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

[2006Tahoe2WD]

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.

Auto things: pulling two things together e.g. wheel and hub and head bolts. These are considered "flat" items being pulled together. So sorry I can't agree with you. I see what you are saying but I haven't seen instructions that align. I'm talking about the final torque value e.g. on a head. Most of the time there are preliminary steps. E.g. torque to 60 then 80 then 100 or something like that. I haven't seen where going back and retorquing to 100 is specified. I could be wrong but I have seen that called out.

 

[hagar]

Auto things: pulling two things together e.g. wheel and hub and head bolts. These are considered "flat" items being pulled together. So sorry I can't agree with you.

If they are flat, try torquing a cylinder head or manifold from the outside in and see how that goes. How about gasket squish as another factor? Even if the cylinder head and block were dead flat (which they are not,) you still have compression from the gasket. Are you saying that if you torque a cylinder head to 50 foot pounds in sequence, and in only one pass, that when you go back to the center head bolts, they are still 50 foot pounds? I have never seen that be the case ever. The center bolts can always take more turn to hit their torque limit again.

 

[2006Tahoe2WD]

I'm not saying that. I'm saying if e.g. you torque your wheels to 140 ft-lbs (2006 Tahoe) using the proper technique. If you go back and attempt to torque or "check" at the 140 ft-lb setting the nut/bolt will not move.

 

[homesick]

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.

Most [maybe all] of my torquing, both military and civilian, has been with multiple fasteners for the assembly being torqued, so I probably meant that.

Even with a single fastener, though it doesn't seem strictly necessary, I think I'd probably double check.

joe

 

[homesick]

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.

I know guys who have always gotten away with relying on their 'elbow torque'.

There have been times when I torqued like assemblies so often that I could score near misses by feel, but the wrench is still better than the elbow.

joe

 

[bigdog9191999]

So for me it depends on what I am doing. Something like heads I like to be a little more "proper.". But most other things. Ehh.


I have four that having them close to even to be more important that 100% for average use. Something high end like say top fuel, NASCAR, Baja trophy truck. Sure I would probably be a little more picky. But when the OEM spec reads "between 40-80ft/lbs how critical is it really? As long as they are all close to the same. Besides most torque wrenches allow for variance, the cheaper the wrench the larger the gap. And let's face it how many of us have high dollar torque wrench, or more importantly when was the last time someone sent one in for calibration?

We have used this basic philosophy drag and circle track racing and to my recollection we have have very very few or no failures from a fasteners in that way. Snap some connecting rods, bend some pushrods sure, but what do you want for beating used stuff for more than it's worth.



Wheels I like to be more even, for obvious reasons. I don't care if they are 100% correct spec. Close and even are more important. That being said my electric impact does a darn decent job of being even ( have "verified" with my hf torque wrench). I got in the habit of using a wrench at my hous because my small compressor and impact were too all over the place putting tires and wheels on.

 

[homesick]

So for me it depends on what I am doing. Something like heads I like to be a little more "proper.". But most other things. Ehh.


I have four that having them close to even to be more important that 100% for average use. Something high end like say top fuel, NASCAR, Baja trophy truck. Sure I would probably be a little more picky. But when the OEM spec reads "between 40-80ft/lbs how critical is it really? As long as they are all close to the same. Besides most torque wrenches allow for variance, the cheaper the wrench the larger the gap. And let's face it how many of us have high dollar torque wrench, or more importantly when was the last time someone sent one in for calibration?

We have used this basic philosophy drag and circle track racing and to my recollection we have have very very few or no failures from a fasteners in that way. Snap some connecting rods, bend some pushrods sure, but what do you want for beating used stuff for more than it's worth.



Wheels I like to be more even, for obvious reasons. I don't care if they are 100% correct spec. Close and even are more important. That being said my electric impact does a darn decent job of being even ( have "verified" with my hf torque wrench). I got in the habit of using a wrench at my hous because my small compressor and impact were too all over the place putting tires and wheels on.

How can 'close and even' ever be better than 'exact and even', which is what '100% correct' means. Some folks call that "crazy talk".

As a reminder, the original post specified a particular final torque, not a range of final torques.

joe

 

[exp500]

Reading most engineering specs for Aircraft, You will find a spec for the wrench- usually 2 percent accuracy (hard to find one that will maintain that over time. We had favorites). Further reading in the assembly instructions will be torque sequence and procedure with specific partial torque steps, usually 3.

 

[Blackcar]

Reading most engineering specs for Aircraft, You will find a spec for the wrench- usually 2 percent accuracy (hard to find one that will maintain that over time. We had favorites). Further reading in the assembly instructions will be torque sequence and procedure with specific partial torque steps, usually 3.

Quality control in auto, aircraft manufactures should be calibrating torque wrenches and gages at certain intervals.

 

[OR VietVet]

Quality control in auto, aircraft manufactures should be calibrating torque wrenches and gages at certain intervals.

They better be.

 

[hagar]

They better be.

Hahahha! That sound of something metal bouncing off the road as you make your first turn after replacing something, takes on a whoooole different meaning when you are in the air, for sure....

 

[hagar]

Most [maybe all] of my torquing, both military and civilian, has been with multiple fasteners for the assembly being torqued, so I probably meant that.

Even with a single fastener, though it doesn't seem strictly necessary, I think I'd probably double check.

joe

One thing you will notice when you get used to setting a bolt to a certain spec, is that you can actually feel your arm come up on tension, as you approach to set torque. I started off millwrighting and learned the feel of things like many. I still won't torque anything critical without being to perfect spec. Just spend 200 bucks and get the bolt dialed in to its sweet spot on every part of your engine, and you will have a great chance for a good engine.

 

[homesick]

Hemmings has a newly updated, pretty technical, in-depth story on fasteners and torque...

joe

https://www.hemmings.com/stories/how-to-properly-torque-fasteners/?uemlid=9cf30c1e7a49d1549709dd959c28d27086e567feb2ba7a11e442b88acbafe6a3