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Old 03-30-2019, 09:07 AM   #1
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Talk to me about flywheels

So while transferring over the ancillaries from my dead Boxster engine to my reborn Boxster engine, I noticed that while the clutch, pressure plate, and flywheel looked good, the flywheel spring-back test failed. The last times that I drove the car, I didnít notice any problems or vibrations with the clutch. Iím thinking that I need to replace the flywheel because of the spring-back test, but Iím not sure why. Any knowledgeable opinions?
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Old 03-30-2019, 10:31 AM   #2
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Originally Posted by NewArt View Post
So while transferring over the ancillaries from my dead Boxster engine to my reborn Boxster engine, I noticed that while the clutch, pressure plate, and flywheel looked good, the flywheel spring-back test failed. The last times that I drove the car, I didnít notice any problems or vibrations with the clutch. Iím thinking that I need to replace the flywheel because of the spring-back test, but Iím not sure why. Any knowledgeable opinions?

That is the only part that absorbs harmonic vibrations. Just think about how well it will perform 5,000 miles from now, do you want to do this same labor again this summer?
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Old 03-30-2019, 12:46 PM   #3
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The last times that I drove the car, I didnít notice any problems or vibrations with the clutch.
sure about that? your engine may have noticed a problem. did you ever determine why the engine popped? what did the crank look like?
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Old 03-30-2019, 01:36 PM   #4
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I haven’t had time to complete the teardown of the old engine. Mostly concentrating on getting the new one up and running. I suspect an oiling issue which may have been my own fault. I found some gasket material in the sump from when I installed the deep sump. This may have clogged some of the passages. We’ll see when the post mortem is complete.
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Old 04-04-2019, 12:46 PM   #5
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So I just received a new LuK flywheel. I opened the box and placed it on a bench. I tried the spring return test and guess what: exactly the same return (or lack there of) as my old flywheel. So WTF?! $500 poorer!
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Old 04-04-2019, 03:21 PM   #6
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So I just received a new LuK flywheel. I opened the box and placed it on a bench. I tried the spring return test and guess what: exactly the same return (or lack there of) as my old flywheel. So WTF?! $500 poorer!
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Old 04-04-2019, 04:12 PM   #7
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Fwiw....

....all of the folks I trust who know these cars inside and out tell me to stick to the factory flywheel.

That harmonic balancer built into that OEM flywheel is critical in keeping the crankshaft from grenading.
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Old 04-04-2019, 04:48 PM   #8
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JFP, thanks for the info. According to this procedure my DMF is fine after the first criterion, i.e. no abnormal transmission noises. However, continuing on to the next step, it doesn’t return to the original position. But then neither does the new one, fresh out of the box. The following criteria do not apply. So, what should one conclude?
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Old 04-04-2019, 04:54 PM   #9
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Originally Posted by 10/10ths View Post
....all of the folks I trust who know these cars inside and out tell me to stick to the factory flywheel.

That harmonic balancer built into that OEM flywheel is critical in keeping the crankshaft from grenading.
AFAIK, LuK is the flywheel supplier for Porsche.
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https://www.youtube.com/user/12shoes2
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Old 04-04-2019, 05:22 PM   #10
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Cool....

....just adding my .02 for the collective.


Good luck.
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Old 04-05-2019, 05:50 AM   #11
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JFP, thanks for the info. According to this procedure my DMF is fine after the first criterion, i.e. no abnormal transmission noises. However, continuing on to the next step, it doesnít return to the original position. But then neither does the new one, fresh out of the box. The following criteria do not apply. So, what should one conclude?
If the new flywheel does not pass this simple test, it is bad. Defective parts right out of the box are not unknown.
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Old 04-07-2019, 03:41 PM   #12
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Yes you need a new one, yes you should go with the dual mass flywheel and yes it will keep your engine from going off like a grenade.
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