DISCLAIMER: I cannot stress enough that what works for me may not be what works best for everyone. This is a “take it or leave it” thing and certainly not for the most anal of engineers…
LEARN HOW TO TORQUE BOLTS TO SPEC BY HAND
My own personal hand feel variances are only about ~5 lb-ft versus the real spec on the higher spec torques. Yup, I’m achieving that even with my tendinosis and small IQ problem, but that took some practice to achieve. Here’s my tips;
Now, this needs some bench testing on your part. If you’re able to do so, fabricate yourself a plate and either tap or weld nuts with the most common bolt sizes and their normal metric threading (we’re working on Subies here after all). Or try it out directly on your car, I don’t care. It is important that your plate does not move under force, so bolt it on a workbench. You can then start off by torquing a bolt on by using feeling only in increments of 5 lb-ft. Then test it out with the torque wrench to see how far off you were. Careful, some torque wrenches do not have low torque capabilities! It’s harder to tell if you do the opposite method. Also try doing the tests in different work angles because you won’t always be in the same position when actually working on the car. Learn the signs your body tells you and use common sense. Start off by using your elbow power only. It gives more accurate feedback than using any type of leverage with other parts of the body, mainly the legs. The wrist is only useful or needed on very small bolts.
For best results, test out ALL your ratchets of different lengths and size; I always use the smaller 1/4″ ratchet on anything below 8 mm head size, the 3/8″ ratchet on 8 – 10 & 12 mm bolts (14 mm are stretching its capabilities but doable with a small tube extension), and finally the 1/2″ ratchet on anything 14 mm and higher. I have found to be able to accurately hand torque up to about 10 lb-ft with the 1/4″ ratchet, to 30 lb-ft with the 3/8″, and up to 60 lb-ft with the 1/2″. Again it all depends on the handle length of your tool. You can use a tube extension to get more force but I’d never do it unless using the 1/2″ with 6 point sockets. Sure, you could do some fancy schmancy math and calculate that stuff but I’m retarded so I can’t do that! My own personal trick to counter this low IQ is by varying my grip on the handle. By example: since I already know I that can max torque up to 30 lb-ft with my 3/8″ when using full arm force with my hand positioned at the very edge of the handle (more leverage), it is acceptable to think that if I put my hand halfway on the handle that I’ll get around 15 lb-ft until I can’t pull no more!
Try it out, it’s simple and quick! This is particularly useful for the smaller bolts which are not usually torque critical. Losing time to torque those exactly to spec is almost ridiculous, unless it is on a critical component like the engine, drivetrain, or suspension!