I guess the failure's reason as you said the modifyed shock mount. On the other hand the factory welding was not done with the proper process. I mean instead of welding the two alloy plates in the surface together, they should make a V shape cut in the joining surfaces, and weld it together in the whole depht. The problem is fixed, as you can see in the prevorius pictures. The after the conversion the suspension became more linear and softer, not as rigid and progressive as the original. Under hard braking I can still feel the shock working, so I satisfied with the result.

 thats good to hear. I don't see any close up pictures of the chainstay at the none drive side, curious if you welded another plate over it? about the welding, i'm no engineer but it makes allot of sence.

also can you share a few pictures/ idea's how to make a floating brake adaptor? the actuall link is very easy to mount to the frame using the main pivot bolt, will most likely let a mate make a stronger one to cope with the extra force. or do you think I need to beef up the main pivot on the frame aswell?

 here you can see the fix: www.pinkbike.com/photo/8394209 each side a 6mm thick alloy plate welded over, and it seems it did the trick. No sign of a single crack appeared yet.
To mount the floating brake rod I recommend you using the main pivot, because only you need to make a custom bolt to fix everything together. www.pinkbike.com/photo/7724829 Otherwise you need to weld a console on the first triangle, but its nasty, and can break easily during a crash (trust me, I did it on my bighit, and it broke)
If you choose the main pivot for mounting point, pay attention to the crank not hit the bolt.

 www.pinkbike.com/photo/7724827

 that thing sure is a beast! nice work.

how did you make the brake adaptor plate rotate on the hub axle? cause there isn't any space in between, you would need to space the seat and chainstay on the non-driveside outwards the thickness of said plate it seems? or is there a more simple trick? thanks for the info's this could be a fun winter project.

 www.pinkbike.com/photo/8839199

 thanks man! that's allot of work to create, need to cut and weld a section in between the chain- and seatstay to make room for the brake plate. i'll talk to a few people who can tig weld it back up, but it has to be trust worthy ofcourse. did you weld everything yourself? didn't even notice you made it a split-pivot design, truelly awesome work.

 Thank you for the compliment, makes me happy and proud About the welding: A professional did it, and I paid for it. I dont had the ability, or experience to do such thing. At lest I not worried about the bike going to fall apart.