How to Tell the Difference Between 1998 Ford Escort 9.25 or 10.25 Rotors
- 1). Notice the various surfaces on the brake rotor. A circular shiny section on both sides of the rotor is where the friction pads of the caliper engage when braking. Run your fingers across this surface. It should be smooth with little to no grooving. Inspect the holes where the lug nuts protrude for any hairline cracks or wallowing. Also check for discoloration in the metal. A bluish tinge indicates excessive heat and potential warpage. Discard the rotor if excessive grooving, hairline cracks or discoloration are present.
- 2). Lay the rotor on a flat surface and measure the diameter. Write this measurement down when ordering a new rotor. Different vehicles, sometimes of the same make, can measure differently. A 1998 Ford Escort GT may have a 9.25-inch or a 10.25-inch rotor, depending on the VIN number.
- 3). Stand the rotor on edge. Using a micrometer, measure four different areas around the friction pad surface and write them down. Examine the rotor on its hub edge and inner rim. Look for a grouping of numbers that mention the minimum diameter allowed. Compare this number with the smallest measurement you took. If it is less than the embossed number on the rotor, then discard it -- by federal law, it can not be used. If the measured number is greater than the embossed number, the rotor may be turned on a lathe as long as the final thickness is still greater than the discard measurement. If reusing the rotor, thoroughly clean it of any dirt, oil, grease and excessive rust before reinstalling.
Source...