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Thread: Broken exhaust support

  1. #1
    conch
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    Broken exhaust support

    My PA 18 has a performance (Hot Rod Muffler) that uses a strut that runs from the exhaust to the exhaust manifold on the right side of the engine which keeps breaking. Has anyone had this problem and does anyone know the cause or solution.

    thanks, Conch

  2. #2
    Darrel Starr's Avatar
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    Is the muffler or tail pipe vibrating against the firewall or some other airframe part?

  3. #3
    Aviator's Avatar
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    Sounds like the vibrating mass of the muffler might be too much for the strut the way it's aligned. Had a similar problem with a C-180 airbox that kept cracking around the carb flange. A short 3/8” strut tubing fixed that problem once and for all.

  4. #4
    skywagon8a's Avatar
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    The clamp at the tail pipe end is TOO tight. Stainless Steel is prone to cracking when it is stressed, heated and vibrated. The brace does not get heated as much as the exhaust, so the relationship between the two changes, causing increased stress on the connection. The smaller part will crack. Loosen the clamp that holds the brace to the tail pipe enough so that it will slide a little bit. This will compensate for the increased stresses. Sometimes a spring, incorporated in the connection at one end of the brace, is used. Also make sure that the brace does not touch any thing else as that can also cause stresses in the parts. Remember that the engine is moving all the time. A part may clear when it is not running, but may be hitting something while you are flying causing stresses.

    The exhaust system DOES need that brace. If the brace is not installed the exhaust pipe or muffler will crack. Most likely near a welded joint. You don't want that $$$$$$$.

    Look under your car. Isn't the end of the tail pipe supported by a flexible connection? That is why.
    Last edited by skywagon8a; 10-14-2013 at 05:16 AM.
    N1PA

  5. #5
    conch
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    No, it is clear all around.

  6. #6
    sjohnson's Avatar
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    In my case, the clamp that attaches the strut to the exhaust riser has broken twice.

    - Has anyone else experience this?
    - What is the replacement PN?

    Help.

    Update: I got a nearly immediate response from Atlee Dodge:
    - consider putting rubber between the support rod and the clamp
    - they're sending a clamp in the mail.

    Great service !
    Last edited by sjohnson; 07-25-2014 at 02:49 PM.

  7. #7

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    I had my clamp brake, I was in town and stopped by the shop. Steve gave me a new clamp and told me to make sure that everything was lined up with no stress on the rod or clamp. he also talked about the rubber trick if it happened again. Great support as always. I know of one other one that had a clamp brake. I feel a lot more vibration at 2100-2300 with this muffler, I think the baffling in the stock one helps reduce the harmonic vibration from the exhaust pulse (that is a lot of big words, I think I got them right). Anytime you change from stock it will effect something else sometimes good sometimes bad.
    DENNY

  8. #8
    pa11driver's Avatar
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    I had the same thing with mine, it broke twice in 35 hours. I used the rubber pieces Steve at Atlee gave me and have had no trouble with it since.

  9. #9
    55-PA18A's Avatar
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    Could you describe these rubber pieces, or maybe take a photo?

    Jim W

  10. #10
    pa11driver's Avatar
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    I believe what Steve gave me is just the piece of rubber used in a cessna tail pipe shock mount assembly.

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