raron455

My Feedback: (38)

OK, fellas I need some more advise, Ihave a pitts style muffler on my dle-55. the muffler keeps coming loose, the bolts are backing out,,Icleaned the head and mufffler then put a thin coat of high-temp rtv, then cleaned the bolts and put some red loctite on them, put them in the engine, and tightened them, they got tight, and let it sit for a whole day,, I flew about 4 times and the muffler is loose again,, is there something I dont kow about, or that Iam missing??

All Day Dan

My Feedback: (5)

Try lock washers instead of the Loctite. They always work for me. The DLE threads are probably metric. Make sure your screws are metric. Dan.

raptureboy

You could also drill the heads of the bolts and run some safety wire just like real airplanes.

flyinwalenda

My Feedback: (5)

Safety  wire them   If they are cap head bolts you can drill a hole through the sidewall of each and then string some thin music wire through them in a figure-8 pattern and tie/twist it off. .

kmeyers

I use High temp RTV as a threadlocker on my muffler bolts.

Is there a strap on the far backside of the muffler that supports to one of the engine mount lugs and prevents vibration?

If not, you need to fabricate one and that will stop your problem.

karolh

Most all Pitts style mufflers need an additional strap/mount to reduce vibrations from the engine which is what loosens the muffler bolts.

Karol

CK1

My Feedback: (60)

If you are getting excessive vibrations from the prop or spinner it will be difficult to keep the muffler tight . If the bolts are getting loose even though ou have cleaned and applied loc-tite I suspect you have a vibration concern.

raron455

My Feedback: (38)

Cant safety wire them because they are deep in the muffler,,
NO there is not any kind of brace, just the two bolts holding it on the engine,,SO I should just fab up some kind of L-bracket or something, that bolts the muffler to the firewall?? once I have it on and tight?

raron455

My Feedback: (38)

Thanks Fellas,, I think I figured it out,, never knew you had to have  a bracket on this style muffler,, I just read this article and I am going to make a bracket,, Appreciate the help guys

Like this
http://www.troybuiltmodels.com/ns/in..._bracket.shtml

All Day Dan

My Feedback: (5)

raron, Check the muffler mounting threads in the cylinder. It's pretty easy to damage them when the muffler gets loose. Dan.

speedracerntrixie

My Feedback: (29)

Keep an eye on your temp as well. I agree that you need the strap but running the engine too hot will contribute to this issue too.

daveopam

My Feedback: (9)

Also, don't attach the support strap to the fire wall. It needs to move with the engine.

David

raron455

My Feedback: (38)

OK fellas when I ask for advise I always listen, thanks for the help , here is what I did, Of course I already mounted it to the firewallbefore reading the last post saying to mount it to the engine,, Makes sense, I am gonna give this a try though, seing how I drilled two holes in my plane,, Ihave done alot of research and most people are mounting their brace on the firewall, even on troybuilts site they show it being mounted to the firewall, if I have any problems then I am going to do what daveopam suggest and try to mount it to the engine,, we will see how this works out.

unclecrash

I had the same problem on a huskvarna chain saw. Once they backed out it was over. They wallow out the threads and will not stay. I had it in the shop 3 times because it was under warranty. I wound up getting a new saw. A friend and I use permatex rtv copper plus as the gasket and as a thread locker and it works great. My friend has a lot of big gasser's and never has had one come loose.

john josey

The mounting strap and "nord lock" washers should provide a complete cure.

daveopam

My Feedback: (9)

You did a great job!! I would try it as is. If there is not a lot of flex in your stand offs it should work fine.

David

unclecrash

As long as the hole's are not wallowed out.

raron455

My Feedback: (38)

Well, so far everything is still tight and good,, 8 flights so far with bracket,, before bracket 2nd flight and muffler was loose,, thanks for all the help fellas, I appreciate it.
Ronnie

dasintex

My Feedback: (10)

To mount the strap to the Muffler, did you Drill and Tap thread the mounting holes for the thread of the srews you used, or, did you use self tapping screws? also, what did you use, if any, to stop those Screws securing the bracket to the Muffler from vibrating loose?

raron455

My Feedback: (38)

I made the bracket, mounted it to the firewall using 6-32 bolts with locknuts, I drilled and tapped the bracket and muffler together, that way the threads would have more bite, and less chance of coming loose, I put them in with red loctite.

vertical grimmace

My Feedback: (1)

Generally, muffler contact with airframe is a bad idea. Sorry, it may be working, but it might be wise to get that strap mounted back to the engine itself and not the airframe. Your setup is going to transfer loads to the muffler and could result in a crack.
Anyone remember why you never want mufflers contacting the airframe? Just sayin'

All Day Dan

My Feedback: (5)

Vertical, you never connect the muffler to the airframe because it does not vibrate at the same rate, with the same displacement and at the same phase as the engine. In other words the assembly is under stress at all times. However, it does work sometimes. Dan.

vertical grimmace

My Feedback: (1)

So, this would be one of those times? Time will tell.

dasintex

My Feedback: (10)

It's pretty simple why you don't attach the Support Strap to the Airframe, you want the Muffler to vibrate/flex with the engine, if it's attached to the frame or firewall, it won't vibrate or flex with the engine as it moves, as solid as the engine feels mounted on the standoffs, the engines will still move, firewalls typically flex a bit, I plan on making a support strap for my wrap around pitts on a Warbird, I will attach it to the end plate of the Muffler and the other end will be secured under the Engine Mounting Bolt and standoff, any thoughts on this set up?

djstar39

My Feedback: (4)

The Troybuilt link above says All Pitts mufflers (except Jtec)... I have a Jtec Pitts muffler for my DLE-20 that I'm getting ready to install. Do I need to strap it?

Dave