i've bought and changed the brake disks again few days ago with 310mm Grooved Roters and now i get a strong vibration when i brake a bit harder from hight speed ,don't know exacly what is it..the disks or the wheels or some bushes ....any ideeas?? i get the wheels balanced again maybe tomorrow and see how it is after...and also in the summer i dropt the car down about 30mm and i've got kyb shoks all around and now is wearing the front tires inside bad and that's way i'm thinking what can it be ..the bushes or i need the adjustable upper link arms...any help will be much appreciated

If it's a vibration only when you brake then it's pretty much going to be brake related.

 

Is there any movement in the capilers ? - any slight movement will cause vibrations

Did you change the pads with the disks ? - old pads on new discs cause uneven surface cover.

 

When you lowered the car did you get the camber adjusted ?. - Dropping or raising the car will throw the camber out, you can fit adjustables to correct the camber or you may be able to get hold of a camber plate kit from somewhere which allows you to use the thickness plater required to stop the tire wear.

Will be worn tension rod bushes

i got new whiteline tension rod bushes...

Nice one, hope that cures it, if not at least you got some nice bushes :).

I put black diamond drilled and grooved discs on mine and had same problem, does not seem to affect brake performance; it reduced a bit after pads wore in, but still there a bit under very hard braking. already had polybushes etc. was told by garage that dics are very very slightly warped, which they said is fairly common on drilled/grooved discs!!!. so will have to live it. under normal braking OK no probs.