How Tight Should the Fasteners on a Boat Trailer Be? The Answer May Shock You.

casey0847
Aug 27
2 min read

Most boat trailers are either welded together at the joints or they are bolted together with fasteners, like U-bolts and nuts. For those that are put together with fasteners, it's crucial to know how tight they need to be. If fasteners are too loose, then you run the risk of coming apart. If they are too tight, they run the risk of cross threading and breaking.

So what are the standard for most boat trailers? We asked our head engineer, Tyler Kane, from Venture Trailers.

Tyler's Recommendations

According to Tyler, the torque specs (for Venture Trailers) should be as follows:

45-65 ft/lbs for U-bolts that are steel on steel, like clamping springs and axles together.

50 ft/lbs for U-bolts going around an I-beam or steel tubing.

SNUG (no torque spec but hand tight) for any spring bolts connecting springs to equalizers

70-80 ft/lbs for structural bolts like use to mount crossmembers to the frames.

Stainless Steel

Stainless steel has a tendency to gall, or cold weld, to another stainless steel part when it is tightened too tight. It's crucial to use a torque wrench when tightening these parts as the only choice to get galled up stainless steel off is to break it or cut it off.

Lug Nuts

Lug nuts vary based on if the wheel is made out of steel or aluminum and how large the wheel is. For most of our trailers, the spec is set at 110 ft/lbs.

With boat trailers, it is important to properly seat the lug nuts at 10 miles, another 15 miles, then another 25 miles. Do this when you first buy a trailer and also when you need to remove a wheel for service.

If you fail to properly re-torque the lug nuts, a spoke can shear off or worse, the wheel can come off completely.

Lock Nuts vs Lock Washers

Lock nuts, the ones with the nylon insert, are preferable to using lock washers but are more expensive. Also, lock washers tend to need periodic tightening more often.

Tightening Intervals

It's important to retighten the bolts and lug nuts to the torque specifications periodically as the weight they carry along with the amount of vibration can cause the fasteners to come loose.

Using a Torque Wrench

Torque wrenches should be calibrated and when stored, should be stored at the lowest setting. Typically, when the preferred torque is reached, you will hear a click. Remember that "hand-tight" is only 10-20 ft/lbs and impact wrenches can easily make your fasteners too tight, leading to galling or cross threading.