New Sissy Bar from Choppin Steel

Energy One
G

Gas Man

Cool isn't cheap
Calendar Participant
Jazzy said:
Yep, I think the bolts were the problem after all. Had the thought to go get grade 8 bolts, but didn't follow up. Just used the stainless ones I had in the garage.

Airbrush-ed, thanks for the PM. I'll send you some pic's of the rear fender tomorrow.
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Next time get chromed grade 8s. They carry a 8.8 grade.
 
Byrddogg

Byrddogg

Active Member
I've had my 18' sissy bar on my bike ever since I bought it in 07, only using the bolts that came with it. Never had them back out or anything, no loctite. Maybe I'm just lucky?
 
PROFLYER

PROFLYER

SWOLE
FYI, I had one of my bolts shear off on my old sissy bar. Big Dog recalled all the sissy bars that were under a certain circumference because the didn't fit tight enough in the holes which caused vibrations and the bolts to shear. I bet you money your bolts sheared off.
 
4thHorsemen

4thHorsemen

Member
Jazz, sorry to hear this man. That sissy bar matchin your paint was sick. Glad you're gettin another one (whenever that be). Like to see it person. I did learn where to go for chrome plating from your thread.
 
Slick-Dog

Slick-Dog

Active Member
Nice!!! just dont trip up around that:) ... use it as a weapon to....hiiiiyaaa :nopity: all joking aside...its bad ass!
 
bigdog1rm

bigdog1rm

Member
About a year ago i too had my second sissy bar custom made fall off and tear up my struts and luckly not my fender.Also used grade 8 bolts from Fastenal that broke off flush with the bottom of sissy bar and were RED locktited.I was told that the sissy bar was too heavy and probably the only bolts that will be strong enough would be air craft titanium allen head bolts but would have to be threaded down because they have a short threaded area,does anybody know about this being true and where to locate these bolts.Sorry that you have not been able to locate your sissy bar,that sucks.
 
R

Rocco216

New Member
Can anyone tell me the link to coppin steel, I am looking to have a custom sissy bar made for my 2005 mastiff,thx
 
M

MichiganPitbull

New Member
Jazz...sorry to read further into the thread and see that you lost it. That sucks! I'm betting shear at the threads. Metal fatigue/stress is induced into the metal when threads are cut. It's often a point where shear occurs. You may have done everything right but the threads may have held the problem. I'm curious if they did any heat treating/stress relief in this area or just chromed mild grade metal plate after water cutting???

Cycle fatigue 101... Low hardness/non-heat treated metal can only flex so many times before it will crack and shear at the point of highest stress (probably at the threads). If this was untreated plate/metal, I can guarantee that it cycled 80,000 times (or more) and then sheared at the threads. That seems like a big number until you realize that you could cycle 10,000 times during a tank of gas (depending on the mounting/resonance of the part and how it mates with what looks like factory struts). Given the metal grade and the part resonant frequency, I could actually run a calculation for how long before the metal vibrated itself to death and sheared off. Years of Mechanical Engineering classes have only made me good for annoying people, chasing women off and calculating stress and fatigue. haha! Boring chit...but my point is that you can do everything right and if the part design has issues, they will become evident. Seems to me the part didn't pass your validation testing. Beware of part two if you or others misdiagnose the failure mode.

I'd bet money that the Big Dog factory Sissy Bars were heat treated and then possibly stress relieved at the threads. Makes chit expensive...but necessary! Imagine if your girl was leaning back against the bar. Ooof.
 
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