Lubricate bolt threads - graphite?
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Fast Eddie
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Yes, that’s my conclusion.
If the threads are in good condition, and factory torque values are used, I suggest lubrication on threads is perfectly fine.
Think I’ll carry on carrying on !
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There are two different issues to be considered with this subject...
1. The physics: putting anything on a fitting that acts as a lubricant - oil/grease/anti-sieze/threadlocker, sealant, etc - increases the tension on the fitting by as much as 50% over a "dry" fitting using the same torque setting on the wrench. That's physical reality.
2. Actual use: It appears that many (most?) folks here use something on threads and factory torque settings with no adverse affect...at least with steel/cast iron fittings. The use of these products reduce/eliminate galling/rusting (or parts falling off!) and general issues that can make future disassembly more difficult.
I use most of the various products and generally don't worry much about the change in actual tension re the torque specs as long as aluminum threads are not involved. As I said, I HAVE seen, and in my younger mechanic-ing days, personally stripped out a few AL threads using factory torque specs/lubricants.
Nowadays, with threads in AL or other soft metals I typically use antisieze and tighten by the "feel" of the fitting rather than using a torque wrench. I'm comfortable doing that and it works well for me. However, I'm not suggesting it's a proper way to do it and I would not suggest that a beginning mechanic use that method.
In fact, if I was teaching mechanics, I'd tell them to follow the service manual...and develop there own preferences as they gain experience.
1. The physics: putting anything on a fitting that acts as a lubricant - oil/grease/anti-sieze/threadlocker, sealant, etc - increases the tension on the fitting by as much as 50% over a "dry" fitting using the same torque setting on the wrench. That's physical reality.
2. Actual use: It appears that many (most?) folks here use something on threads and factory torque settings with no adverse affect...at least with steel/cast iron fittings. The use of these products reduce/eliminate galling/rusting (or parts falling off!) and general issues that can make future disassembly more difficult.
I use most of the various products and generally don't worry much about the change in actual tension re the torque specs as long as aluminum threads are not involved. As I said, I HAVE seen, and in my younger mechanic-ing days, personally stripped out a few AL threads using factory torque specs/lubricants.
Nowadays, with threads in AL or other soft metals I typically use antisieze and tighten by the "feel" of the fitting rather than using a torque wrench. I'm comfortable doing that and it works well for me. However, I'm not suggesting it's a proper way to do it and I would not suggest that a beginning mechanic use that method.
In fact, if I was teaching mechanics, I'd tell them to follow the service manual...and develop there own preferences as they gain experience.
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And properly means tightening enough so they don't fall off, but not too much that they break. Anywhere between that spectrum is proper
Fast Eddie
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Tighten by feel!There are two different issues to be considered with this subject...
1. The physics: putting anything on a fitting that acts as a lubricant - oil/grease/anti-sieze/threadlocker, sealant, etc - increases the tension on the fitting by as much as 50% over a "dry" fitting using the same torque setting on the wrench. That's physical reality.
2. Actual use: It appears that many (most?) folks here use something on threads and factory torque settings with no adverse affect...at least with steel/cast iron fittings. The use of these products reduce/eliminate galling/rusting (or parts falling off!) and general issues that can make future disassembly more difficult.
I use most of the various products and generally don't worry much about the change in actual tension re the torque specs as long as aluminum threads are not involved. As I said, I HAVE seen, and in my younger mechanic-ing days, personally stripped out a few AL threads using factory torque specs/lubricants.
Nowadays, with threads in AL or other soft metals I typically use antisieze and tighten by the "feel" of the fitting rather than using a torque wrench. I'm comfortable doing that and it works well for me. However, I'm not suggesting it's a proper way to do it and I would not suggest that a beginning mechanic use that method.
In fact, if I was teaching mechanics, I'd tell them to follow the service manual...and develop there own preferences as they gain experience.
Goodness gracious. You know what happened to me when I declared using that method doncha ?!?
Fast Eddie
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Actually, those two points are the extremities of failure.
‘Properly’ means that the correct clamping force is applied to the surfaces being clamped together.
Lineslinger
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Yeah, you got vilified for doing what wrench jockeys have been doing successfully for 100 years and more.
When I started swinging spanners quite some decades ago ( BSA Bantam as a field bike ) my mechanic father got hold of some 3/16 and 1/4 bolts and had me clamp them in a vice and tighten the heads until the bolts sheared as a way of learning " feel " ......
Some years later during my apprentice years my fitter supervisor had me tap threads into an alloy casting ( 1/8 3/16 1/4 5/16 ) using both fine and coarse threads and then had me insert bolts of each size into the holes and told me to tighten them until the threads gave way in the alloy, again a method of teaching me " feel ".
All this kind of stood me in good stead over the years as I never stripped a thread on a bike, on a car or in industry ... yay !!!
Lube the threads ? I've done both methods over the years and for me the most important thing is to get everything scrupiously clean before assembly both on internal and external threads with a dry run before final assembly to " feel " how well the fasteners go together, anything iffy can then be discovered and sorted before it becomes an issue in service.
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