Yeah the mechanical calipers on Dahons with disc brakes were awful too; Piston only extends on one side, and the mechanical cam and ball mechanism has no seals to keep from dirt contamination, which happens almost instantly when riding in rain. Problem is, Dahon "innovated" by offsetting the discs 15mm inboard, ostensibly to reduce incidence of damage, but that means, that to replace the calipers with good ones, you need to replace the hubs, for standard disc spacing.