Hey guys, when I'm driving on the Interstate or highways at faster speeds such as 65 and up when ever I hit the breaks the car shakes a lot. It almost seems like when I hit the breaks the front two wheels are moving side to side very fast. When it happens the steering wheel also shakes quite a bit. Any ideas what could be causing this to happen? I feel that if I let it get any worse I might lose control from it shaking so much.

 

Replace or resurface your rotors.

 

Warped Brake rotors... my S4 was like that when i bought it. You will need to replace them.

Josh

 

+1 you won't really lose control but it will shake the crap out of your car which isn't good.

 

Don't cheap out on your rotors, either. Go for Brembo, ATE, Raybestos Advanced Technology, etc.

 

Agree with all of the above... definately need some new rotors...
Now might be a good time for an A8 upgrade since you have to spend a little money anyway!

 

Yup, you need new rotors! I would replace the brake pads at the same time, they are cheap in comparison.
Here is a GREAT forum link for "Adam's Rotors"- i have not found a rotor of higher quality for the price, ($300 all round for 4 slotted/drilled rotors!)

http://www.audizine.com/forum/showthread.php?t=322992

 

'Warped' rotors are not always warped... in fact, most arent. Take it into a brakes shop and have them look at them first. You might just get away with a resurface... proper brake break-in is a must to prevent stuff like this.

 

That's true. They're often, if not usually, victim of the brake pads depositing material on them.

Also, do not buy drilled rotors. Ever. Ever! EVER! All they do is make your rotor MUCH weaker. http://www.google.com/search?q=cross...+rotor+cracked

 

One other thing that may cause that feeling is the Anti-lock Braking System. Have the rotors, alignment, and steering connections (tie-rods) all checked first, however. The ABS system is supposed to rapidly pump the brakes faster that you can. When they first came out, state police got into wrecks because they thought something was wrong with the car and took their foot off the brake for a second in response. Just one more thing you can rule out, after you go through the above checks.