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Posted: 11/19/2008 5:22:47 PM EDT
| I have read over the barrel installation instructions but am unclear on the torque issue. Do you torque to 80 ft lbs and then loosen and repeat for a total of 3 times? Then what. Do you tighten back to 80 ft lbs? If the gas tube doesn't line up with the barrel nut lugs at that point do you go tighter? |
| Don't even try to get to 80 ft. lbs. Snug it up and back off three times. Your torque wrench ought to have that at right around 30 ft. lbs. The spec is 30-80 ft. lbs. Once you've snugged and resnugged three times, up to the 30 ft. lbs. minimum, just tighten it until the very next spot that you can get the barrel lugs aligned such that the gas tube can be installed. |
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Quoted:
Don't even try to get to 80 ft. lbs. Snug it up and back off three times. Your torque wrench ought to have that at right around 30 ft. lbs. The spec is 30-80 ft. lbs. Once you've snugged and resnugged three times, up to the 30 ft. lbs. minimum, just tighten it until the very next spot that you can get the barrel lugs aligned such that the gas tube can be installed. +1 Most folks don't use a torque wrench. Snug the nut and back off three times and tighten until the gas tube is aligned. |
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What is happening with the multiple torquing passes is the aluminum is getting "lapped" to the steel barrel nut. The aluminum, while having a hard anodized surface, deforms three times as much as the nut. This "seats" the nut to the threads, making a connection with much more surface contact and reducing the chance that the nut will loosen.
Make sure to grease it with a moly only grease, NO GRAPHITE. That means Ford wheel bearing grease is not the right stuff. |
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Or to be even more simple:
Snug the nut (first time) loosen the nut Snug it again (second time) loosen it again Snug it once more (third time) to at least 30 ft-lbs but only enough more to line up the next notch in the nut. If there's a way to say it both more simply and more clearly at the same time, I don't know it. |
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Quoted:
What is happening with the multiple torquing passes is the aluminum is getting "lapped" to the steel barrel nut. The aluminum, while having a hard anodized surface, deforms three times as much as the nut. This "seats" the nut to the threads, making a connection with much more surface contact and reducing the chance that the nut will loosen. Make sure to grease it with a moly only grease, NO GRAPHITE. That means Ford wheel bearing grease is not the right stuff. NO Graphite?!? crap i bought moly grease with graphite because i was stoked it would work with my clutch build and my ar build. i'm glad i read this |
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Quoted:
Quoted:
What is happening with the multiple torquing passes is the aluminum is getting "lapped" to the steel barrel nut. The aluminum, while having a hard anodized surface, deforms three times as much as the nut. This "seats" the nut to the threads, making a connection with much more surface contact and reducing the chance that the nut will loosen. Make sure to grease it with a moly only grease, NO GRAPHITE. That means Ford wheel bearing grease is not the right stuff. NO Graphite?!? crap i bought moly grease with graphite because i was stoked it would work with my clutch build and my ar build. i'm glad i read this Graphite is not good for grease between dissimilar metals, especially steel (the nut) and aluminum (the upper). It takes quite a bit of looking to find an inexpensive grease that has molybdenum disulfide and does not have graphite. I've been using the aviation grease QUIB recommends, AeroShell 33MS, which cost about $15 for a 15oz tube that is so much grease that it will be passed to my grandchildren. |
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Quoted: Okay, I got the same grease question. I went to O'Reilly Auto to pick up some grease yesterday and picked up a small crisco-like can of something called Moly EP Grease. http://doitbest.com/Grease+and+Lubricants-Plews+Lubrimatic-model-11335-doitbest-sku-572311.dibWhat is happening with the multiple torquing passes is the aluminum is getting "lapped" to the steel barrel nut. The aluminum, while having a hard anodized surface, deforms three times as much as the nut. This "seats" the nut to the threads, making a connection with much more surface contact and reducing the chance that the nut will loosen. Make sure to grease it with a moly only grease, NO GRAPHITE. That means Ford wheel bearing grease is not the right stuff. The back says "Recommended for sleeve, ball, and roller bearings, ball and universal joints; not recommended for disc brake wheel bearings. Then is says the BASE TYPE is: Lithium (for us gun nuts) 12-hydroxy stearate. I'm guessing Molybdenum is an additive? Did I get the correct stuff?  I knew how to change the oil in an airplane before I learned so in a car so my automotive knowledge is um...lacking  |
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The Aeroshell 33MS product is what I use (based on recommendations on this forum!). It's available from skygeek.com.
http://www.skygeek.com/5067068.html You'll note that it's fully approved to MIL-G-21164D. Use this and you won't have to guess if you have the right grease or not. |
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