60mm die spring from Amazon
https://www.amazon.com/dp/B09BTXVLXW?ref=ppx_pop_mob_ap_share
https://www.reddit.com/r/Fanatec/comments/tpax9f/swapped_out_the_black_spring_for_a_die_spring/?utm_source=share&utm_medium=ios_app&utm_name=iossmf
this is the one I used for throttle. i actually just exchanged the blue clutch spring for the yellow, ita a bit lighter
Die Spring