Porsche 911 GT3 Cup 2018 Techical Manual page 209

Chassis
911 GT3 Cup (991 II)
208
Repair instructions
NOTE
A repair kit with seals and pistons is available, as well as a repair kit containing only
seals. Pistons have to be replaced only if they are mechanically damaged. The service
life of the seals is 60 hours before they have to be replaced. Under extreme
temperature load, they may have to be replaced even earlier. This is indicated by
sluggishly moving wheels or stuck pistons. Repair kits can be purchased at Porsche
Motorsport.
Refer to the maintenance section, chapter 7.4.7 „Replacing the piston seal rings"
MY 2018
Cleaning Brake system
Damage of piston seal and brake fluid reservoir
Do not use brake cleaner, cleaning benzene, cleaning
solvents, all spray oils (e.g. WD 40).
 Use isopropanol or ethanol for cleaning
Version: 4/20/2018