Torque talk…bolting and tools this time, not performance

[Dave]

The other day I fitted bar risers to one of my bikes.
Being the good boy I am , especially at following instructions , this time I used the torque wrench due to the alloys involved.

When removing the manufacturer installed bolts, I used the torque wrench (set at the figure supplied for the new bolting), and just as I was applying the farce the existing bolt moved.
“that was not as tight as I expected” went thru my mind…then the other three bolts moved with similar effort, all before the wrench clicked.

When fitting the new bolting, screwing in to finger tight, then nipped up before applying the final farce, the wrench clicked just slightly above the effort required for undoing, but not much.

Then I got to thinking about last year when fitting a bike rack to the tow bar of a car, again I was a good boy and followed guidance by using the torque wrench at the specified setting, and again it clicked far too easily.
But that time I disregarded the torque wrench and got the big bar out and put in the “proper” farce. That was when I had spare bolts, and the farce was going onto a nut, not a machined component.

Recently I read that some of the bolting on my bike are “one use aluminium bolts”…another good reason to do a bit of research and read instructions.


Tip from this post…follow the instructions supplied when tightening up fixings

[Dickie]

Why bother using a torque wrench to remove the old bolts?

[willian]

I hope you wore gloves Dave, hate to think of your office hands getting dirty :D

[al]

Why bother using a torque wrench to remove the old bolts?

I guess he was putting German efficiency to the test.

[Dave]

Why bother using a torque wrench to remove the old bolts?

To get an idea of the farce they used to fit them, to compare with the instruction for the new bolting.

[Dickie]

Why bother using a torque wrench to remove the old bolts?

To get an idea of the farce they used to fit them, to compare with the instruction for the new bolting.

What did you conclude after taking out the old bolts and how did that conclusion help influence your course of action when fitting the new bolts?

I'm hoping I'll learn something here. I usually remove an old bolt or nut and move onto the next step without really giving it a second thought.

[Dave]

Why bother using a torque wrench to remove the old bolts?

To get an idea of the f0rce they used to fit them, to compare with the instruction for the new bolting.

What did you conclude after taking out the old bolts and how did that conclusion help influence your course of action when fitting the new bolts?

I'm hoping I'll learn something here. I usually remove an old bolt or nut and move onto the next step without really giving it a second thought.

I know what you mean with normal bolting, but for me this is relativity new territory fafing with new expensive bikes and alloy materials on a component that I am holding onto with my life.

I expected to see thread lock on the instructions for the new bolting...but no.
So i was sort of hoping to see threadlock when removing the original bolts...but no.

I am a mechanical engineer, and understand the theory and different characteristics of many materials.
I deal with engineering vendors and sales people on a daily basis...very rarely do I fully trust them, and often I challenge their claims and literature, only to have a response like "we have never been asked that one before" then often help/guide then thru technical approvals, often with international verification bodies.

My grandfather had a smiddy, and a motor garage, my father a master builder, i grew up using the "feel" with mechanical and masonry materials,..which is very different from the science.

So when dealing with alloy materials manufactured to fine tolerances, sometimes, well almost always, the effort required to make bolted connections often feels a bit light for me.

Basically, I rarely take anything on face value, including many of my first impressions, hence my desire to know what effort the original manufacturer used in installing the first bolts, compare it with what the after market vendor recommendation for fitting the new bolts, compare both with my knowledges and experience and hope all are within a suitable tolerance.

With the bar risers for the B_M_W S1000RS...I accepted the vendors figures after knowing the effort required to remove the original bolting and the research I did on standard bolting with the materials involved.

With the grade 8.8 bolts used for the car tow bar...feck the recommended torque which is suitable for using into a softer alloy or casting, and just horse up those big bolts into those nuts as I know I cannot strip those threads or shear those big bolts just using a 0.6m long bar.

[willian]

Rig tight, that's what it should be!

Will soon see if your torque wrench was calibrated correctly

[Dickie]

Basically, I rarely take anything on face value, including many of my first impressions, hence my desire to know what effort the original manufacturer used in installing the first bolts, compare it with what the after market vendor recommendation for fitting the new bolts, compare both with my knowledges and experience and hope all are within a suitable tolerance.

I expected to see thread lock on the instructions for the new bolting...but no.
So i was sort of hoping to see threadlock when removing the original bolts...but no.

These two statements don't really add up. It looks like the aftermarket vendor has taken the exact same approach to fitting the replacement bolts but for some reason that didn't seem right to you. If you're really that concerned you could always go and buy a tube of the stuff.