Had 12-36 with 48/32 Chainset and nearly all of the b-screw left on the m4000 derailleur, on a genesis cdf. I'd say try it out, 40t might even work without extender if you're lucky.
Yep, two bikes with 11-42 9sp suntour cassettes, one with an alivio a bit older than that which looks a bit different (older style cable routing) and one with an old deore that looks very similar to that m4000.
Anyone here run an Alivio M4000 9 speed RD with larger than 36t cassette?
Weighing up whether I should play it safe or get a ztto 40t and extender from aliexpress.