Why does the flywheel matter when you do a clutch job?

Summary:

Jaden explains that the flywheel matters because it is the surface the clutch disc rides on. Over years of service the flywheel gets hot, and that heat causes the face to warp or crack. He warns that cracks are not cosmetic: if the flywheel is cracked too deeply, those cracks will eat up the friction material on the clutch disc, meaning a new clutch installed against a damaged flywheel will be consumed by it. His shop policy is that the flywheel is always at minimum resurfaced during a clutch job, and if it is cracked too deep, it must be replaced outright. He states the reason for resurfacing plainly, which is to restore a level surface, since the flywheel warps over time. This positions flywheel service as a required part of a clutch job rather than an optional upsell.

Answer:

So the flywheel matters because it's what the clutch disc rides on, and what'll happen over the years is it'll get hot and the face of it will warp or crack. If it's cracked too deep, then you need to replace it, because those cracks are going to eat up your clutch disc material. We always at least resurface the flywheel. If the flywheel is cracked too deep, again, you have to replace it. But bare minimum, you resurface it to get a level surface back on there, because it warps over time. That's not an extra we tack on. You're putting a brand new clutch disc against that face, and if that face is warped or cracked, the new disc is going to wear against damage that's already there. So it either gets resurfaced or it gets replaced, and which one depends on how deep those cracks are when we get in there and look at it.