twolter

Hi Guys,

Well I did it. I finally flew my brand new Hangar9 p-51 Mustang today and you know, I just can't wipe this stupid smile off my face !!! This plane flew so well - It was fantastic !!!

Only problem was that the end half of the muffler would rotate loose during each flight. No matter how tight I screwed that nut on the threaded rod that goes up the middle of the muffler, it still worked loose. I even put loctite on the nut but it didn't work.

I was going to put a set screw through the two halves tonight but the inside lip does not overlap enough on the inside to get a screw in there.

Any hints guys ?

Cheers,

Troy

rwright142

How about double nutting (adding a second nut behind the first one)?

da Rock

The rod should be tightened first. If it's not tight, the lock nut hasn't got a chance.
If there's room, a star washer helps. But only if the bolt is tight first.

And......
Clean it up squeeky clean and JB Weld the seam that slips.
or
Put it in the freezer overnight and tighten everything up while it's dead cold.
or
Use valve grinding compound to get a perfect seam. That'll take away any play that winds up giving the bolt room to loosen.

Steve Collins

My Feedback: (8)

JB Weld seems to work best everytime. Just make sure the surfaces to be glued together are very clean before using the JB Weld.

Deadeye

Tighten cold? I thought tightening while hot was the ticket?

Birman

Do what the Saito guys do. Put two turns of teflon plumbers tape on the threads.

Scar

My Feedback: (3)

I'd loosen up the lock nut, tighten the screw with everything cold, and then tighten the lock nut. The threads are in the exhaust exit housing.

If you tighten the screw when the housings are hot, they shrink later, relaxing the load on the screw somewhat. If you tighten the screw with the housings cold, the screw can handle the increased axial load when the housings expand with heat.

Good luck,
Dave Olson

pilot727

I have your answer, i take most of my mufflers when i have trouble and i put a threaded rod through it with lock tight lock nuts on each end and you will never have a problem again and you do not need to use but a drop of lock tight, problem solved if we are talking about the same thing, good luck

pilot727

Another thing is that all phillip screw's in a kit when i open the kit i throw all of them screw's right into the garbage and i replace them with all allen head bolts when i can, i do not know why they use allen head screw's when they all strip everytime you try and take them out or put them back in, try it and you will stop so many problems and when you need to take the bolt out, it will come out even if it is lock tight in, i even use a metric allen head bolt on all of my servo screw's, the right size will fit tight just get the right length so it does not touch the pot gears and make it go hay wire

da Rock

Put the muffler parts into the freezer. They'll contract to a shorter length.

Leave the bolt and nut out of the freezer. It will not shorten.

Pull the shortened muffler out of the freezer in the morning and run the bolt through and TIGHTEN IT in the threaded muffler. Then run the nut on and tighten.

When the muffler warms up, it'll try to lengthen and simply tighthen everything even more. And when the motor is run............

pilot727

Thank you, i never heard of that one but i am here to learn from people like yourself and i myself have learned so much from different people here, and such nice people, we all sometimes say things we do not mean but i try and listen to everyones point of view, thanks

jetmech05

J B Weld seems permanent....why not use high temp silcon (RTV) the red stuff on the two halves of the muffler. the best thread locker i've seen is gel super glue and its not permanent.

pilot727

A threaded rod with a nylon nut on each end not only looks good but is cheap and comes off and on anytime very easy, we all do it this way here but it is your plane to do as you want to do, weld it if you want to that would work also

twolter

Hi Guys,

Thank you all for your help with this issue ... It's great the way everyone takes the time to provide information on these forums. Can't wait to get home tonight to get working on my plane.

Cheers

Troy