Copper grease and torqe settings

[midlifecrisisrd]

Will be using stainless M6 bolts for the through crankcase fixings so will apply copper grease to stop the reaction, question is how much do I reduce the torque by?

Steve

[tsa]

Answered on other forum mate. No difference.

[Tone]

Seemed to remember reading someone put copper grease on some cam bearing cap bolts thread on a four stroke and ended up stripping the threads when torqueing them up because of the reduced friction of the copper grease.

[midlifecrisisrd]

Oct 11, 2011 17:50:58 GMT 1 Tone said:

Seemed to remember reading someone put copper grease on some cam bearing cap bolts thread on a four stroke and ended up stripping the threads when torqueing them up because of the reduced friction of the copper grease.

That's exactly why I was asking, few people have answered on the other forum saying they don't bother and it was fine. Think it affects it more if you have grease between the head and the mating face as it is the largest contact point so has the most friction.

Steve

[mellow]

just some info from a site i use

It is ESSENTIAL that COPPER ANTI SEIZE compound is applied to stainless fasteners before use and that all threads are cleared of corrosion and debris using a 'plug' or ‘bottom' tap.

Stainless is not generically a tensile material; no form of standard 18/8 or 18/10/3 stainless alloy possesses the tensility of grade 8.8 steel (the benchmark HT std) beware of any claims to the contrary. Many but not all steel bolts fitted to motorcycles are made from high tensile steel principally because HT steel is cheap and easily available. For the same reason ie cost the factories often use flanged bolts (fastener/washer fused together) ie to save assembly time not having to fiddle with washers and spacers etc.

The fact is that with many applications on a motorcycle - fork castings, disc rotor bolts, engine covers etc the material the steel bolts are threaded into is cast aluminium/magnesium alloy. Al/Mg castings are invariably low density and have little crystalline structure - not a feature of high tensile alloy. If you have worked on a Japanese bike you will know how easily the alloy threads 'pull' - again not really the behaviour of something 'strong' in tensile terms. Stainless might not be as tensile as 8.8 but it is certainly way stronger than those alloy threads - in fact often the shear resistance (resistance to cutting action) of stainless is greater than that of tensile steel and Ti. It should be made clear that if for whatever reason you require high tensile fixings you should use manufacturers original equipment.

Stainless steel requires less stretching to enable it to seat. On the assumption any threads have been cleared and prepared properly you should need no more than 66% of the original tensile steel torque spec when tightening.

How far do I tighten stainless screws?

This is directly related to the tensile issue. You don’t need to stretch stainless to get it to seat in the same way as you do with HT. As a rule of thumb use approx 2/3 of the original torque spec. Always refresh alloy threads with a ‘plug or ‘bottom’ tap first to remove oxide and other debris.

Hope this helps ;D

[paulo]

Don't forget to take into account how accurate the torque wrench is that you are using . A torque wrench over time becomes less and less accurate or by simply dropping it on the floor can knock it way out.
The effect of grease between the mating surfaces on a joint is torque drop-off over time. This is the same for any "contaminate i.e. dirt etc.
Grease as an anti seize treatment on S/S bolts on certain applications is OK, like engine assembly etc, but its a no no for safety related applications like caliper bolts etc.
Well that's it, I've added my two penny's worth

[midlifecrisisrd]

Oct 12, 2011 20:16:51 GMT 1 paulo said:

Don't forget to take into account how accurate the torque wrench is that you are using . A torque wrench over time becomes less and less accurate or by simply dropping it on the floor can knock it way out.
The effect of grease between the mating surfaces on a joint is torque drop-off over time. This is the same for any "contaminate i.e. dirt etc.
Grease as an anti seize treatment on S/S bolts on certain applications is OK, like engine assembly etc, but its a no no for safety related applications like caliper bolts etc.
Well that's it, I've added my two penny's worth

Very true,

for anything safety related I use loctite, same result but wont come out.

Steve