To To Brake or Not to Brake......that is the Question

[ppbon]

Originally Posted by 442nd986s

So, I've started to notice a small 1/8" shake on my steering wheel ONLY WHEN I brake. It's more noticeable at +30 MPH. All new tires and balance about 5 months ago.
The wired thing about it is that it mostly happends in the mornings and after work (10 hr shift). This makes me to think it's a warped rotor (since it tends to go away after heating up/ 20 mins of use).
The rotors and pads seem to be nice and thick, but I don't know what the minimum thinkness is allowed. Any advise would be appreciated.
3rd owner, no service records, '01 986S with 90k miles.

... it wouldn't un-warp itself when hot.
It's practically impossible to warp a Porsche rotor. I've never seen one.
These rotors are internally vented and are extremely solid structurally.
What people generally refer to as a warped rotor are pad deposits on the rotor's surface.
If you use pads that are not the correct match to the rotor and its use, or if you apply the brakes to a complete stop and hold them when the rotors are overly hot such as after a track session, a small amount of pad material will be transferred over to the rotor.
When you brake, every time that patch passes under your pads it offers a bit more grab and therefore you get the steering shimmy.
The cure is to eliminate this transfer. You can do so by repeatedly breaking hard (even with ABS kicking in) from say 75 mph until the car slows down to 20 mph. Let the rotors cool down a mile or two and repeat.

To know if your rotors are worn to the point that they need replacing, if the wear lip on the edge of the rotor is 1 mm or more they need to be replaced.

Happy Boxstering,
Pedro