Originally Posted by Rzeppa
That is not proper operation of a lunchbox locker. Proper operation is a nice "click click click". Lots of people have come to assume that the loud bang when it locks and then unloads is "normal". It is not.
Since I wrote that article for Toyota Trails about 10-11 years ago about Lock Rights in Land Cruisers, I have learned more. Among them, that there is a bit more to it than simply having clearance between the couplers that is within specification. Two other critical parameters for proper operation are having the entire 3rd set up properly (pinion depth, preload, carrier bearing position and preload) and secondly using 140 wt as recommended by the manufacturer.
ARB and Detroit installs are ALWAYS accompanied by a WHOLE NEW 3rd MEMBER SETUP, and therefore any issues with the existing setup are completely obviated. I discovered this around 2004 when I rebuilt my rear 3rd in my '71 '40. The before and after with the Lock Right was like night and day. No more booms and bangs that I had thought just went with the territory. I also started paying attention to the fact the the instructions recommend 140 wt, which does seem to help.
If you have a lunchbox locker that booms and bangs, obviously the first thing to check is the clearance between the couplers, which is set by the thickness of the thrust washers. If it is within spec, then check all the important measurements of the pinion and carrier. And of course, use 140 wt.
Well, I set up a lot of rear ends and I know mine was done correctly and the locker still behaved exactly as I described it above. Now, it was a used unit so were the cogs worn causing it to let loose occassionally? Maybe, but I have also talked to lots of other folks who have experienced the same behavior.