Steering, Braking or Suspension

Stupid dumb bum question.
SOMETIMES mainly when braking (but not limited to) at around 55-70 my front steering wheel goes mental whith vibration, this has been happening since i had new tires put on the front, i have since had the wheel re-balanced twice and then it started occuring again.
i replaced the front discs and pads and seemed to go away for a little bit
i've then had my wheels remove for refurbing and theyve been balanced again and still to this moment im getting excessive steering wheel vibration.
i also think that there is some delay in the steering of the car.


note: when changing the discs, i found that someone had used an angle grinder or some other type of rotary cutting machine to remove the previous disc, the stud of the old disc retaining screw is still there. im planning to remove this and put a proper stud in this weekend, i dont imagine this will do much but anyone else have any ideas in the mean time?

thanks, Andy :)

Remove the wheels and check the discs for face run out, is the hub face damaged where the disc sits, what happens if you put the rear wheels on the fronts? Do the calipers slide nice and free or sticking and only braking on the piston side of the disc.

When new disc was fitted over the broken stud, was the small hole lined up with this broken stud ?.

i've aquired a run out measuring device from one of my friends, i think there is a slight bit on the drives side where the disc sits onto the hub but im pretty sure that its leveled off. I dont imagine sliders are bad, i inspected them when changing the brakes and appeared to be perfectly smooth on both sides but saying that i may check to see if they're sticking a bit on saturday

yeah, i put in the wheel bolts to hold disc in place while fitting the caliper, once getting caliper on i push brake a few times to get the caliper to hold it a bitwhile i get the wheel on

I've managed to remove that stud and installed a new stud. Not driven car much to find out if the vibrating has fully gone but for now it seems like it has. The steering still feels a bit off, all tires are pumped correct and wheel alignment is right. Just feels lighter than it used to. Used to be light at slow speeds and heavier at fast speeds. It's just feeling light all around. :/

Had a good run out and it's no different, still vibrating randomley around 55-70,or sometimes but not all the time be activated by braking.
Steering feels like it's veering off slightly in one direction but can't decide on which direction it's wanting to go :S

If it was mine,I would begin process of elimination by first checking security of steering rack mountings,then checking to see if there is any wear in the track rod ends and the
ends that attach to rack,I would then expect to have to replace the discs again after refacing hub mating surfaces, Having said this I am not familiar with A5,but I do know that even
small wear in rack joints can cause similar problems to yours.

Sorted the vibrating, near side front rubber brake line looked like it got caught in something and stopped the caliper from releasing, caliper had rusted inside so replace this and the rubber.
Still leaving the steering feeling like the center of rotation is where you're sat