SK Torque WrenchesThe remnants of an exhaust system dangled beneath the ancient bumperless BMW as a clean-cut kid approached the grizzled shop owner. "Sir, I'd be willing to work for you if I could use some tools to fix my car," the kid said, "I won't take too long, and I'm a good worker."
The shop owner cast a hairy eyeball over the tired, primer-spotted Bimmer in front of his door. He could see the kid was doing his best to fix up the car. Plus he knew a good deal when he heard one. "Okay," he said, pointing over his shoulder with his thumb, "For every hour you spend on the car, you owe me an hour and a half cleaning parts in there. If you hurt yourself I don't want to hear about it from your parents. And you have to work outside; I don't want that rusty exhaust system all over my clean floor."
The kid said, "Oh, it's not the exhaust, um, well, it needs that too. I have to replace the front calipers-no brakes!"
"Whatever. Do it out here."
Later that day, as I was standing on a four-way lug wrench (none of those four ways being the correct 19mm size) tightening my lug bolts to the specification for the USS Missouri propeller shaft nut, out ran the shop owner. "What the hell are you doing! Unsnug those lugs and use a torque wrench, for crissakes! Kids...grumble, grumble."
A torque wrench?
Thus began my long and sordid dalliance with the world of shop-level, do-it-yourself BMW service at the same time I was introduced to the torque wrench.
"Torque" in this case relates to the amount of tightening force exerted upon and by a fastener, such as a bolt or a nut. A torque wrench employs an adjustable torque-setting mechanism and/or a built-in indicator to limit or display the amount of torque applied to a fastener. Most torque wrenches will "click" when the preset torque is achieved. You know where to set the torque adjustment on the wrench by reviewing the tightening torque specifications in the repair manual for the car you're working on, and there is also a table of "standard torque specs" broken down by fastener size and grade.
Do-it-yourselfers tend to overtighten fasteners in the absence of a torque wrench-most stuff doesn't need to be that tight. This is the cause of many stripped threads and seized fasteners.
On European cars, there is usually a torque spec for almost every fastener in the car. Most of them are somewhat superfluous-correct torque for a trunk-hinge bolt, for example. However, where things such as wheel lugs and engine assembly are concerned, proper torque is very important if not critical. If you're going to work on cars, you need a torque wrench.
There are torque wrenches available in 1/4-, 3/8- and 1/2-in. drive. Depending upon your own level of automotive addiction, you might need one, two or all three. If you're only going to buy one, buy a 3/8-in.-drive unit. They cost a lot for a good tool-this is one of those cases where you need to spend some money. A cheap Chinese torque wrench isn't going to help if it's not accurate, and I wouldn't trust it to be accurate. For years, I've been using SK torque wrenches, which are medium-priced in the industry.
We're featuring three SK torque wrenches. The 73008 is a 1/4-in. drive, 16 to 88 lb-in., screwdriver-type torque wrench useful for very low-torque fasteners. This unit lends itself to very fine-scale assembly, but you'll use it more often than you think. It is also the most expensive at a street price of $250. The common unit most people should have is the 74100, a 3/8-in. drive, 10 to 100 ft-lb tool, which will have the broadest use potential. It goes for about $120. The 74251 is a 1/2-in. drive, 25 to 250 ft-lb torque wrench, useful for large fasteners such as crankshaft nuts, cylinder-head bolts, wheel-hub nuts and the like. It'll set you back about $150, but if you can do some of these big jobs yourself you'll easily save more than the cost of the torque wrench that enables you to do the job right.