Bonding alloy postmount adapter 2 Girvin Elite leg

[junkster]

Hi,
  in my earlier post concerning compatatibility with Girvin Elite Crosslink legs and Vector components etc, I mentioned I wanted to bond a homemade alloy postmount adapter for a Magura Julie 2004 caliper with an 8" rotor.

What's everyone's advice on bonding alloy to alloy?
I have used JB weld but this is alongside clamping the alloy around the leg. I am interested in a variation on OP's crosslink mount.

I have seen OP's and other alloy adapters bonded to carbon crosslinks with strong epoxy. However I assume the Carbon reacts the the Epoxy as a better bonding surface. Will this be strong enough for the stress involved alloy to alloy, providing it is the same design and has enough surface contact between them?

I have been running the 8" rotor fine on my Vectors, see my gallery, but the postmount adapter, (originally an IS adapter with an extra adapter), is way too heavy and looks  [smiley=diaper.gif]   [smiley=laughing.gif]

The Elite legs look far stronger than the vectors and feel lighter.

Any ideas?  

D  [smiley=beer.gif]

ps sorry 2 all those having already read my earlier postings, for regurgitating it again.  [smiley=beer.gif]

[Old Proflexer]

the epoxy should be bonding with the resins and available carbon fibers at the surface on the carbon models.

i've 'jb welded' some things before and i should imagine that they'll stay that way til the second coming.  

the stresses on the bond are minimal if you distribute the stress over a larger area with a plate similar to mine.  the braking pressure is into the leg on my basic design - if you mount the caliper properly, all the force should be to the center of the leg putting minimal forces on the bonded joint.

OP

lets all see a pic or two of what you want to do before you glue it up -
there's a lot of engineer types hangin out here that are a lot smarter than i am.

[junkster]

cheers OP - advice from the originator of the mod - I am truely blessed!  [smiley=beer.gif] [smiley=nod.gif]

What about the postmount and 8" rotor factors? Because the caliper has to be mounted that much further away from the leg, so more leverage stress is applied surely?

Let me know what you think. Then I can perhaps  mod your design for the postmount and let you have pics for more advice on the bonding. So JBweld as opposed to a similar Epoxy bond used with the Carbon crosslinks is advised eh?

cheers

Dan

[Old Proflexer]

an 8" rotor would only mean that the caliper mount would be higher up on the leg and angled a bit more.  the higher up on the leg you go - the more force is applied to the very, very, very, very thin aluminum in the leg - i don't recall off hand how thin it is but you can measure by calipering the leg then the dropout just below the joint, subtract one number from the other and divide by two.

i've done a bracket for the aluminum legs and run the bike gently successfully -
b.t.w. it was a carefully handcrafted removable bracket that slipped under the skewer and ran up the back of the leg on an aluminum number that kiwi and i had been passing back and forth across the equator.

but we risk hearing any number of the "f" words -
such as "failure" - if the leg gives way.  

remember, the 'v' calipers distributed the stress of braking over two legs and a disc is on one.

OP

[junkster]

Hi Op,
        sure. I will be installing the alloy brake booster and am thinking of a little mod to the design that will strengthen the leg.

This aluminium leg adapter you and Kiwi used - do you have a picture of it? [smiley=beer.gif]

cheers,

Dan

[kiwi]

Op isnt talking about the adapter,he is talking about the crosslink he tried it on.At one time it had some kiwi work experience before i had to send it home again

[junkster]

Hi people, another question, (thanks for your input so far) - the materials used - would you have to take into account their individual reactions to the heat created in use - ie different alloys and the bonding agent expanding/contracting at different speeds - would this cause the bond to weaken/fail, (little confused as to how it wouldn't be affected).

cheers, [smiley=beer.gif]

Dan