disc brake problem

Whenever i pick up some speed my disc is catching and making an bloody annoying sound. I have had similar before when turning hard and the disc flexes but this is happening when im going in a straightline on the road but it is a similar sound that i have gotten in the past when turning hard.
But its constant whenever im going fast.

there is space between the pads and disc, disc is virtually brand new and defo not warpped
Its perfectly fine when in the stand or if im going slow

Its on a lefty fork, mavic crossmax slr wheels with 180mm disc. The brakes are hope tech v2

Any ideas coz its driving me mad and its so hard to try and solve summat that doesnt show itself when they bike is in the stand. Everythings tight on the frame with no play

If you're not getting any noise from the caliper/disc when spinning at a low speed it suggests to me that the problem is located elsewhere, most likely at the hub/axle which is possibly flexing under load at higher speeds, thereby the disc is going through the caliper at a very slight angle and dragging. Just a thought.

get what you mean but how am i gonna find out if that is whats happening

I've no specific experience of Lefty forks but firstly try giving the wheel a good 'rattle' from side to see if there is any obvious play in the axle. Failing that id suggest removing the wheel from the fork and stripping the hub and axle down, giving each part a thorough clean and check for any significant wear. Visualising it in my head I don't see that it can be anything else to be honest.

Just had a good wiggle and i cant feel any movement but its harder to notice if there is any tbh than there would on a normal wheel. I will strip it down this evening and have a look

I get the same thing on my Lefty it may just be a quirk special to them, I changed rotor size from 180 to 160 and it's much better. What brakes/ hub is it ?

wheels are mavic crossmax slr with hope tech v2 brakes
The lefty is meant to be able to take upto a 203mm so god knows, i had a 185 on the front of my jekyll with lefty and never experienced it on that

plus would be a hassle to put a 160 on as my calipers are PM