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JohnF
Joined: 13 May 2010
Posts: 124
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 Posted: Wed Aug 25, 2010 7:10 pm Post subject: Bad Bolt |
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Here is a bolt from the gear box of a 912ULS...factory new engine. Bolt was removed for box inspection and never re-installed. Looks like severe over torque or bad manufacturing, but Rotax could not have properly torqued the bolt because when I tried it the bolt would go in a certain distance and then just spin without ever tightening.[img]cid:EADEEEE63413438FAA2D41165432DCB2(at)John320gbPC[/img]
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daberti(at)sbcglobal.net
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| Posted: Wed Aug 25, 2010 7:52 pm Post subject: Bad Bolt |
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Are you sure that it did not get that way when it was removed. Did you check the installed thread engagement length against where the distortion occurred?
[quote]
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Thu Aug 26, 2010 4:37 am Post subject: Bad Bolt |
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Spins without ever tightening? Sounds like stripped threads, which would be the other symptom of this having been put in and over torqued. What happened when you put in a new bolt? Did it spin, too?
Rick Girard
On Wed, Aug 25, 2010 at 10:51 PM, Dave <daberti(at)sbcglobal.net (daberti(at)sbcglobal.net)> wrote:
[quote] Are you sure that it did not get that way when it was removed. Did you check the installed thread engagement length against where the distortion occurred?
[quote]
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flyadive(at)gmail.com
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| Posted: Thu Aug 26, 2010 4:43 am Post subject: Bad Bolt |
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John:
This is real crazy and not in a good way.
The bolt - Allen Head Cap Screw - looks like it is plated. Either Nickel or Chrome. And in my plating days I have seen the same mis-shaped threads
Happen because of poor electrical contact where the wire was attached to the screw.
Notice the shape of the threads in the reduced area. They profile the original. right down to the crown. Just that the MAX Diameter is not correct.
This can happen during plating, since in the cleaning process they use reverse current. Add that to a poor wire contact and that is what you will see.
NEXT - Possibility - I can not tell from the picture very well, but, measure the distance over the thread crests. See if they get wider.
This would be a good indication that the screw was over torqued and stretched.
Barry
On Wed, Aug 25, 2010 at 11:08 PM, John Fasching <n29cx(at)ridgeviewtel.us (n29cx(at)ridgeviewtel.us)> wrote:
| Quote: | Here is a bolt from the gear box of a 912ULS...factory new engine. Bolt was removed for box inspection and never re-installed.
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| Quote: | Looks like severe over torque or bad manufacturing, but Rotax could not have properly torqued the bolt because when I tried it the bolt would go in a
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| Quote: | certain distance and then just spin without ever tightening.[img]cid:EADEEEE63413438FAA2D41165432DCB2(at)John320gbPC[/img]
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JohnF
Joined: 13 May 2010
Posts: 124
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| Posted: Thu Aug 26, 2010 9:58 am Post subject: Bad Bolt |
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No, a replacement bolt went in and torqued up properly...I don't understand it either, but it seems OK now....just some weird thing I though folks might be interested in and perhaps know the reason...it came out readily without any excessive force - same as its mate on the other side of the gear box.
JohnF
[quote] ---
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s.clive.richards(at)homec
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| Posted: Thu Aug 26, 2010 12:34 pm Post subject: Bad Bolt |
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Hi All
If you reply to a post such as this please remove the large picture & large amounts of text from original attached post as Mats guide lines, I thought I was still on dial up after 4 copies, some of us can only get snail band 0.5 meg or less.
John
Is the eroded part of the bolt at a place where two parts join or is in a place open to internals of gear box ? if so could be caused by corrosion.
You say it only went in part way & spun so the threads down to this point must be stripped, did the protruding part have sufficient length left that sufficient thread are left for new bolt to hold safely?.
Clive
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flyadive(at)gmail.com
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| Posted: Thu Aug 26, 2010 1:38 pm Post subject: Bad Bolt |
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GOOD POINT Clive.
ALSO Gaggle.. I have noticed there becomes a few responses that are NOT attached to the original post. Keeping a thread can become a bit garbled when responses are NOT done on the SAME post.
Just good educate... Not that I'm PC or anything like that.
Barry
On Thu, Aug 26, 2010 at 4:32 PM, Clive Richards <s.clive.richards(at)homecall.co.uk (s.clive.richards(at)homecall.co.uk)> wrote:
[quote] Hi All
If you reply to a post such as this please remove the large picture & large amounts of text from original attached post as Mats guide lines, I thought I was still on dial up after 4 copies, some of us can only get snail band 0.5 meg or less.
John
Is the eroded part of the bolt at a place where two parts join or is in a place open to internals of gear box ? if so could be caused by corrosion.
You say it only went in part way & spun so the threads down to this point must be stripped, did the protruding part have sufficient length left that sufficient thread are left for new bolt to hold safely?.
Clive
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Roger Lee
Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.
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| Posted: Thu Aug 26, 2010 2:35 pm Post subject: Re: Bad Bolt |
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Hi Guys,
I agree about replying to post. Use the "reply" tab at the top or bottom of the page. Don't use the quote tab. Some of these post are terribly long to scroll through to read the other persons answer.
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