KTM 625 bent footpeg bracket

[steve burrMember]

Calling LC4skin.

How did you go with this? You may remember we talked about this problem when we went on a ride with Garry to find the plane near Meryla. I thought I had mine licked with 12.9 grade bolts. After today it seems not.

Story with mine is that the bike was dropped hard before I bought it and the bracket was bent. I straightened it and replaced the bolts. It droops as time goes on and needs rebending, not a major prob. However today I stuffed up a small jump off a ledge badly and ended up coming down hard with all my weight on the left peg, bolt snapped clean off. Also because I rode around with only one bolt and the bash plate holding peg in place it has elongated the front hole and cracked the web.

Want to know how you went so I can decide how to proceed.

Thanks,

Steve

[Matt BakerMember]

Hi Steve ive sent you a private message letting you know how i got it sorted

[GregMember]

Let us all know how you fixed it LC, could help people in the future

TB

[Matt BakerMember]

Hi Steve

since i snapped the original bolts off i have replaced them with 80,000psi ARP bolts, which were originally designed for bolting together a chrysler V8, and i havent had any problems. Although i had to use a die grinder to get one of the snapped off bolts out and it ellongated the hole, so i put the bolt right through and put a nut on the other side. The peg bracket is a bit bent, but it doesnt worry me too much

[drewMember]

something like this

i’d say, a conrod bolt.

i’ll be interested and will watch here as i’ll be replacing the cast steel one with one of these brackets to fit the Pivot Pegz.

[steve burrMember]

Have been looking around the net at this problem and fasteners.

I think the root of my troubles was with me straightening the bracket in the first place, I probably stretched the bolts creating a weak point for them to fail. I should have straightened the bracket then removed it, file both faces to ensure they are true and replaced the bolts.

As for fasteners I reckon your ARP bolts are in fact 180 000 PSI, they are also now available in 190 000 PSI. As they are a heap easier for me to get hold of I am going to go with Unbrako set screws, their 12.9 grade screws have 190 000 PSI tensile strength, so presumably (I aint no engineer) their sheer strength should be as good as the ARP.

I couldnt find specs on the ARP hardness, but then again I dont believe this will be a issue in this application. Please correct me if Im wrong.

Steve

[drewMember]

they also do a “wave-loc 2000″= 220 000psi http://www.arp-bolts.com/Catalog/Catalog.html

however i think your choice of the socket head cap screw is a better one, as the arp rod bolts you are supposed to to use a stretch gauge to get the proper tension on them, as they recommend this over using a torque specification.

and being you would have to buy a pack of the arp and the wave lock at around $200 for a V8 set (last set i got a few years ago) .

and the unbreko will do just fine and at a few $$$$ at most too. and will be much easier to get in the right diameter . not all the rod bolts have a straight shank. and an oval/ rectangle head.

[GregMember]

I wouldn’t go to super hi tensile bolts on my foot peg mount personally. Such high tensile bolts have no flex and the bolts need some flex because of the fact the weight comes and goes all the time, that and impact hits means that if or when they break again you cant drill them without a major headache. I use a grade 8 and change them every 6 to 9 months.

XR650’s also suffer this problem, some people dowel the mounts that helps, but all the overseas sites I have looked at say be careful of to high a tensile as the bolts need some flex

Just my thoughts

TB

[drewMember]

am i correct in thinking (somewhere in the memory stores) that the higher the tensile rating, the more prone to shear failure?

as they are meant for load on the length of the bolt i.e. clamping strength not side/ shear load?

[steve burrMember]

I could well be off, but. The tensile strength of a bolt is how much force can be applied (stretching) before it tears apart. In my head if you appply a force approaching the max tensile strength you will elongate the bolt and work harden the material, dramatically reducing the tensile strength. So the idea of using a lower tensile bolt to allow it to stretch and take the movement seems counterproductive. Also the amount of force required to stretch and fatigue a 12.9 grade fastener would surely exceed the 8.8s yield force.

From the posts above I have no doubt Moto can shed some light on this. If not from time to time I work with mechanical engineers, I will harass one of them with the question

[steve burrMember]

xy-transit wrote:

Quote:

am i correct in thinking (somewhere in the memory stores) that the higher the tensile rating, the more prone to shear failure?

as they are meant for load on the length of the bolt i.e. clamping strength not side/ shear load?

Rough rule of thumb for standard type fasteners is the shear strength is around 60% of tensile strength.

[GregMember]

xy-transit wrote:

Quote:

am i correct in thinking (somewhere in the memory stores) that the higher the tensile rating, the more prone to shear failure?

as they are meant for load on the length of the bolt i.e. clamping strength not side/ shear load?

Thats what I was trying to explain, they will break and be way to hard to get out

Cheers XY

TB

Birdy told me you found a bladder XY :laugh:

[GregMember]

steve wrote:

Quote:

From the posts above I have no doubt Moto can shed some light on this. If not from time to time I work with mechanical engineers, I will harass one of them with the question

Thats the go Moto will be able to help he is very switched on for a Pom but switched on none the less

TB

[drewMember]

Trailboss wrote:

Quote:

xy-transit wrote:

Quote:

am i correct in thinking (somewhere in the memory stores) that the higher the tensile rating, the more prone to shear failure?

as they are meant for load on the length of the bolt i.e. clamping strength not side/ shear load?

Thats what I was trying to explain, they will break and be way to hard to get out

Cheers XY

TB

Birdy told me you found a bladder XY :laugh:

:blush: Yes TB , i found a bladder on my first ride using the Hydration pack from Sutto’s :blush:
while looking for space to fit Menace’s can of tyre foam i happened to notice a some velcro, and i thought oh an extra pocket that i had not noticed before :unsure:
and guess what, there was a light blue bladder in a plastic bag :blush:

so now there are Menace, Sutto’s AND now TB chuckling at my ignorance due to my inexperience :S

Oh well if you’re laughing at me, at least you are leaving those with a lower tolerance for being teased alone :huh:

. :silly: :blink: :laugh: :laugh: :woohoo:

[steve burrMember]

My new footpeg bracket has arrived. I knew when I ordered it that it had superseded, now I have it I can see what has changed and that they have adressed one of the issues.

If you take a look at the photo the stalk behind the rear hole is a lot thicker now. This will address the bending issue, whether its enough or not time will tell.

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