Good Evening Everyone,

I have been recently fixing my car and I have changed SATZ QUERLENKER + KOPPELSTANGE KOMPLETT 10-TEILIG BMW 5-ER E60 E61 520-550 | eBay and QUERLENKER LENKER SATZ SET VORNE KOMPLETT 6-TEILIG BMW 5-ER E60 E61 | eBay and my did not had any vibration and now this weekend I went to change Front and Rear break discs, but front discs were 15 mm smaller and do not fit my vehicle and its in a bad state. When I drive 120 and press brakes I get unreal vibration I believe that front break discs are causing that, But now I have a strong vibration in car when I drive 80 or more. Not idea why. The vibration is awful wanna find out what could be the issue, could it be front break discs causing it because they are in really bad state. HELP

 

If the vibration occurs only during braking and the vibration is felt in the steering, then very very likely the front ROTORS (aka discs) are the cause.
On the other hand, if the vibration persists at all times, have the wheels balanced.

 

I expect to go to garage where I get all my four wheels balance also might also do the tracking while in the garage at the same time. When I drive 120-or more and by hitting brakes I get strong vibration on steering wheel and seat has a small vibration. When I drive >100 then its all good. I am waiting for front brake discs as my vehicle has 324 mm discs and I got only 310 mm..

 

By using a smaller diameter brake disc, your brake pads might also need to be replaced.

With a 7.5mm smaller radius brake disc, your brake pads (outer portion) were not completely making contact with the brake disc. Make sure the pads are not damaged.