Front Brake Disc - Torque Settings for Bolts

[K2-K6]

The original bolts and flange nuts are fine, with no attendant risk as the design and tensile load specifically copes with this application. 

Putting a flanged nut, with no washer is the anti-shake method chosen in place of using lock tabs.

They are held by the bolt being torqued correctly to keep it in tension competently.

You'd not want to swap them for stainless, without knowing details about both material specifications.

[K2-K6]

These type application are usually assembled dry, just the zinc coating on the components and nothing else as part of their function.

[Mikep328]

"They are held by the bolt being torqued correctly to keep it in tension competently.

You'd not want to swap them for stainless, without knowing details about both material specifications."


Yep...An item that is often ignored with fastener "upgrades," is the "self locking" function of properly torqued fittings.  For example, if an OEM fitting uses a grade 2 bolt/nut and someone replaces it with a grade 8 bolt/nut because "it's better," the result will be a fastener that is very prone to loosening because the torque setting in the service manual to properly stretch that Grade 2 bolt will be far too low for the grade 8. 

[Skoti]

"They are held by the bolt being torqued correctly to keep it in tension competently.

You'd not want to swap them for stainless, without knowing details about both material specifications."


Yep...An item that is often ignored with fastener "upgrades," is the "self locking" function of properly torqued fittings.  For example, if an OEM fitting uses a grade 2 bolt/nut and someone replaces it with a grade 8 bolt/nut because "it's better," the result will be a fastener that is very prone to loosening because the torque setting in the service manual to properly stretch that Grade 2 bolt will be far too low for the grade 8. 

Absolutely agree,

and the same applies to stainless fasteners especially on safety critical areas such as steering, suspension and brakes.
 

Had to remove some stainless engine mounting fasteners on my Norton and replace with OEM stuff as they were frequently needing retightened.

Been fine ever since.


Be sure, be safe.

[element137]

Have they got the serrated flange Mick? If so loads available in stainless steel

The OEM nuts are smooth flanged - I did look at using some alternative Stainless Nuts - but they are shallower than the OEM nuts , i.e., the height above the flange to the top of the nut is much higher on OEM ,so less thread would be have been engaged so decided to clean up the OEM bolts and nuts and intend to re-use them - I was curious about the conflicting info about locking tabs or not , and I couldn't find the torque setting anywhere (until it was kindly posted in this thread ( many thanks for that ) -

[element137]

These type application are usually assembled dry, just the zinc coating on the components and nothing else as part of their function.

No thread lock ?

[exvalvesetdabbler]

They would normally have been  nipped up clean and dry.  If you put thread lock or lube on them it  will give you a greater pre load for the same torque setting.  I normally knock  30 % of the torque to compensate if using thread lock or anti seize. Just my rule of thumb, others may have different ideas.

It's the torque and the friction of the flat flange face  that keeps them done up.

Regards
Dave

[K2-K6]

These type application are usually assembled dry, just the zinc coating on the components and nothing else as part of their function.

No thread lock ?

If the manual doesn't specify it, then not necessary to use.

In all practical sense, its not going to make much difference if used, but has the potential to give misreading on torque as it's more "lubricant" than dry only.

What's not immediately clear in design like this is that it effectively locks itself by the bolt threads by  elongation under tensile load, but the nut threads are under compressive load when the flange touches and torque applied. The opposing change in thread pitch between the two making a "lock" nut from that action.
The flange effectively gripping the flat surface under tensile elasticity of the bolt prevents backing out too.

[Oddjob]

That is a point Skoti. I’ve never found the hub carrier to get that hot, even when I was racing the 500, not hot enough to melt the insert anyway but fair point, maybe met locks would be a better choice.

Without the serrations gripping the disc you’re relying on just the torque keeping it in place, not a good idea imo, I’ve had one come out undone, lost the nut entirely. If the bolt had started to come out I could have been in serious trouble but luckily it stayed in place.

[element137]

Thanks all for the very informative replies - I trust Honda's engineering ( even if in this case its 50 years old ) so will go with dry fit and correct torque - really appreciate all the input -

[TrickyMicky]

That is a point Skoti. I’ve never found the hub carrier to get that hot, even when I was racing the 500, not hot enough to melt the insert anyway but fair point, maybe met locks would be a better choice.

Without the serrations gripping the disc you’re relying on just the torque keeping it in place, not a good idea imo, I’ve had one come out undone, lost the nut entirely. If the bolt had started to come out I could have been in serious trouble but luckily it stayed in place.

  Did you ever wonder as to why only one?

[Oddjob]

It was actually 2☹️ I lent the bike to my BIL and didn’t really inspect it when he returned it. A few months later I went to polish it and noticed the missing nut, what was worse was one of the bolts was missing entirely, my BIL hadn’t bothered to mention it so it either fell out whilst in motion or most likely it fell out when parked on the sidestand. The nuts were the flanged Honda ones off a GL1100 as I was running 2 discs. They were all torqued to spec with a Snap On torque wrench. Why 2 came undone is a mystery.

I’ve got my suspicions that it may have been my BIL nicking bits. It came back with tools missing from a brand new toolkit, including the plug spanner. Lots of other bits seemed to have gone as well, just small pieces that are easy to miss until you either want them or spot them missing when you’re cleaning the bike.

[exvalvesetdabbler]

Maybe he's building a bike a piece at a time by nicking bits of yours😀

[Oddjob]

He actually has my K reg 500. He’s had it now about 10 years, he claims I gave it him, which I deny. It’s not worth the aggro tbh, he keeps it on the road and serviced so that’s something but he’s always been jealous of my L reg 500.

[element137]

Maybe he's building a bike a piece at a time by nicking bits of yours😀

Johnny Cash wrote that plan in the song 'One piece at a Time '