Stuff We Use: Torque Wrenches

On our never-ending quest to improve this place by listening to feedback from the B&B, we are taking a new tack with these product posts, choosing instead to focus on items we have actually used or purchased with our own meagre income. After all, if we’re giving you the truth about cars, we ought to give you the truth about car accessories.

Making sure to properly tighten various and sundry bolts on one’s vehicle is a blindingly critical part of DIY, helping prevent the hilarity of wheels suddenly leaving the chat or a valve cover failing to do its job properly.

That’s why torque wrenches were invented. For anyone new around here or simply not in the weeds of do-it-yerself car repair, torque wrenches look markedly similar to a common 1/4 or 3/8 drive ratchet wrench that comes with a standard socket set – just with a much longer handle. Us old timers might also reference the so-called breaker bar which was essentially a non-ratcheting socket wrench whose enormously long handle permits the application of a massive amount of torque. Your author used to call it ‘The Persuader’.

But despite their outsized appearance and similarity to brute force tools, the modern torque wrench should be treated as a precision instrument. Most fasteners on a vehicle (whether the lug nuts on a wheel, bolts on a cylinder head, or fasteners on a brake caliper) have some sort of torque spec to which it should be tightened. These specifications help prevent over- or under-tightening, neither of which are good things in the assembly of a car.

Torque is generally understood to be a force and a distance, explaining why it is most commonly expressed in newton-meters or pound-feet. This measure isn’t restricted to the grunt hove out by an engine, though that is the most frequent use of the term known to gearheads and non-car people alike. For example, the tightening spec for a set of lug nuts could be 80 lb-ft for each of the five or six fasteners. It is important to get this stuff right for safety reasons, which is by reputable tire shops that know what they’re doing will tell their customers to return after a hundred miles of driving post-changeover to get their wheels ‘retorqued’.

A good torque wrench from a place like eBay will permit its user to do just that. Generally, the base of the wrench’s handle will have a series of numbers etched into its face. Part of that same handle should be moveable, usually by twisting, allowing the user to select the maximum amount of torque they wish to exert on a fastener. Once that level is reached, the torque wrench should stop ratcheting and simply make a clicking sound; this is how it prevents overtightening.

Yes, your Uncle Walt probably says he knows exactly how much grunt to put into tightening lug nuts without a torque wrench. Play it safe and don’t listen to him. A ‘medium grunt’ is not really an approved measure, nor is ‘two ugga duggas’ or just letting an air impact gun hammer away until all the beer is gone. Torque wrenches make life easier in this regard.

Slightly more expensive are torque wrenches which have digital readouts on their handles, permitting users to dial in the precise amount of torque required for their project. This is especially helpful when dealing with really important specs (think engine assembly) or items which have torque recommendations given in pound-inches when pound-feet is too high for the precision fastener. There are plenty on marketplaces like eBayMotors for less than a hundred bucks.

Most good torque wrenches are shipped in a blow-molded plastic case. This may seem like overkill and it can be extremely temping to toss it out in the name of fitting everything into yer increasingly crowded toolbox. Don’t. The risk of damaging the torque wrench and throwing it out of alignment is too high; if that happens, the wrench might not torque correctly to the requested value – which is the whole point of this thing in the first place.