font disc brake clicking noise

[miklekrs]

hi, is it ok to post here about ebikes? i'm not sure, but the issue is about brakes in general.
trek marlin 8+ fitted with shimano br-mt420 calipers and the front brake has a clicking noise braking from speeds higher than 8-10mph. the disk is true i checked the pistons all 4 are moving freely, i lightly sanded the pads and degreased with brake cleaner, it made no difference.
thanks

 

[figbat]

Sometimes the pad separating spring can get bent and catch the vent holes in the disc.