break issue

[bmimily]

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

Anyone know what it could be?

thanks

[Boxster101]

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

[chris97boxster]

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

[Spinnaker]

Originally Posted by bmimily

My car shakes when breaking at +60mph. its fine at slower speeds.
Anyone know what it could be?

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

[ppbon]

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

[gthompson999]

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.

[gthompson999]

Also someone posted a while back to this forum here:

http://986forum.com/forums/showthread.php?t=23013&highlight=fire+extinguisher

with a link that moved to here:

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