Exhaust Clamp Bolt Broken

Eco Mouse · 05-12-2016, 11:18 PM

The bolt that tightens down the muffler to the header pipe just broke right in half.

So the other day, the woman comes in and says she thinks the muffler seems a bit wobbly. I dismissed it as, all mufflers kinda wobble, especially on a thumper.

Well, I decided to go check, sure enough, it's a wobblin'. But the cause was not what I thought. Here I was thinking hanger bolts. Nope, it was loose at the flange where it slips on over the header pipe. OK, no big deal, I'll just grab a 10mm socket and tighten it back down... SNAP! The stainless steel bolt just snapped in half as I was applying pressure. Now I was only using 1/4" drive, and I'm still recovering from carpel tunnel, so there was no way I was wrenching on it that hard.

Anyway, just thought I'd let you guys know to check that bolt from time to time. I'm pretty sure the heat cycles have tempered the stainless bolt to a brittle state.

SpudRider · 05-13-2016, 12:23 AM

Thanks for posting the warning.

Jay In Milpitas · 05-13-2016, 11:09 PM

Pictures of the bolt?

dpl096 · 05-13-2016, 11:24 PM

Yes.., ditto Spud - thank u

Eco Mouse · 05-13-2016, 11:31 PM

Sorry, I chucked the bolt... but it's right above your right side foot peg. Can't miss it. It's a fancy hose clamp looking thing.

The bolt head is 10mm, and the thread is 6mm at a 1.0mm pitch. I couldn't find an 8.8 grade replacement bolt that had long enough threads, so I ended up getting a cap screw and a pan head. Both with hex-key/allen holes.

Something that I did notice, is that the barrel that the bolt threads into on the other half of the clamp, is also stainless. And the threads were really galled up. Stainless has a habit of doing that. So... if you guys go to check that bolt, and can get it off without twisting it in half, I suggest you dip that bolt in some Milk of Magnesia before threading it back on. That will keep the threads from galling. Or, you can use a different type of steel bolt, and not a stainless one. Which is what I did.

detours · 05-13-2016, 11:37 PM

Thanks for the heads up on that bolt!

Jay In Milpitas · 05-14-2016, 12:06 AM

Quote:

Originally Posted by Eco Mouse

Sorry, I chucked the bolt... but it's right above your right side foot peg. Can't miss it. It's a fancy hose clamp looking thing.

Thanks, I understood the location. Was hoping to see if the bolt displayed signs of distress.

zingshoen · 05-14-2016, 12:25 AM

chinese steel? "steel"?

RedHawk47 · 05-14-2016, 01:44 AM

Quote:

Originally Posted by zingshoen

chinese steel? "steel"?

The problem is not (Chinese) steel, but as Eco Mouse explained, the choice of a SS bolt in a SS "nut".
1. SS in SS will gall and seize, resulting in the bolt "twisting off".
2. The yield strength of SS bolts is 60% of a Grade 2 bolt - my local hardware store doesn't even sell Grade 2 bolts because they are so inferior. A Grade 5 bolt has 160% the strength of a Grade 2, and 260% the strength of a SS bolt.

05-12-2016, 11:18 PM	#1
Eco Mouse Join Date: Jun 2015 Location: Las Vegas Posts: 158	Exhaust Clamp Bolt Broken The bolt that tightens down the muffler to the header pipe just broke right in half. So the other day, the woman comes in and says she thinks the muffler seems a bit wobbly. I dismissed it as, all mufflers kinda wobble, especially on a thumper. Well, I decided to go check, sure enough, it's a wobblin'. But the cause was not what I thought. Here I was thinking hanger bolts. Nope, it was loose at the flange where it slips on over the header pipe. OK, no big deal, I'll just grab a 10mm socket and tighten it back down... SNAP! The stainless steel bolt just snapped in half as I was applying pressure. Now I was only using 1/4" drive, and I'm still recovering from carpel tunnel, so there was no way I was wrenching on it that hard. Anyway, just thought I'd let you guys know to check that bolt from time to time. I'm pretty sure the heat cycles have tempered the stainless bolt to a brittle state.
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05-13-2016, 12:23 AM	#2
SpudRider Join Date: Jul 2008 Location: Idaho Posts: 25,054	Thanks for posting the warning. __________________ Spud "Never argue with an idiot. He will drag you down to his level, and beat you with experience." Mark Twain 2015 Zongshen ZS250GY-3 (RX3) 2006 Zongshen ZS200GY-2 (Sierra 200) 2005 Honda XR650L 2004 Honda CRF250X 1998 Kawasaki KDX220 Mods made to my Zongshen ZS200GY-2: http://www.chinariders.net/showthread.php?t=6894
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05-13-2016, 11:24 PM	#4
dpl096 Join Date: Sep 2015 Location: East Central Hellinois Posts: 1,344	Warning Yes.., ditto Spud - thank u __________________ ************************************************ * " Time you enjoy wasting, is not wasted." - John Lennon “I predict future happiness for Americans, if they can prevent the government from wasting the labors of the people under the pretense of taking care of them.” ― Thomas Jefferson "If you don't know where you're going any road will take you there" ....George Harrison song
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05-13-2016, 11:37 PM	#6
detours Join Date: Sep 2014 Location: Arvada, CO Posts: 1,004	Thanks for the heads up on that bolt! __________________ Red 5 standing by! 2015 CSC red RX3 with 19" front wheel, Shinko 804/805, skid plate, tall seat, 13T/45T sprockets, progressive shock, Winyoochanok windshield, GENSSI LED headlight, SW-Motech tankbag, Shorai Lithium battery 2014 Ural Patrol
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05-14-2016, 12:25 AM	#8
zingshoen Join Date: Jun 2009 Location: Brisbane, Queensland, Australia Posts: 648	chinese steel? "steel"? __________________ 1971 Garelli Gulp 50cc with open ports and 16 mm Bing Carbie + 1980 Honda XL 223 ZS + 2007 Zongshen LZX200G + DR400SM
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05-13-2016, 11:09 PM	#3
Jay In Milpitas Join Date: Jul 2015 Location: Milpitas, CA. USA Posts: 775	Pictures of the bolt?
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05-13-2016, 11:31 PM	#5
Eco Mouse Join Date: Jun 2015 Location: Las Vegas Posts: 158	Sorry, I chucked the bolt... but it's right above your right side foot peg. Can't miss it. It's a fancy hose clamp looking thing. The bolt head is 10mm, and the thread is 6mm at a 1.0mm pitch. I couldn't find an 8.8 grade replacement bolt that had long enough threads, so I ended up getting a cap screw and a pan head. Both with hex-key/allen holes. Something that I did notice, is that the barrel that the bolt threads into on the other half of the clamp, is also stainless. And the threads were really galled up. Stainless has a habit of doing that. So... if you guys go to check that bolt, and can get it off without twisting it in half, I suggest you dip that bolt in some Milk of Magnesia before threading it back on. That will keep the threads from galling. Or, you can use a different type of steel bolt, and not a stainless one. Which is what I did.
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