installing a m416 lunette

[tjrubicon]

hey guys how tight does the castle nut go? i have tried googling but have not come up with anything helpful, should i be able to rotate it by hand? do i use a tq wrench? i have not installed one before but my hook is showing up today!

 

[I Leak Oil]

With all the washers and spring in place I've always tightened it enough to get the cotter pin in. Turning it by hand or not might depend on how manly you are!

 

[JPNCA]

2nd that

 

[/dev/ram]

Cotter pin insertion rule #42... although I have say that it makes the lunette very tight. It will turn, but only under duress - which is fine if you're using the pintle ring and hook. Keep it greased well.

I run a multi-axis hitch, so have made mine a bit looser and installed a second nut (a stover nut in fact) behind the stock one. I can turn my lunette by hand (with a little umph) which suits my purpose.

 

[tjrubicon]

in the army book it mentions something about using a feeler gauge? if i tighten the spring to that spec i do not think it would move at all. i just dont want to test the safety chains out if i dont get it right but i would like it to rotate freely when off camber.

 

[Kflash]

I went through the same head scratch when reinstalling mine. You need to be able to slip a tin feeler guage between the coils. On my original spring, I could achieve this and have the cotter pin fall just right in the castle of the nut and the hole for the pin. However, I had ordered a reproduction spring from frontlinemilitary.com (FLM.com) and wound up with a different situation. When tightening the spring for the same feeler guage setting, the hole for the pin was well beyond the castle of the nut and would be non functional. When bringing it up to FLM, they swore the spring was correct and was made to spec, but it just wasn't the case - it was clearly different. If I only tightened it to the same depth as the original, it would have had 1/8 gaps between the coils. I cleaned up and reinstalled my original.

If anyone wants the new spring, I'll sell it for $10. I am sure it is correct for some, but perhaps not all versions of the threaded portion of the lunette.

 

[tjrubicon]

hey thanks for the pic, i have 2 springs and i will keep that in mind when i tighten it down. just need to get a 1-5/16 socket now.

 

[tjrubicon]

i installed it without the flat washer against the casting, i could not get the cotter pin in without the coil fully compressed it is this way on both of my springs, i see no reason for it to be that tight.

 

[I Leak Oil]

Grind a little off each end of the spring to account for the thickness of the washer. You can then install the washer and avoid the spring cutting into the casting if it rotates with the lunnette. Or another option is to drill another hole for the cotter pin and install as usual.

 

[tjrubicon]

thanks for the tip, it was so tight with both washers in that i could hardly move it with a 3ft pry bar. with one washer in i can move it by hand if i try hard and the cotter pin goes right in, it seems tight and looks like the spring will actually compress a little instead of the coils touching each other. i have a bit more gap than in the picture above i dont see how a spring compressed that much is going to do anything at all.

 

[I Leak Oil]

The spring isn't there as a shock absorber type of mechanism. It's there to provide enough pressure on the taper to allow it to be tight but still rotate. Just a simpler, easier way to produce than, for example, a set of tapered roller bearings. You don't want the taper coming apart and pounding itself into oblivion! Too much of a gap in the spring can be detrimental over time.