I've had issues with a pitts muffler and a DA 60 for two years. I tried everything.....nordlocks, the green loc-tite, wire locking the bolts and nothing worked. I then realized I was trying to fix the wrong problem. The problem wasn't the bolts loosening up but the Exhaust port actually wearing into the muffler thus reducing tension on the bolts. The aluminum on the muffler is softer than the exhaust port material. I had a piece of hardened aluminum plate welded to the muffler and the problem was solved!

A common fix for aluminium softness differences is to use a 0.005" brass shim gasket

Originally Posted by williey78

I've had issues with a pitts muffler and a DA 60 for two years. I tried everything.....nordlocks, the green loc-tite, wire locking the bolts and nothing worked. I then realized I was trying to fix the wrong problem. The problem wasn't the bolts loosening up but the Exhaust port actually wearing into the muffler thus reducing tension on the bolts. The aluminum on the muffler is softer than the exhaust port material. I had a piece of hardened aluminum plate welded to the muffler and the problem was solved!

Been there, done that. I had a muffler that didn't really come loose but wore away over time as you suggested. It also developed a small crack in the exhaust port opening. I welded a 1/8" or 3/16" 6061-T6 plate (don't remember exact thickness) over the port location and if you notice also added a threaded pad to the can for a support strap back to a cylinder retaining bolt. Modified this way, these things are bullet proof! I know mods like these are not approved or recommended by Jtec but I feel it improves the product, at least for me. The aluminum was salvaged from an old TnT landing gear.

Edit: Just adding the support strap on the can stops the erosion between the exhaust flange mating surfaces and aids keeping the muffler tight. The mod is all on you though as it is not recommended by Jtec. I've done that on several new mufflers and when removed for maintenance, the mating surfaces look perfect. Unsupported, the engine side always looks perfect, the muffler side shows the wear after some time in use. Adding the harder flange material stops the whole process. I added a thinner, hard shim once and it didn't work out well.

I hate to even mention something like this in a forum as it casts a bad light on the mfgr, Jtec in this case. That is not my intention in any way. They are great people and they make a great product. They've done custom jobs for me several times now and I'm sure I'll be calling on them once again.