Carbon torque arm failure
 

As reported on:

http://www.ducati.ms/forums/showthread.php?t=59015

"Something odd happened, and I thought I'd share;

Some time ago, my wife was riding her FE, and she pulled away from a stop to a sudden grinding and chaffing sound. She pulled over and we found that the carbon fiber strut connecting the under-hanging rear brake caliper to the engine had snapped and the caliper had rotated around with the disc. The stub of the cf strut jammed into the disk... yada yada. Not a pretty picture.

The carbon fiber was a very cool part on the bike when she obtained it. It replaced the stock aluminum one and had identical end fittings. The break was about mid way in the cf. The end fittings did not fail.

On close examination of the part, and a review of the road we were on, my theory was that the cf did not pull apart, but rather compressed and then exploded. I believe before she noted the sound, my wife was holding the bike on an uphill grade at a stop light. Lets call it about 15 degrees. I think she held the bike with the rear brake. It appears that when doing so, the only thing preventing the caliper from rotating backward with the disc is the strut. Remember that the caliper is not otherwise attached to the frame except at the pivot point at the axle. We know that cf is unidirectional, and I guess if she let the bike slip a bit and then clamped on the brake, the cf strut compressed and failed.

Has anyone else this part on their SP or FE? Any one else heard of such a thing?"

I nearly bought one a well to convert to USD caliper - glad I'm sticking with old school Alloy now.

Cheers - F.

It's good that the lady in q was unhurt, so this is only a technical problem. Have to say, I always understood that cf once made up was as strong in compression as tension,but I never really gave the matter more than a passing thought.

They are not cheap either

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=010

and the bracket

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=010

When Ducati fitted these to 93 900SL and 888SP5 they were immediately recalled and replaced with the alloy tube

The problem with carbon is that it will not take even a small amount of strain in the wrong direction without starting to fracture, and will then get steadily worse and will catastrophically fail if in a structural role.
If the strut is subjected to repeated compressive forces it will need to be extremely carefully shaped so that it has no opportunity to distort, and really needs sidewall reinforcement to be safe, and it then gets pointless having carbon !
Additionally, if it _ever_ got knocked or hit with a stone, then any tiny chips will be the start of a stress fracture.
I love the stuff for body panels, but I would never use it for structural stuff unless I had a team going round checking it after every time out ;)

I have one on the SP5,but is check it regularly.I believe there have been a few failures,though.

So they can fail due to lack of use then:frog: :lol:

See you at cadwell!!

Ray

Cheeky tw*t.Still got your CBR runaround?;)