Thought I would try and see what the general consensus is on this, as I am a novice mechanic and I have no idea what the right answer is. A few of my more mechanically inclined friends have told me that torquing isn’t all that important for most things and that torque really is only important for certain parts. Is this true? Because when I look in my service manuals for my vehicles it seems like they have recommended torque for most bolts… is this more of a recommendation? Is it okay to just make most bolts “tight’nuff” and call it a day? Interested to see what people’s thoughts are on this.
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Technically, everytime you tighten something you are torquing it. Whether it’s with a torque wrench or by feel. So yes, torquing bolts is important.
torquing is becoming more and more critical as carmakers have shifted to lighter weight components that can be easily damaged by over-torquing. Plus, more and more fasteners on newer cars are torque-to-yield. So if you’re tightening bolts on control arms, struts, brakes, wheel bearings, ball joints, axle nuts, steering components, spark plugs, lug nuts, you’d better be using a torque wrench. Same with all internal engine and transmission parts. If you don’t use a torque wrench on torque-to-yield bolts, you can break them or even crack the component.
DIYers most often overtighten and strip the threads in aluminum engines/heads, especially valve cover bolts, ignition coil bolts, and spark plugs. That’s just plain stupid. Why make your life so hard when torque wrenches are so cheap?
Officially, everything has a proper toque spec. But for an experienced mechanic, there are some things that “good enough” or “by feel” is fine. There are other things that should be properly torqued.
Generally the things that are ok to be “close” on are non critical things, like an interior trim cover, or maybe the antenna mount, or the plastic engine cover. But for things like suspension components, wheels (probably the most common thing you’ll see people torque to spec), cylinder heads, valve/cam/rocker covers, water pumps, and other engine components, those should all be torqued to spec.
On most of the stuff that “backyard” mechanics work on, you can generally develop a feel for what is close, but you run the risk of not having the proper tightness and causing damage. Either from being too tight and stretching/breaking the fastener, stripping the threads, rounding the head or being too loose and having things leak, rattle, or fall off.
If you don’t know, it’s better to take the extra moments to look up the spec and properly tighten it.
Making sure all the bolts on a part are torqued evenly is very important.
Important, as others have said.
My caliper bolts are to be torqued to 135 ft/lbs on the front. If I just used a ratchet and went “good enough” chances are pretty good they would eventually vibrate loose and my entire bracket would end up in my rims or somewhere else causing a lot of damage.
Could I use a break bar and just uga dugga them tight? Ya probably and they would probably be ok for a long time to. Do I want to risk one of the most critical safety aspects of my truck being the brakes? No , no I do not.
Lug nuts are another one. You don’t wanna over tighten those to the point you stretch and break the studs, having catastrophic failure and your wheel coming off on the highway (interstate). Some lugs call for 70ft lbs, some like my truck call for 130ft lbs.
Will it always lead to failure? No probably not. Do you want to risk your (and your friends/loved ones lives?) I’m going to take a guess and say no, probably not.
Tl/DR: invest in a torque wrench and use it. 20ft lbs isn’t much and can be over torqued. 130+ ft lbs is pretty heavy torquing and you’ll never “feel” it out