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Gear Test: Master Lock adjustable mount

Trailering safety is directly linked to the selection and proper use of appropriate equipment.

Trailering safety is directly linked to the selection and proper use of appropriate equipment. An often overlooked part of the safety equation is that the trailer needs to remain level with the ground when connected to the tow vehicle. Master Lock’s adjustable-height ball mount addresses this issue.

 If the trailer is lower in front, too much weight will be exerted on the rear of the tow vehicle, causing it to dip while rising in the front. This serves to unload the front tires with a resulting loss of steering control. If the trailer is higher in the front, the tow vehicle’s front tires receive additional weight while the rear tires lose traction from the weight loss.


This not only can encourage trailer sway and fishtailing issues at speed, but makes it more difficult to retain traction when launching and retrieving the boat.

To help keep things level, conventional ball mounts are available in various drops. They also can be reversed to provide increased height for the trailer tongue. I own several trailers of varying configurations, so I also own ball mounts of varying drops. Master Lock’s adjustable-height zero-tilt ball mount both simplifies the leveling process and eliminates the need to own numerous mounts.

The product fits into the tow vehicle’s 2-by-2-inch square receiver in the same manner as conventional ball mounts, but it uses an adjustable column, also 2 inches square, that allows the user to raise or lower the hitch ball, even with the trailer attached. The ball mount is adjustable from a 7-3/4-inch drop to a 6-1/8-inch rise (by inverting the mount). The process is simple and requires turning the center threaded shaft with either a 3/8 square ratchet drive or a 7/8 wrench. The adjustable column is graduated in 1/4-inch increments, allowing consistent adjustments.

Master Lock’s patent-pending One Tool Torque, or OTT, system allows installation of its specifically designed trailer ball to the ball mount using a single tool. Traditional trailer balls require some method of preventing the ball from rotating while tightening the lower nut. Master Lock has installed a 1/4-inch pin in the ball mount that, when aligned with the OTT ball, prevents the ball from spinning. I had no difficulty in applying the required 250 foot pounds of torque to the 1-1/2-inch nut without ball rotation.

Being a bit skeptical of the height adjustment process and precisely how much effort is required to make said adjustment, I hooked up a trailer that has a tongue weight far in excess of the ball mount’s 500-pound maximum rating. Using a 12-inch-long ratchet handle and 7/8 socket, it was simple to raise and lower the attached trailer tongue through the full range of available drop. The effort required was minimal — less than 20 foot pounds — and was similar to cranking a well-oiled trailer jockey wheel. I then adjusted the ball mount to the trailer height and towed more than 50 miles with no change in the mount’s height.

The component and assembly quality is good, as expected from Master Lock, but there are few things I will pay attention to over extended testing. One concern is that the height adjustment screw is exposed to the elements through a forward-facing slot in the adjustable column. Because the screw should be well-lubricated for proper operation, I assume it might pick up road sand and debris easily. A very minor point, but when adjusting the column height with a trailer attached, the rear face of the adjustable column rides against the fixed portion, potentially wearing away the surface plating and providing a way for rust to begin.

The adjustable ball mount is rated for a 5,000-pound maximum load, with a 500-pound maximum tongue weight, and requires a ball with a 1-inch-diameter shank. Master Lock says the towing items exceed American and Canadian automotive aftermarket industry standards and the Society of Automotive Engineers Towing Specifications J684 and CSA D-264.

Overall, the Master Lock adjustable-height zero-tilt ball mount and One Tool Torque system combines two good products that work nicely together to make trailering safer and easier. The ball mount retails for $65.60 from Master Lock but is available from other suppliers at slightly discounted prices. The OTT hitch ball (1-inch shank) is sold separately and retails for around $8. For more information, visit