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Posted On: 4 Hours Ago
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13th June 2014
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Biker
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Join Date: Jun 2009
Posts: 55 Sportster/Buell Model: Buell X1 Lightning Sportster/Buell Year: 1999
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rocker box bolt keeps snapping
I installed Buell XB rocker boxes on my Buell X1 a few years back and when i did the rear cylinder rear 1/4-20 grade 8 HD hex bolt snapped/sheered off on me. I have had my rockers off all winter and machined a drill guide and drilled this bolt out, and put a helicoil in the head. So i am installing the rocker boxes last night and torquing the bolts to spec and in the same location, the bolt snaps again!!! Im torquing them to what my service manual calls out - 10-14 ft/lbs. Pulled it all apart and lucky the way the bolt snapped I was able to just spin it out with pliers. Its a 1/4-20 grade 8 HD bolt and it snaps at 10 ft/lbs of tq, what gives?
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13th June 2014
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Senior Chief Master Mechanic
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Join Date: Aug 2007
Location: Flori-duh
Posts: 957 Sportster/Buell Model: XL1200C/1250 Sportster/Buell Year: 04
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Just some thoughts/questions.
Are you sure the wrench is in calibration?
Torque wrenches are inherently not real accurate at the bottom or top of their range. For accuracy, you want to work in the middle of the wrenches range, not at either end.
For 10-12 ft/lbs, the better wrench choice might be something like a 20-250 IN/lbs wrench, torquing at 120-144 IN/lbs.
Are you using any extensions on the wrench and not recalculating for the extension factor?
__________________
Hammer 1250-Smash Heads-560 Cams -Hurricane Flow AC -Supertrapp Supermeg -TC88A
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13th June 2014
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Senior Custom Bike Builder
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Join Date: May 2011
Location: spencerville
Posts: 2,611 Sportster/Buell Model: sportster Sportster/Buell Year: 2003 Sportster/Buell Model #2: 1200 xl sportster custom Sportster/Buell Year #2: 03 Other Motorcycle Model: 1200 low sportster Other Motorcycle Year: 06
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better yet are you bottoming out the bolt g8 bolts are pretty taught . as stated above good tq wrench are a must.
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13th June 2014
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A Million Facts & Figures
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Join Date: Jan 2005
Location: Famous Potatoes
Posts: 10,247 Sportster/Buell Model: XL883 Sportster/Buell Year: 2007 Sportster/Buell Model #2: Buell Cyclone Sportster/Buell Year #2: 1999
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ft-lb torque wrenches aren't real accurate that far down the scale.
I use an in-lbs torque wrench and torque to 150 and they don't break.
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1st August 2014
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Greasemonkey
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Join Date: Aug 2014
Posts: 120 Sportster/Buell Model: XL883 Sportster/Buell Year: 2003
Reputation: 10

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The same happened to me on my front rocker box. I agree with the idea that torque wrenches suck at those low torque specs. My wrench clicked over fine on the rest of them but the very last one snapped off.
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1st August 2014
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Brass Nut
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Join Date: Feb 2005
Location: Western Weald
Posts: 46,900 Sportster/Buell Model: XL1200CB Sportster/Buell Year: 2015 Other Motorcycle Model: CRF250L Other Motorcycle Year: 2017
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Torque wrenches are accurate at the top of the range, but not at the bottom.
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Folkie
Super Moderator
South East England Riders
There is nothing at the end of any road better than may be found beside it. Edward Thomas (1878 - 1917)
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1st August 2014
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XL FORUM TEAM MEMBER
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Join Date: Jun 2011
Location: On a farm
Posts: 6,395 Sportster/Buell Model: XL77.2R Sportster/Buell Year: 2006
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I use a cheap beam type torque wrench ; never break bolt.
I love those clicker, I make money welding holes busted being over torque by clicker.
Keep clicking so we the machine shops and welders make money with your mistakes.
A 19.00$ sears beam type 3/8 is perfect for that job.
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