U-bolts get their name from their shape. Quite simply, it is a rod that is threaded on both ends, and bent into a “U” shape. These bolts vary in size and shape. You will find U-bolts with a smooth curve, designed to fit around a cylinder such as an axle or exhaust tubing. You will also find U-bolts that have a more squared off shape designed to hold flat surfaces such as square tubing, wooden blocks, or any number of flat layers together. Often times there is a bar or cross-member drilled with holes spaced and sized so that it will slide over the open ends of the U-bolt to enclose it. Nuts are then screwed onto the threaded ends of the U-bolt to be tightened to hold whatever is enclosed in the U-bolt.
Galvanized U Bolts
In order to preserve the metal, and prevent rust, bolts designed to be used outdoors are often galvanized. This is a process in which a protective outer metallic coating is added, most commonly achieved by dipping. Another method of galvanization can be completed through electrochemical or electrodepositing processes. Most galvanized U-bolts are created using the hot dipping method. Galvanized U-bolts are commonly used in construction of buildings, decks, and even in vehicles. Anywhere you find a U-bolt being used in a setting where it will remain outdoors. The galvanization process will protect the U-bolts from rusting for many years, helping them to last so that whatever was built with them will, too, last.
Leaf Spring U Bolts
U-bolts are employed to hold the leaf springs to the axle in vehicles. The leaf spring is flat, while the axle is a round tube. Leaf spring U-bolt dimensions are specific for the vehicle they are being applied to. The U-bolt sizes vary to fit tightly around the outside of the axle tube, while a flat cross-member is used to pinch the axle tube to the leaf spring. These bolts are made with hardened, often galvanized U-bolts designed to handle the large amounts of force applied to them as the vehicle is driven on uneven surfaces. Truck U-bolts are much thicker and harder than the ones used as trailer U-bolts, boat trailer U-bolts, or car axle U-bolts.
Stainless Steel U Bolts
304 stainless steel is used to make stainless steel U-bolts and the stainless steel nuts that usually go with them. These bolts are designed for use when the U-bolts will be seen. They are much more decorative and appealing to the eyes. They may be used as handles, or in artistic creations. The U-bolt size can vary from less than an inch to over 6”. The U-bolts dimensions can vary in the diameter or gauge of rod used, curve (can be round or squared), width (distance between the tips), and length (distance from the curve to the tips). You will sometimes see them used in holding pipes and lines in situations where they will be visible.
Custom U Bolts
There are very few companies that will make custom U-bolts, as there are literally thousands of U-bolt dimensions available on the market. One company who will create these can be found online at www.dsuban.com. When ordering custom U-bolts, most companies will not allow you to return them, so you will want to be sure you get the dimensions correct. The company will need to know if you are looking for a curved, “v” shaped, or squared U-bolt. The U-bolt size will also need to include the distance between the arms, as well as the sized rod, and how much you would like threaded. You will also need to include length of the U-bolt, which is measured from the outside of the curve to the tips of the threaded rods.
The most popular u-bolt sold on Amazon.com is the National #N222-364. It measures 5/16” x 2” x 5” and is squared off. At $.72 it is an inexpensive item, sold with no nuts or additional parts. As is often found with this type of item, there are no reviews left on Amazon.com for this item.
The next most popular U-bolt is made by Global Industrial. It is model T-304, a 4” stainless steel U-bolt. It includes 4 hex nuts, and designed to be used with heavy loads. It measures 8” long by 8” wide and 4” high. Again, no one has reviewed this item on Amazon.com.
The third U-Bolt is the Battalion 1WVE6. It is a squared U-bolt that measures 6” x 6” x 4”. This bolt sells for $5.44. It is squared off, made with steel buy coated with zinc. This one includes nuts and a plate. The one person who reviewed it used it as a handle outdoors, and gave it a 5 out of 5 rating.
U-bolts are created from various materials including stainless steel and hardened steel alloys. Some U-bolts are designed for outdoors, as the galvanized U-bolts are, and some are designed for decorative use such as the stainless steel ones. U-bolt sizes and U-bolt dimensions can vary so greatly that there are literally thousands of them available on the market. U-bolts are used in construction, automobiles, and even such simple daily items such as lamps and fans. They are all around us every day, although we don’t always recognize them. Many cabinet and drawer handles are decorative U-bolts. There are hundreds of companies that manufacture U-bolts for different applications and uses. If you cannot find the U-bolt dimensions or sizes you need for your application, you may order custom U-bolts from a variety of companies. Some local hardware stores may even have the ability to bend and thread rod to create the U-bolt that you need, although you may want to order them from a larger, manufacturing company if you are in need of U-bolts that are going to be used under a large amount of torque or stress. The process of rolling threads creates a much stronger thread than cutting threads. The equipment to do this is not likely to be found in a hardware store. They would most likely cut the threads. Just be sure the U-bolt you use is strong enough to do the job it is intended for. The leaf spring U-bolts on your vehicle can mean the difference between the axle staying in place, or coming off.