i think you should shift some power from garens q into his spin.
juggernauts should be good at taking extended fights, and dealing sustained damage.
right now it feels like one of the reasons garen is even decent, is because of the amount of burst he can create with his q together with 
i wish you would give him some adjustments to actually win extended fights in melee range, instead of being forced into this weird q burst/hit and run playstile.
currently it feels like either you manage to burst down an opponent in the 1.5 seconds before the silence runs out and they disengage, or youre useless.
there is a reason why
became less and less popular. the item is made for extended trades, which garen sucks at in general, since he just lacks proper sustain tools to keep himself in the fight.
i would gladly trade those 40 damage you added to his q for some notable more damage on his spin, and an attack speed scaling to the ability.