Getting tight and busting loose

As you put all of your weight against a wrench that’s doing battle with a stubborn fastener, have you ever wondered, “Who was the Brutus that put this on so tight!?”

It’s likely the culprit was someone with equal or even less strength than you.

That’s because the torque needed to loosen a fastener can be as much as six times greater than the torque it takes to tighten it, says Dick Wright, chairman of Wright Tool.

When a new fastener is installed, it has a fine layer of lubrication. As it is torqued tight, the mating threads act like an accordion, squeezing lubrication out. Result: metal-to-metal contact that bonds and corrodes. Over time vibration can make a fastener even tighter.

Wrench selection
When it comes to removing fasteners, a box wrench or socket is almost always the best choice, says Connie Hudson, global product line manager for mechanics tools at The Stanley Works.

“When selecting a wrench, especially when it will be used to bust fasteners loose, look for a wrench with a thicker neck and a longer shank. Wrenches for these jobs need more beef to hold up to the higher torque loads,” she says.

Fastener tightness depends on the wrench/fastener interaction. “It’s best to use the largest drive you can. Use a smaller one only if there is a space or access issue,” says Wright.

Sockets are usually the first choice because they allow fast fastener removal once it’s loose.

With sockets, handle selection is important. “Don’t add cheater bars to wrenches. They are not designed to take the added pressure they produce. Socket wrench handles come in a variety of styles to suit certain jobs. The reverse ratchet is the strongest and most versatile, but a flexible handle offers more leverage than a ratchet. Use a bull bar on 3/4" or greater size drives for even greater leverage,” Wright says.

When it’s really, really tight
If the fastener simply won’t budge, douse it liberally with penetrating oil and let it soak in before putting a wrench to it. If that doesn’t work, then it’s time to bring out the heavy artillery, say the experts.

Often, an impact wrench can exert the force needed to loosen a stubborn fastener. “Use only impact sockets with impact wrenches. These sockets have thicker walls and can take the force dished out by the tool.

“If the impact wrench can’t budge the fastener, use a more powerful impact wrench. Don’t turn up the pressure on the tool because it can overload the socket and can injure the operator. Instead, use a larger gun,” Wright says.

A slugging wrench is also a good option. “A slugging wrench is built to be hit with a hammer to drive the fastener loose. Never hit a regular wrench with a hammer to drive the fastener loose,” says Wright. He also reports some users have removed a stubborn fastener by heating it with a torch or cooling it with dry ice.

Get the right fit
In the world of increasing metric sizes, it’s tempting to grab whatever wrench comes closest in size. This can lead to a sloppy fit that can damage a stubborn fastener.

“Companies are coming up with ways that make identifying wrenches easier, and “twin-drive” wrenches have special geometries that allow them to be used on SAE and metric fasteners.

“For example, Proto offers Torque Plus and Stanley offers Max Drive wrenches that have a half-moon area in the hex design.

“This allows the wrench to engage the fastener without an exact fit. It also gives you 15 percent more torque because it puts the torque against the flat sides of the fastener instead of just on the corners,” Hudson says.

Special wrenches, special uses
In the last 10 years, wrench designs have become more sophisticated, offering hybrid styles that combine the best of two wrenches into one tool. The best example is the gear or reverse-gear wrench that is a cross between a ratchet and box wrench.

“A gear wrench or reverse-gear wrench is like a ratchet and box wrench all in one. It is perfect for getting at hard-to-access fasteners. They have a through-the-wrench feature that allows them to be used on long bolts. Most have 72 gear teeth so they can work in small increments and can work even in tight areas,” Hudson says.

“A reverse-gear wrench works much like a socket drive, allowing the user to switch wrench direction without removing the tool from the fastener. These wrenches have been on the market for about 10 years and quickly gained popularity in the automotive field, but are really catching on with a variety of users,” Hudson says.

As handy as these wrenches are, it’s best not to use them to break a fastener free. Instead, use the open end of the wrench for busting the fastener loose, then switching to the gear wrench to finish the job.

Open-end wrenches are great for quick adjustments because they can turn fasteners quickly. However, tight fasteners may be damaged if the wrench slips.

“Don’t use an open-end wrench for torquing down fasteners,” says Wright. They offer only two points of contact with the fasteners vs. six points of contact with a socket or box wrench.”

New open-end designs
Open-end wrench designs are changing. Wright Tool’s WrightGrip open-end wrench has serrations inside its beefier jaw, allowing it to get a better grip on slightly worn or damaged fasteners.

“This wrench is stronger so it can take the increased torque. It has the strength to remove even a Grade 8 fastener. There is no change in size, but there is more radius in the corners and more metal in the base of the jaws. That means the wrench will not spread as easily as other open-end wrenches,” Wright says.

For best results, never cock an open-end wrench on a fastener. Fully seat it on the fastener for the most power and stability.

Adjustable wrenches have their place
“On softer fittings, an adjustable wrench can be the best wrench choice because of its ability to precisely match the fastener size.

“However, adjustable wrenches are very slow to use. In the perfect world, it would be great to have an adjustable wrench with a ratchet handle, but we aren’t quite there yet,” says Hudson.

Flare nut wrenches
This is another hybrid wrench that looks like a cross between a box and open-end wrench.

It offers more contact with the sides of the fastener like a box wrench, but allows the user to slip it onto tubing connections. “They are good for tubing connections, but not built for high torque situations,” Wright says.

Published in the July/August 2003 issue of Contractor Tools and Supplies magazine.

back to top