Zinc, Cadmium, or other?

[laverdas]

you must troque the joint up to the correct valve this depends on the flange size eg 6" 600# will be marked on the drawing and this will be logged in the broken joint register and so on. But in the uk you can't just flog it up to whatever you think is tight because you must sign to say you have done the joint up to the valve in the register and now i'm going for a little lie down

 

[MotoJouni]

There is also tension meters available nowadays. It tells the tension no matter what the torque is. The target is still to get a correct tension, not a correct torque. I have thought those are used for critical joints (in such as power plants) in where the price is not an issue.

 

[laverdas]

tension / torque and material and size and lenght and pounds rates and shed size of pipe its all on the pipe drawing and register ffs

 

[MotoJouni]

Bolts shouldn't be loaded in shear mode. If a bolt is subject to shear, the joint is either too loose, over-loaded or poorly designed in the first place, and you could end up with bent bolts and other damage. Nearly all bolted joints are designed so that the bolts carry tensile load only.

With the caliper mount example, the shear force between the caliper and fork leg is held by the friction between the mating surfaces, not the bolts. So it shouldn't matter if the threaded part or the un-threaded shank of the bolt passes through the joint plane.

There are some instances where a bolt is loaded in shear (shackle pin for example) but such applications are the exception rather than the rule.

Yes that's true. I have understood that this solution (full length thread) is not kept acceptable on some joints on lifting apparatuses for example. If it is that kind of bolt joint that it has high lateral force and would make a disaster if it fails. On normal operating conditions the friction keeps the joint together, but if something abnormal happens the bolt should be able to work as dovel pin. The unthreaded section has more durability than threaded section in that condition. This condition can not be seen from the outside. Sounds quite rare case but I think these manufacturers have prohibited to change full length threaded bolts, and the unthreaded section must have a correct length.

 

[chrisk]

There is also tension meters available nowadays. It tells the tension no matter what the torque is. The target is still to get a correct tension, not a correct torque. I have thought those are used for critical joints (in such as power plants) in where the price is not an issue.

Like this? http://www.elcometerusa.com/Elcometer-BG80TDL-Bolt-Tension-Monitor.html

So in fact, we are measuring the length of the bolt under tension.
And with all this technology, these guys still show a diagram with a total threaded bolt, MotoJouni is not going to be happy! 

 

[sfcpiet]

Like this? http://www.elcometerusa.com/Elcometer-BG80TDL-Bolt-Tension-Monitor.html

So in fact, we are measuring the length of the bolt under tension.
And with all this technology, these guys still show a diagram with a total threaded bolt, MotoJouni is not going to be happy! 

I remember conrod bolts (for plain-bearings) being checked in this manner.  The bolts do need to be precisely made though.

Stretch will occur at the smallest cross-section of a bolt, usually at the threaded part.  Conrod bolts and similar are waisted to allow precise monitoring of stretch.  Just a matter of mathematics from there...

piet 

 

[MotoJouni]

...
So got hold of some professor on one of those Bolting Science websites and asked him the question?

The answer from the professor left us rather crestfallen:
'Just flog the bolts up as hard and evenly as you can' was the verdict!!!!!!!!!!!!!
...

Sounded to my ear if it was just a some dickhead who wanted him to be called "professor".
If you have tools with you can not overtighten the bolts even a littlebit I think you can not then even achieve the correct value. (Too less value for big bolts, or too high target value for smaller ones.)

...
This website highlights that Stainless (A2-A4) needs to be done up tighter to get the same stretch:
https://mdmetric.com/fastindx/TI-168.pdf
...

I'm not sure what you meant, but yes the Youngs modulus is different for different materials and it is not the target to get the same stretch with different materials. At least if it is a strectch bolt, the stretch value is specified on laboratory tests with a highly standardized bolt and even the counterthread must be on the correct location. The dimensions, geometry, material and all sort of tolerances are all highly standardized. The stretch value can not be applied if another kind of bolt is taken.

 

[MotoJouni]

Like this? http://www.elcometerusa.com/Elcometer-BG80TDL-Bolt-Tension-Monitor.html

So in fact, we are measuring the length of the bolt under tension.
And with all this technology, these guys still show a diagram with a total threaded bolt, MotoJouni is not going to be happy! 

Of course I'm happy I think it's also a tensile load only bolt. Those bolts must be highly standardized if the length is measured to achieve correct tension.

Your tightening method sounded one of the most interesting ones I have ever heard:
1. Get tools that are not suitable for the purpose
2. Tighten as tight as you can
3. Measure the length of the bolt
4. Result: wrong value
5. Make no corrective actions
(Joking here, sounded a littlebit if you tried to explain this.)

 

[CLEMTOG]

all I said was..............
the stainless bolts on my Laverda discs are often found to be loose on dismantling and this may be due to them settling, I know the bolt heads haven't turned (tab washers) and I don't think the threaded parts of the bolt have turned either, but loose they are.

A good example of a bolt not being in shear but looking like it (sorry Hag) is the studs/nuts/washers that bolt the chain wheels to the oval flanges on triple camshafts. could even be a perfect example of how 99% of bolts work, what do you say Cam?? and while I am at it, the bolt in shear (as on a shackle) is helped more than 50% by the pin through the eye on the non threaded side, so the shear factor is placed across more than double one bolt thickness,
CLEM

 

[MotoJouni]

Another similar place is how the flywheel is bolted to crankshaft on car engines.

all I said was..............
the stainless bolts on my Laverda discs are often found to be loose on dismantling and this may be due to them settling, I know the bolt heads haven't turned (tab washers) and I don't think the threaded parts of the bolt have turned either, but loose they are.
...

Are those bolts actually stainless originally?

 

[chrisk]

all I said was..............
the stainless bolts on my Laverda discs are often found to be loose on dismantling and this may be due to them settling, I know the bolt heads haven't turned (tab washers) and I don't think the threaded parts of the bolt have turned either, but loose they are.

CLEM

Brake disc bolts On most modern bikes are stepped, for eg: large bolt head dia, dropping down to a 10mm stud that goes through the disc carrier and into the hub a ways, and then M8 thread. And from factory are held in situ by copious amounts of locktite.

 

[Gravelroad]

all I said was..............
the stainless bolts on my Laverda discs are often found to be loose on dismantling and this may be due to them settling, I know the bolt heads haven't turned (tab washers) and I don't think the threaded parts of the bolt have turned either, but loose they are.
CLEM

As I said before, embedding, due to lack of clamping forces, which causes small movements of the clamped surfaces under load. Lack of clamping force comes from stainless bolts having high thread friction figures -> A2-70 half of clamping force achievable compared to 8.8. Any attempt to overcome this by increasing tensioning torque will drive shear stresses through the roof -> bolt rupture.

 

[Davo]

And from factory are held in situ by copious amounts of locktite.

Actually had this discussion with the guy who sorted my frame as well as the stuffed cush drive and rear wheel bearings. He also prepares/repairs race bikes and commented that I had used way too much loctite on the disc carrier mount bolts and then showed me a pack of factory bolts about to go into a R1 - just had a small dash of blue loctite on one side of the bolt.

He made no comment about my use of stainless bolts for this task (perhaps because all the mount holes had been helicoiled) but had removed all the lock washers from under the bolt as he reckoned they destroyed the alloy and hence the integrity of the mount.

There tends to be a lot of conflicting info out there in regard to bolts for purpose etc and I fall into the don't really know who to believe camp. Guess I will ride it as is when I get it back together, until...