My brakes are starting to vibrate when hot. It's not clear if it's front or rear rotors. Assuming the offending rotors have out of spec runnout when cold, I should be able to identify the bad rotors. These are the original factory slotted rotors and have about 18,000 miles on them. Is there way to measure runnout on slotted rotors?

 

Should nt be bad at 18K... I m sure it s the front you feel. I don t think the runout will be measurably different hot or cold. A warped rotor will pulse the pedal hot or cold IMO. Car under warranty?
Maybe you got some grease or similar on the rotor? Rust?

 

The car is a 2014 model with about 30 months in service. Their position is these are not covered by the warranty much like the brake pads. The original pads are installed. I really should have them inspect the brakes.

I agree, it's likely the front.

There isn't any rust but contamination is always a possibility. Maybe some hard stops would wear off the problem. Otherwise, it will be aftermarket rotors and pads.

 

agreed that a few really hard stops could clean them off. I don t agree that it isn t covered. I had a 2010 MB e550 and they had to replaced everything due to the car sitting which rusted up the rotors and they tried to clean them but couldn t. They weren t happy but I insisted that a car at this price shouldn t be causing me brake concerns this soon. I d pressure the dealer again and maybe threaten to find another!

 

That happen to my GTS. Got new rotors and good to go.

 

Brought my TTS in for service and technician advised that Porsche discourages use of tire dressing / shine. Don't know ramifications of the residue dissipating into the brakes rotors pads ????? Can anyone shed some light because dress stop tires really sharpen the appearance !!

 

well stands to reason you don t want silicone stuff on your brakes/rotors. I hate the shinny look and after a good brush wash, dress them with a little 303 or similar by putting it on rag and tire and then wiping it dry.