The idea came from a bloke on this very forum... rotate the brake caliper down using a stock caliper mount, and a strut mounted to the swingarm on a custom mount and the caliper mount with longer bolt. I did just that along with a swing arm brace welded in place.
http://www.superhawkforum.com/forums/mo ... unt-31513/
It worked for him, should work a treat for me...
Ahh no
The first failure was the OEM caliper mount fracturing.. you can see that in the thread above starting at post 120
http://www.superhawkforum.com/forums/mo ... post380045
new caliper mount was procured and fit, while I searched for a better solution on mounting a by design underslung caliper.
I changed the caliper position, and thus thrust angle by shortening the strut.... By all accounts that worked to lower the stress on the caliper mount however it moved the failure point to the strut material itself.
I made several mistakes..in material selection and design..I also underestimated the amount of force that the strut would need to hold back.
The fix is, all new rod ends as these have been subjected to forces I don't want to trust them to again. Reality is, even the smaller M6 one has a dynamic load limit of almost 20,000lb, and more in compression.. So the mount from the swing arm will fail long before these Chromoly rod ends fail.
Strut material has changed from 13mm dia 7075 al to 1/2mm (12.7mm) dia 4340 vacuum melt cold rolled steel bar.
Threads will be cut like last time, but there will be more material left after cutting threads even though the dia is smaller. Last time I was concerned with the Chromoly rod ends pulling threads from the aluminum bar.. so I used SS thread inserts....which worked,, the threads did not fail... that material failed just ahead of the threads because the cross section was too thin after the oversized thread insert installed.
The failure analysis I did on the first part failed to consider the final OD of the strut at threaded ends (GIGO, garbage in, garbage out) and failed to consider the micro fractures that happen when you cut the material with an edge.. like say a carbon cutter, or tap.. I remembered this from the days I learned about boring motor cylinders and the need to take progressively shallower cuts as you neared the final pre hone dimension...so the final microfractures (about 50% the depth of the cut) would be removed in the rigid honing process. Too bad I did not consider that same concen when I cut threads into the 7075 for the thread insert.
I actually have not found the data I want for cutting aluminum yet..is the microfractures not the same issue because of the elasticity of AL vs the iron bore of a cylinder. Or even if cutting steel like 4340 or other Chromoly steels exhibit the microfracturing I was taught happened with cutting iron cylinder bores.
In any case, I'm not leaving a weak link on the strut rod this time.. 1/2"(12.7mm) 4340 vacuum melt cold rolled steel bar, drilled and tapped m6 on one end, M8 on the other will have a higher load capacity then the shear strength of the fasteners holding it in place or the caliper mount, or even the welded on swing arm mount.
Flame suit on...... Poke fun all you want... we knowingly take risks when we depart from OEM R&D materials and designs . I accepted that risk and lost this time,,,,,, time to try again..
