Tail gear box

[waygone]

I have an Intrepid EB with about 2 gallons through it so far, I'm having a problem with the two short bolts that hold the gear box into the boom. About every 2 flights or so they loosen up enough that I can turn the gear box from side to side. Knowing this I keep a very close eye on them, but is there something that can be done to keep them tight. I am hesitant to over tighten them because it won't take much to strip the threads. Should I use red locktite?:dontknow

[phoneman]

Make sure to clean the bolts to remove any oil--run some alcohol into the threads to get any oil out of there also--use blue locktite--it will hold without any problems as long as you get the threads clean AND you don't have any other issues ( as in any unnecessary vibration )

[SeaHawk]

the original bolts are 3mm. You are having a common problem that many have experienced. If tightened correctly, the way Bergen designed/intended, they are supposed to work fine. However, most of us 'gorilla grip' them in (over tighten) and, I believe, pull the steel bolt through the softer aluminium threads they bolt goes in.
I have fixed this by getting a 4mm tap and using a 4mm bolt. I cut the 4mm bolts off short enough that it does not hit the spacer which allows you to set the gear mesh. Chris Bergen recommends this path. I'm a bit paranoid and on my last mod, actually put 4, 4mm bolts in, but two have also held up well on my other bird.
Some thread through the spacer. You can do that, but Bergen doesn't recommend because you lose ability to set gear mesh. I can tell you from experience, the first method I mention works.

[flyingrhino]

You might first check to see if the bolts are not too long. If they bottom out on the spacer they will not stay tight. I went with a 4mm bolts and threaded the spacer also after, and only after, I was sure the gear mesh was set. I have the means to make new spacers so I was not concerned about the loss of ability to set gear mesh.