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Is it necessary to resurface a flywheel when changing clutch?

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Is it necessary to resurface a flywheel when changing clutch?

 
Old 07-02-2009, 03:28 PM
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Orest
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Default Is it necessary to resurface a flywheel when changing clutch?

So my engine is out and I have performed a long list of WYAITs. My question is whether it is prudent to resurface the flywheel as a I replace the clutch and pilot bearing. It appears smooth and not really grooved, is it part of normal maintenance?
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Old 07-02-2009, 03:32 PM
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Lizard928
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use a flat edge to see how true it is.

But that said, alot will say yes resurface every time. Others will say never resurface as it will burn out your discs faster. The latter info is 100% true IF the machining is not done to the correct surface quality.

But if it isnt burnt, maybe buff it with some sandpaper to take some of the glazing off so that the new clutch beds properly.
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Old 07-02-2009, 03:37 PM
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Cosmo Kramer
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Like Lizard said, I replaced one in my 79 Mustang when I was a kid, just roughed it with some emery cloth and it worked great. Only machine it if it is warped.
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Old 07-02-2009, 03:41 PM
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Orest
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Thanks guys! It looks smooth, I will just remove the surface rust.
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Old 07-02-2009, 04:11 PM
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best to check it with a good straight edge across both sides.
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Old 07-02-2009, 04:41 PM
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The surface gets blanchard ground perfectly flat if it's done right, and will extend the life of the clutch IMO. A new surface won't have any hard spots (those blued and blackened spots on the face now). The perfectly flat surface means even friction across the whole face, so action will be smoother, more predicatble, and will hold more torque without slipping. Seems a no-brainer to me. I have done the disc-sander resurfacing method, and it's just OK, marginally better than no prep at all. Best clucth performance and life seem to happen with flat grinding, especially in hi-perf applications.
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Old 07-02-2009, 04:48 PM
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Daniel Dudley
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If the car drove out well, it would generally be OK to buff it out. If you don't know how it operated, you are taking a chance. If it is rusted and the rust is uneven, that would not be good. OTOH, it's not like you have to pull the motor to get at it if you don't like the results.
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Old 07-02-2009, 05:13 PM
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dr bob
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But the motor is already out, getting a new pilot bearing etc. Best-ever access to those wonderful flywheel bolts.
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Old 07-02-2009, 06:03 PM
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As Colin says, check it with a straight edge, shining light from the back to help you see low spots. Any burnt spots are harder material that the rest of the friction surface and should be ground away. Some examples are visible on my old flywheel, you can see two spots and a third starting near the top of the pic. If it's just a streak of clutch material like the large one at about the 5:00 position it cleans off fairly easily.

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Old 07-02-2009, 06:33 PM
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If you take it in print out the specs and snip off any "Porsche" info. Say it's an Audi 5000. You'll save a few bucks.
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Old 07-02-2009, 08:38 PM
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I got much the same response when I inquired about mine a while back... opinions on both sides. I had several tell me machining would ruin it, but mine was pretty abused with lots of blue spots. Took it to a reputable machine shop, insured that they would only take off the minimum and for $30 it looked like new. That was 14K miles ago and it's still smooth and working great... knock, knock, knock

Bill
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Old 07-02-2009, 08:50 PM
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I should have had mine resurfaced, but instead did it by hand, in-situ. Works fine, though. More than adequate.
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Old 07-03-2009, 12:34 AM
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Chris,
your flywheel doesnt look that bad actually. There are no bluing spots that are visable.

Dave's picture definetly shows almost a blue ring around which would cause uneven wear and would need to be resurfaced. But when resurfaced make sure that it is not too rough of a surface. Most machine shops arent stupid enough to leave it rough. But some are and if it is too rough this is what causes premature wearing.
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Old 07-03-2009, 01:24 AM
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terry gt
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I would machine the flywheel . / to match the presure plate / because its cheep compared to a clutch / because its easy to take off . IMO Terry
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Old 07-03-2009, 12:44 PM
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James Bailey
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It is best to have it machined. That gives a fresh surface for the new friction material to transfer to the flywheel .
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