After removing the DMF it should be inspected for inherent problems. The following list is to be used as a guideline only. It is not a scientific procedure and should not be used to obtain a definitive answer as to weather the flywheel should be used again or replaced.
Having said that, all you DIY ‘s have at it.
1) Check for cracks in the drive surface. If any cracks exist replace the DMF.
2) Warping of the drive surface should be limited to 0.015”or 0.37 mm. Flywheels typically warp like a soup bowl, higher on the O.D. lower on the I.D. A straight edge or a dial indicator will expose how much warp exists. Pic
3) Free rotational movement of the drive surface should be limited to .383” or 9.75mm. This movement can be checked by rotating the drive surface either direction, and then make a mark on the outer edge where the alignment pin comes to rest (center of pin). Then rotate the other direction and make a mark at center of pin. Measure the distance between the marks. Do not force the drive surface. This is a measurement of the FREE travel. One finger is enough effort. Pic
4) Total rotational movement of the drive surface should not exceed 1.720” or 43.62mm. This movement is checked the same way as the free rotation but requires the drive surface to be forced to the loaded position, adding a few pounds of pressure to the alignment pins does this. A little strength is needed to complete the task. Pic
5) Lateral movement of the drive surface should not exceed .065” or 1.67 mm. this movement can be checked by forcing the drive surface downward until it stops. Make a mark at the lowest point. Then push downward on the opposite side making a mark at the highest point. Measure the distance between the marks. Pic
If the DMF passes these inspections consider taking it to a flywheel or clutch shop for further inspection and possible resurfacing.
If your DMF has 125K don’t expect to get the same mileage with the next clutch replacement. If you require another 100+K replace it with a new one.
If you are increasing the HP expect to get fewer miles on a DMF than you would if you had stock power. The same goes for spirited driving and launches they will reduce the life of a DMF.
Keep in mind that a DMF is a wearable item just like brakes and tires so expect to replace it at some point.
The final step for the flywheel is .350" to .345". Do not remove more than .020" from drive surface.