Bolt torque (overthinking it?)

teK--

teK--

Eats Squid
RB brainstrust and nerds please!

Due to concerns with galling, I am planning to replace some stainless steel (316 grade) suspension pivot bolts with Grade 12.9 steel bolts.

After reading this site: Torque to Bolts article, it seems I may need to adjust the torque spec to suit the new bolts, to ensure enough clamping force?

To put it into context, the stainless bolts were rated at around 85,000psi tensile strength, and the steel ones are 180,000psi. The site suggests you ideally stretch any given bolt to 75% of their tensile strength to reach what they call clamp load.

Inputting the stainless steel bolt specs to the formula on that site, results a recommended tightening torque spec of 13.44Nm... Not too far off from the bike manufacturer's spec of 13Nm (for the stock stainless steel bolt).

If I input figures from the 12.9 grade steel bolts, the formula suggests a figure of 30Nm which seems awfully high and will presumably cause other issues with the swingarm assembly.

What if I just stick to the stock spec of 13Nm with the new steel bolts???
 
fjohn860

fjohn860

Alice in diaperland
Are the stainless steel bolts being threaded in to stainless steel? If so I can understand your fear of galling. If it's aluminium, I've never had an issue with galling.

As far as the 30nm (an increase of 16.56nm :oops:) if it's an aluminium frame or AL inserts that is definitely flirting with a visit to the COTFW thread IMO.
 
teK--

teK--

Eats Squid
fjohn860 said:
Are the stainless steel bolts being threaded in to stainless steel? If so I can understand your fear of galling. If it's aluminium, I've never had an issue with galling.

As far as the 30nm (an increase of 16.56nm :oops:) if it's an aluminium frame or AL inserts that is definitely flirting with a visit to the COTFW thread IMO.
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Threaded into aluminium, and with grease. I too thought galling wouldn't be an issue, until one day a bolt gave a squeal before it reached proper torque, and the head snapped off! Never again.

Mattyp said:
Before Dale's gets in with an essay on bolt specs from 1963, I would definitely not exceed manufacturers specs on the frame.
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Tend to agree with you. Happy for @Dales Cannon to submit his thesis complete with citations though :D

The part that doesn't make sense is for every bolt to require stretching to 75% of its tensile strength in order to clamp effectively. I would have thought the required clamping force is determined by how the joint is designed/used, and that you can use any size or material bolt so long as you stay within the limits of its tensile strength.
 
slowmick

slowmick

38-39"
what is the bolt doing? do you really need clamping force? If it is an axle for a bearing it's the clamping force required just enough to stop the centre of the bearing spinning?
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
The tension is specific to the frame and connection not the fastener. As Mark has said just use the same torque and forget about it. Of course you could continue to use sus bolts and just use a decent antiseize. Realistically though the best fastener for that application is depleted uranium with chocolate sprinkles on top.
 
link1896

link1896

Mr Greenfield
teK-- said:
Thanks Mark and all you other legends!
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You’re most welcome, Dales will have even more insight to add about varying loads, etc. bolted connections are his forte.

Do you have some photos of the broken bolt and the location in the frame?
 
teK--

teK--

Eats Squid
slowmick said:
what is the bolt doing? do you really need clamping force? If it is an axle for a bearing it's the clamping force required just enough to stop the centre of the bearing spinning?
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Good question.

The bolt pulls together two cones inside a barrel that has a wedge internal profile. Basically like this (it shows the removal tool in place of the usual fixing bolt, but you get the idea):

Clipboard01.jpg
 
link1896

link1896

Mr Greenfield
slowmick said:
My goodness the engineers got carried away with that one.
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Yes but the bearings aren’t in blind holes. That is a plus. Carbon frames with blind or 3/4ers blind holes where the frame opening behind the bearing is a shade larger then the bearings inner diameter are truely evil when it comes to removing old bearings.
 
slowmick

slowmick

38-39"
link1896 said:
Yes but the bearings aren’t in blind holes. That is a plus. Carbon frames with blind or 3/4ers blind holes where the frame opening behind the bearing is a shade larger then the bearings inner diameter are truely evil when it comes to removing old bearings.
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I assumed that the bearings were in a linkage. If so the whole tapered black thing could be replaced with a nut, bolt and some funky washers.
But my background is simplicity to manufacture. Most things I designed in my old job were based on 150PFC, 16mm bolts and 50x50x6 angle as they were always available in the store.
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
slowmick said:
I assumed that the bearings were in a linkage. If so the whole tapered black thing could be replaced with a nut, bolt and some funky washers.
But my background is simplicity to manufacture. Most things I designed in my old job were based on 150PFC, 16mm bolts and 50x50x6 angle as they were always available in the store.
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Early days of my first job one of the fitting apprentices broke his foot playing a weekend sport. Contact tiddliwinks or somefink. He was moved into the drawing office for six weeks or so and during that time had to draw a new tool cabinet for the mills and lathes with a bench to sharpen tools, layout small jobs etc. Pretty big unit. He designed it in modules using the steel stock on hand 50mm rhs, 1.6t sheet etc. Got built. The whole workshop saw bits being fabricated and the day came to bolt the subassemblies together and put the doors on, drawers in and so on. Whole shebang was on casters. Had to move it a few hundred mm into place. Forklift couldnt budge it. It was then found that the new set up weighed over 10 tonnes!
 
teK--

teK--

Eats Squid
Dales Cannon said:
Early days of my first job one of the fitting apprentices broke his foot playing a weekend sport. Contact tiddliwinks or somefink. He was moved into the drawing office for six weeks or so and during that time had to draw a new tool cabinet for the mills and lathes with a bench to sharpen tools, layout small jobs etc. Pretty big unit. He designed it in modules using the steel stock on hand 50mm rhs, 1.6t sheet etc. Got built. The whole workshop saw bits being fabricated and the day came to bolt the subassemblies together and put the doors on, drawers in and so on. Whole shebang was on casters. Had to move it a few hundred mm into place. Forklift couldnt budge it. It was then found that the new set up weighed over 10 tonnes!
Click to expand...
My recent experience was almost as bad...

Ordered a new work/tool bench online, said I would pick up as they had in stock.

Waited a week still no confirmation it was ready so I rang them. They said it was buried in the back of the warehouse and blocked in by all this other stuff. Offered for me to have the unit that was out on the showroom floor. I declined and said I want the boxed one and was met with much swearing.

Next day I rocked up with a removal van that we rented. They had to forklift this crate into the truck, and it was only then that it occurred to me... how the hell are we going to unload this at the house?

Ended up stripping off the crate sides which saved 60Kg alone, but still 190Kg to contend with.

We removed all the shelves and other loose bits. With a couple of blokes was able to flip the heaviest section on its back so the caster wheels could be installed, but not without denting one corner when we dropped it (nothing some home panel beating didn't fix). Finally wheeled it off the truck using the inbuilt lift.

That whole process took good part of an hour. Spent the next 4 hours rushing like mad to complete the house move before we had to return the van.

Time not included in that hour is assembly of the bench, cutting up all the crate timber pieces for hard rubbish pickup, and picking up all the staples and nails that fell on the driveway.

Lesson learned was I should have just accepted the display unit... :D

20221118_083753.jpg
 
Dales Cannon

Dales Cannon

lightbrain about 4pm
Staff member
teK-- said:
My recent experience was almost as bad...

Ordered a new work/tool bench online, said I would pick up as they had in stock.

Waited a week still no confirmation it was ready so I rang them. They said it was buried in the back of the warehouse and blocked in by all this other stuff. Offered for me to have the unit that was out on the showroom floor. I declined and said I want the boxed one and was met with much swearing.

Next day I rocked up with a removal van that we rented. They had to forklift this crate into the truck, and it was only then that it occurred to me... how the hell are we going to unload this at the house?

Ended up stripping off the crate sides which saved 60Kg alone, but still 190Kg to contend with.

We removed all the shelves and other loose bits. With a couple of blokes was able to flip the heaviest section on its back so the caster wheels could be installed, but not without denting one corner when we dropped it (nothing some home panel beating didn't fix). Finally wheeled it off the truck using the inbuilt lift.

That whole process took good part of an hour. Spent the next 4 hours rushing like mad to complete the house move before we had to return the van.

Time not included in that hour is assembly of the bench, cutting up all the crate timber pieces for hard rubbish pickup, and picking up all the staples and nails that fell on the driveway.

Lesson learned was I should have just accepted the display unit... :D

View attachment 398681
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A mate bought some Milwaukee cabinets. Sounds like a similar story. Got them delivered in cases. No drop deck truck. Bugger. Man handled it out of the van and stripped the cases. Casters weren't installed so used a trolley jack to lift the end. What a bugger of a job. Sympathies.
 
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