X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-pz0-f52.google.com ([209.85.210.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.5) with ESMTPS id 5578908 for flyrotary@lancaironline.net; Mon, 04 Jun 2012 16:02:50 -0400 Received-SPF: none receiver=logan.com; client-ip=209.85.210.52; envelope-from=crobinson@medialantern.com Received: by dano14 with SMTP id o14so6050111dan.25 for ; Mon, 04 Jun 2012 13:02:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:x-gm-message-state; bh=yvtV6+q2TjspNHeV8jni3oBa+Ip01EplPBlaQYD4KZg=; b=SkL/IkI8k2KUV8DdGxMCoR/wvtU6bSNAMnJB5hWTUuWhz+8YNNv9gk4BTlBFKcWTck Ez/u7eMcyqKgPbnX6skgX9gzBFQwHmXmMzxDS7Nzmk0lNrOQlf/8KWPpw3+2gapmwbD9 /E5uCWOKNWT26geU09uSGj8ucS567B3S2GOMCF00Ej9Y5jFqQsEPh3e6NyPFz5OYjDRy 1PH4/j9yTmsPx3TK6RVWxEox4XlcYvTb/LYtU4JKWoD2D/aG8upfDeAExMx7RmZUmP9w 4oBxoxv/M10xILVxHsG4ytytQ1MnVaTOm7VqoLGFfBrZ5tnpnc86N4SSz4cr5i0kKL53 5mcA== Received: by 10.68.237.166 with SMTP id vd6mr41855635pbc.139.1338840135065; Mon, 04 Jun 2012 13:02:15 -0700 (PDT) Return-Path: Received: from MAC_MBP110886.local (L3-NM-254.wwe.com. [63.208.148.254]) by mx.google.com with ESMTPS id ok6sm14307538pbb.29.2012.06.04.13.02.12 (version=SSLv3 cipher=OTHER); Mon, 04 Jun 2012 13:02:13 -0700 (PDT) Message-ID: <4FCD1442.7080307@medialantern.com> Date: Mon, 04 Jun 2012 16:02:10 -0400 From: Chad Robinson User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Rotary motors in aircraft CC: DLOMHEIM@aol.com Subject: Re: [FlyRotary] Exhaust Bolts Question References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------010400010805090509080603" X-Gm-Message-State: ALoCoQmysKneK5I2pe2Xjqpy5oM2fappj0AlXC6s1A3vE7zN4fss4X1REVajCEIkAkyABah1T9hb This is a multi-part message in MIME format. --------------010400010805090509080603 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit I was curious about the same thing so I researched studs specifically and it turns out to be a pretty simple answer. When you turn the head of a bolt it needs to resist tension AND twisting. Studs only need to resist tension - you turn only the nut, and the stud doesn't get twisted while you tighten it. They can make the stud a lot stronger in tension than a similar bolt. That's an advantage when you're attaching something heavy in a high-vibration area (like an exhaust header). If you're worried about safetying them and you can't get them safety-wired, just use a thin strap of steel, one across the top and one across the bottom, with a hole drilled for each bolt/stud. That acts as a washer under the heads of the nuts. Once you get it all tightened down just stake/bend one edge up flush with the side of the nut so it can't turn. Mazda uses the same technique for a few nuts inside the engine. On 6/3/12 11:56 PM, DLOMHEIM@aol.com wrote: > As you all can see in my previous exhaust picture, my 13B has bolts to > hold the exhaust manifold on (which is the way that Tommy James flew > it in his Glastar for 50 hrs. or so) before I bought it. I am > thinking that I should probably swap out these bolts for studs and > nuts, since I don't ever want have to worry about bottoming the bolt > out and then stripping out the treads when torqueing them per spec., etc. > So my question is what are most of you all flying with...studs or bolts? > Also, if I add studs, is there a product anyone can recommend (such as > a loc tite type product) that will help keep the stud from backing out > but also survive in the high temp environment by the exhaust > manifold? Is the RED Loctite made for this type of duty factor? > Thanks for any information. > Doug --------------010400010805090509080603 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit I was curious about the same thing so I researched studs specifically and it turns out to be a pretty simple answer. When you turn the head of a bolt it needs to resist tension AND twisting. Studs only need to resist tension - you turn only the nut, and the stud doesn't get twisted while you tighten it. They can make the stud a lot stronger in tension than a similar bolt. That's an advantage when you're attaching something heavy in a high-vibration area (like an exhaust header).

If you're worried about safetying them and you can't get them safety-wired, just use a thin strap of steel, one across the top and one across the bottom, with a hole drilled for each bolt/stud. That acts as a washer under the heads of the nuts. Once you get it all tightened down just stake/bend one edge up flush with the side of the nut so it can't turn. Mazda uses the same technique for a few nuts inside the engine.

On 6/3/12 11:56 PM, DLOMHEIM@aol.com wrote:
As you all can see in my previous exhaust picture, my 13B has bolts to hold the exhaust manifold on (which is the way that Tommy James flew it in his Glastar for 50 hrs. or so) before I bought it.  I am thinking that I should probably swap out these bolts for studs and nuts, since I don't ever want have to worry about bottoming the bolt out and then stripping out the treads when torqueing them per spec., etc.   
 
So my question is what are most of you all flying with...studs or bolts?
 
Also, if I add studs, is there a product anyone can recommend (such as a loc tite type product) that will help keep the stud from backing out but also survive in the high temp environment by the exhaust manifold?  Is the RED Loctite made for this type of duty factor?
 
Thanks for any information.
 
Doug

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