break issue
 

My car shakes when breaking at +60mph. its fine at slower speeds.

Anyone know what it could be?

thanks

Breaking
 

What exactly is breaking? And, has it been broken before?

braking not breaking.....
 

1st check tire pressure...if good
then
Check rotors for warpage due to overheating
If the rotors r brownish purple/blue in some parts of rotor..could
mean they were overheated during some aggressive braking
Best way to check rotor for warpage is to take it to a brake shop
and they'll put it on a lathe and spin it

Warped/cooked -->Replace both rotor and pads
my 2 cents

It's probably "break" dancing, only works when the speed is high enough. :p

It is very rare and almost impossible to warp a Porsche rotor.
What generally is called a warped rotor is brake pad deposits on the rotor face.
Every time the pads go over that patch it will grab a little more, causing the vibration.
This is common at the track, when rotors are extremely hot and people come to a complete stop and leave their foot on the brake pedal.
The patch just cooks for a second or two right to the rotor.
When at the track lift your foot off the brakes just before coming to a full stop and also don't engage the e-brake, leave the car in gear.
Happy Boxstering,
Pedro

Agree with Pedro.
 

This link is pretty comprehensive:

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

You may be able to go out and perform 5-6 hard brake stops (80mph - 20mph) and clear off some of the deposits, just make sure you can drive around without coming to a complete stop before the pads cool down again.

Agree with Pedro II.
 

Also someone posted a while back to this forum here:

http://986forum.com/forums/performance-technical-chat/23013-video-how-bed-brake-pads-rotors.html?highlight=fire+extinguisher

with a link that moved to here:

http://www.essexparts.com/learning-center/cat/brake-pads/post/Bed-in