i am getting a bad shutter/vibration from 40-30 while braking.
This is actually somewhat common... very frequently, it is due to foreign material on the rotor surface, or brake pads, or both.
Typically, a glob of road grease or the like will get up in the rotor/caliper area. When the brakes are activated, the substance is smeared everywhere on the rotor surface and starts to collect in the Galfer cutout recesses.
The "juddering" you are feeling is when the brake pads repeatedly bite into a non-contaminated section of the rotor, and then immediately into a contaminated section, then repeat, repeat, repeat. The clean surface will have a higher coefficient of friction than the contaminated section, so it's almost a sensation of hold/release/hold/release/hold/release as the rotor spins, and this sensation is translated as "juddering" in the handgrips.
The cure: as much as an ***-pain as it is, to really eliminate this problem requires a pain-staking rotor surface cleaning and brake pad decontamination. Ideally, rotors are removed so you can do a thorough, proper cleaning job, including taking about a half a box of Q-Tips and brake cleaner to scrub EVERY SINGLE cutout recess till they are all pristine. Brake pads are removed and scrub on medium sandpaper (using a marble slab or some other absolutely flat surface) until all traces of contamination are removed.
I just went through this exercise on the Hayabusa, and yes, it's a butt-pain. But smooth, predictable braking performance is worth the effort, particularly if one is sorta-kinda pushing the performance envelope.
