One problem related to brake disc rotor has been reported for the 1998 Volkswagen Jetta. The most recently reported issues are listed below.
The front disk brake rotors were undersized in diameter. This allowed the disc brake pads to wear in a manner that allowed the pads to contact outside of the rotor and result in reduced pressure on the rotor. Photographs of the problem are available. Brake fading and loss of breaks from overheating on mountain roads then occurred. The car model is a Volkswagen Jetta tdi model year 1998. The car was bought used but it would be unlikely that the disk rotors would have been replaced with less than 80000 miles.