter is not on that list, the limit becomes an angle instead — 14 degrees of rotation for a manual system and 30 degrees for a power system.

Measuring it takes two people and five minutes. Engine running, wheels pointed straight, one person turns the wheel slowly until the front tire just begins to move, and marks the travel at the rim. Compare the mark against the number for your diameter. Excess lash is not proof that a gearbox bolt is loose — worn joints and a loose column do the same thing — but it tells you the steering has slop worth chasing before it becomes someone else's finding.

What the rest of the section asks for

While the gearbox is being looked at, 393.209 covers the neighborhood around it, and these are all pass-or-fail items rather than judgment calls:

  • The steering wheel is secured and has no spokes cracked through or missing.
  • The steering column is securely fastened.
  • Universal joints and ball-and-socket joints are not worn or faulty, and have not been repaired by welding.
  • The pitman arm on the gear output shaft is not loose.
  • The wheel turns freely through the limit of travel in both directions.
  • On power systems, no component is loose or broken, belts are not frayed, cracked or slipping, nothing leaks, and the reservoir has enough fluid.

What to do this week

If you run a 2025 TerraPro, look your VIN up now rather than waiting on the mail, and book the inspection under SC0497. If you run something else, the useful takeaway is the one that costs nothing: check your lash, put a wrench on the gear mounting bolts at the next service, and write what you find on the driver report instead of carrying it in your head.

When the check turns into a repair and you are away from your home shop, the Truck Saver Finder lists shops by location and specialty, and listing a shop there is free. More operator-side maintenance and compliance coverage is at thetrucksavers.com.

Original source

National Highway Traffic Safety Administration — recall campaign 26V509000, report received August 6, 2026, with 49 CFR 393.209 and 396.7 as published in the Electronic Code of Federal Regulations, text in force August 2026.