The Importance of Calibrating Your Torque Wrench
Before we dive into what is one of the most often overlooked tools in the average man’s garage, ask yourself the following questions: Where is my torque wrench stored right now? When was the last time I used it? What is the current torque setting at on it? How accurate do I believe my torque wrench is? Every garage, engine builder, or race team has a torque wrench, and we all use it a considerable bit! But when was the last time you gave more than a moments glance at your torque wrench? Without a doubt one of the most often overlooked and most used pieces of equipment in any race teams or home garage has to be their torque wrench. A torque wrench is a relatively inexpensive piece of equipment when you consider how often we use it to create serious horsepower or to ensure our wheels don’t come flying off when we put the car on the ground. A typical “click-style” torque wrench will usually run between $100-$400 and if cared for properly can last quite sometime. Ensuring Your Torque Wrench Isn’t lying to you What happens though when your trusty torque wrench has seen a few years, and you are starting to doubt the results it’s giving you. “We’ve seen a torque wrench be as far as 16 ft-lbs out of calibration,” explained Chris Raschke of Automotive Racing Products.ARP understands how crucial it is to have a torque wrench that is calibrated correctly. ARP works closely with many of the top NASCAR and NHRA teams as well as numerous engine builders across the country to supply engine and driveline fasteners. ARP has spent 2012 traveling across the country to every NHRA event offering a special service to the teams and mechanics in attendance. ARP brings a torque indicator that allows teams to test their torque wrench settings. Teams can walk over to the ARP tent and quickly see just how accurate their favorite torque wrench is simply by giving it a couple of pulls. “We test the torque wrench at 50 ft-lbs and 100 ft-lbs to give teams a proper reading,” continued Raschke. “We encourage and stress that everyone to bring their torque wrench to our tent and see just how accurate the wrench really is.” Why It’s So Crucial To Check Its Calibration ARP explained to us that they have seen torque wrenches as far as 16 ft-lbs out of calibration. It’s easy to think how dangerous it would be if it a wrench was -16ft lbs, but the important thing to remember is +16ft lbs would be just as dangerous, especially for engine builders. For example, let’s say you are working on a Chevy Small Block and are installing the cylinder head bolts for a 18 degree standard port cylinder head. ARP recommends torquing their hex bolt kit to 70 ft-lbs in three increments of torquing. This means at three different steps you are going to torque each individual head bolt first at 20 ft-lbs, then 40 ft-lbs, and then finally 70 ft-lbs. If you are torquing 16 ft-lbs to much or to little, you are setting yourself up for serious problems. You are either going to under torque or over torque your head bolts by 22% versus ARP’s recommended level! Torque wrenches are often used to torque the lugs on a wheel before a car ventures on the track as well. We don’t have to go into a lot of detail here, you can imagine just how dangerous it would be to have a torque wrench that was under torquing your wheel lugs. What To Do If Your Torque Wrench Is Off Even if you take immaculate care of your torque wrench ARP advised us that mechanics should have their torque wrench tested once a year to ensure that it is calibrated correctly. If your torque wrench does happen to be off by a few ft-lbs then what is the best option? “We don’t actually calibrate the torque wrenches that are a few ft-lbs off,” Raschke explained to us. “Most all of the popular tool trucks like Snap-On and others will send the wrench in for calibration. In fact Sears provides service for their torque wrenches.” Torque Wrench Maintenance Tips
- Before each use, inspect the general condition of the tool. Check for loose hardware, misalignment or binding of moving parts, cracked or broken parts, and any other condition that may affect its safe operation.
- After use, wipe external surfaces of the tool with clean cloth.
- If the Torque Wrench has not been used for some time, turn the knurled handle (clockwise and counterclockwise) several times to re-lubricate the internal workings. Then, operate at a low torque setting several times. This ensures proper operation.
- Do not turn knurled handle below the lowest torque setting.
- Wipe Torque Wrench with a cloth to clean. Do not immerse in any cleaning solution. This would damage the internal lubrication.
- Periodically have the Wrench calibrated and serviced by a qualified technician.
- Store inside case in a clean and dry location.