Author Topic: Broken footpeg - anyone else?  (Read 1889 times)

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Offline japes1275

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Re: Broken footpeg - anyone else?
Reply #10 on: May 24, 2020, 11:33:30 AM
Iíd say itís a combination of the footrest lowering block and the unconventional way you get it off the stand.

Iím no stress engineer but I think the way the lowering block attaches the footrest  (and Timorís thread contact reasoning) puts more stress on the casting. Couple that with repeated application of weight from standing and rocking and you can see the result.

Iím not sure that rocking the bike off the stand whilst on it is a good idea to be honest. If you look at the centre stand mounting point you will see that it isnít the strongest of things and rocking with another 150kgs on the bike is putting a lot of load through it.

Offline japes1275

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Re: Broken footpeg - anyone else?
Reply #11 on: May 24, 2020, 11:36:37 AM
Sorry, just had a look at the photo again and can see that the lowering block canít really affect the stress on the actual broken part - probably more stress on the footrest hanger though.

Offline Perfictsib

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Re: Broken footpeg - anyone else?
Reply #12 on: May 24, 2020, 12:28:23 PM
another factor could also be there is no large washer between the footrest and nut to spread the weight going through the footrest, look at the footrest hanger lower pivot support its a lot wider than the nut.

I would even fit a spacer where the old footrest spring used to be for a bit more strength
Last Edit: May 24, 2020, 12:33:12 PM by Perfictsib

Offline CB-500-X

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Re: Broken footpeg - anyone else?
Reply #13 on: May 24, 2020, 01:58:00 PM
Looks like a motowerks peg lowering kit.

Offline Oyley

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Re: Broken footpeg - anyone else?
Reply #14 on: May 24, 2020, 02:15:17 PM
I'm with Timor on the bolt theory.
I feel the bolt should not have the threads in contact with the foot peg as those steel thread high points are likely to be cutting into aluminium with the varying loads on the pegs.
Plus if you fold the pegs back with your leg when reaching for the sidestand like most do, you could be adding a rotational force with the steel threads within the aluminum.
On top of that, the way you jump of the stand to set off adds weight to your pegs.
I suspect it's a combination of the above.
Did your kit for lowering your pegs come with that bolt?
I would have expected to come with a longer shoulder of unthreaded area, you dont tend to see threads on areas that have ongoing rotational forces.
Examples on your bike will be clutch, brake levers, they are always in my experience unthreaded pivot pins or bolts...just like the original on your foot pegs.

Offline Oldsolum

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Re: Broken footpeg - anyone else?
Reply #15 on: May 24, 2020, 02:27:09 PM
Thanks all - I knew I'd get good advice from you folks. I have a Motowerk footpeg lowering kit and I used all the hardware that came with it, including that bolt whose unthreaded collar is now know to be too short. No, I didn't drill anything to make it fit. FWIW, I installed the Motowerk kit 3 years and 55,000 miles ago. I'll try to find a new bolt with a longer unthreaded collar when I install the new footpegs. Thanks again - that's why I love this forum.

Offline catstevecam

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Re: Broken footpeg - anyone else?
Reply #16 on: May 24, 2020, 04:01:36 PM
*Originally Posted by timur [+]
There is something strange on this picture - you footpeg is attached with threaded bolt instead of OEM pin? I'm sure this is the reason of footpeg breakage - footpeg hole is supported by threaded part of the bolt. The thread fillets acts as crack initiators - they leave marks on soft aluminium and lead to stress concentrations in a hole.

I mean - you can use threaded bolts for this purpose but the threaded part mustn't contact with holes in footpeg and mountings. If the same bolt is used on other footpeg I would suggest you to replace it too preventively - probably it has cracks.

And once replaced both footpegs use bolts that has enough non threaded section - thread should never be in contact with the hole.

Regards

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Offline Flash88

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Re: Broken footpeg - anyone else?
Reply #17 on: May 24, 2020, 04:30:23 PM

Offline ewryly

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Re: Broken footpeg - anyone else?
Reply #18 on: May 24, 2020, 04:40:19 PM
Lots of good info in this thread! That sort of generous, knowledgeable sharing is one of the many things that make this site so valuable!

Offline Oyley

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Re: Broken footpeg - anyone else?
Reply #19 on: May 24, 2020, 04:45:52 PM
Now I have seen that link I am not surprised that there was a failure in addition to my previous observations,as the peg is not supported in the way it was originally designed for.
That method adds leverage plus any slight over torque on the bolt could induce additional  stress on the peg 'forks'.
I would suggest it probably adds that extra stress without the bolt even having that extra torque applied.

 



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