Y'all's Thoughts on Torquing Bolts Correctly, Please

[homesick]

Final pass is incomplete until every bolt has reached 65FtLb. Mark each bolts as it achieves spec.

When I used to tighten heads or intake manifolds, I'd wait 15min before the 2nd pass.

I never heard of that, but I think I see the theory. It sure couldn't hurt anything.

joe

 

[Joseph Garcia]

Like @Fless and @OR VietVet, I torque to a lower spec for all bolts, then torque to final spec, and then check one final time to be sure that I got all of the bolts fully torqued. For me, it doesn't matter whether its head bolts or tire lug nuts.

 

[GMCChevy]

Since torque values are specified for a reason, if I am torgueing any bolt or nut, I am going to be sure sure sure. A second or 3rd pass is warranted, in my mind.

A beam style torque wrench is not exact enough. As I said above, if I am going to torque it to spec I am gonna be 100% sure. A beam style can be right on the money or close enough. Why torque at all if gonna be close enough. It is old tech. I believe in the digital/alarm type and then a click type, that may or may not be calibrated correctly.

Beam type torque wrenches are more accurate then click type. The only problem with them is that you need to have a clear view of it so the click type or digital with lights and sound is a lot more convenient. Digital comes down to quality and how well they were calibrated to begin with.

 

[Doubeleive]

i go by what the book says if it says make a pass at xx and a final pass at xx that's what I do.
just don't confuse inch lbs with ft lbs (like I have before) lol

 

[bigdog9191999]

Ohhhh, so I will open this can of worms before I give my answer. ( I will answer later, getting ready for work now).

Is this based just on the mentioned head bolts, or "all" bolts that are supposed to be "torqued" ?

 

[the 18th letter]

Ohhhh, so I will open this can of worms before I give my answer. ( I will answer later, getting ready for work now).

Is this based just on the mentioned head bolts, or "all" bolts that are supposed to be "torqued" ?

I’ve never owned a torque wrench. I’ve also stayed away from work where torquing is required vs recommended, like head bolts as an example.

 

[hagar]

If you are doing something like a cylinder head or intake/exhaust manifold, you will notice that the starting point loosens off after doing the remaining bolts. Torque a cylinder head from the inside out for example to 40 foot pounds to start, then go back to the center bolts with the same 40 foot pound setting, and the bolts will take a decent amount more turn before hitting 40 foot pounds again.
I look at it as trying to get the heads or manifold to lay as flat as possible by forcing the stored energy out of the ends of the head/manifold. I will start by torquing the 2 center cylinder head bolts to 20 foot pounds, then do the 2 on each side of those in sequence, then Torque the center ones again, then release the 2 bolts on either side, then retorque them again, and carry on. Basically just using a lower Torque setting to start, then walking the tension on the head/manifold out the ends. Once you do it once with low torque, the rest of the passes usually click true once you go back and double check the center bolts after torquing the outers.

 

[2006Tahoe2WD]

Umm. "Technically", if the bolt achieved 65 lb-ft, then it shouldn't rotate anymore and you are both correct. Whether he does a single pass, you do 3 passes, and someone else with OCD does 6 passes, it shouldn't matter.

In practice, however, everyone that has used a torque wrench has had at least one faster rotate a tiny bit more at some point, somewhere, some job when going around a second (or third?) pass...and the reason is a bit more technical than one would think.

Assuming the initial torque of 65 was done properly (continuously moving until click) then additional applications with that wrench set at 65 will not move (rotate) the fastener. Reason: dynamic vs. static friction. Additional passes are used to double check that no bolts were missed.

 

[hagar]

Assuming the initial torque of 65 was done properly (continuously moving until click) then additional applications with that wrench set at 65 will not move (rotate) the fastener. Reason: dynamic vs. static friction. Additional passes are used to double check that no bolts were missed.

Not true. The more things that hold something down that is trying to resist being held down, the less effort each thing needs to put in. Bolts can totally lose their foot pound setting after other bolts around it are torqued down. Unless you are bolting 2 perfectly flat things together, but that isn't the case with auto stuff.

 

[ccssid]

Over 55 years ago, my local Harley mechanic told me ( I didn't have a torque wrench) to use a 6", 8" and 12" 9/16 box end wrench at various bolts/ nuts and snug em firm. I never had an issue.