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Old 05-22-2019, 09:08 AM   #1
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Replace clutch if installing lightweight flywheel?

My spec Boxster could use the lightweight AASCO flywheel but am I right that if they're in there replacing the flywheel, I should just have the shop replace the clutch and pressure plate as well with the Sachs units?
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Old 05-22-2019, 09:26 AM   #2
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If the clutch was not recently replaced, you probably should, particularly since you're driving it hard i.e. racing.

The extra $300 is a drop in the bucket.
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Old 05-22-2019, 07:12 PM   #3
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My spec Boxster could use the lightweight AASCO flywheel but am I right that if they're in there replacing the flywheel, I should just have the shop replace the clutch and pressure plate as well with the Sachs units?
You need to. The stock clutch won't play well with the aasco LWFW: no springs.
Get the sachs unit and be done.

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Old 05-22-2019, 07:34 PM   #4
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Oh, and you won't be $300.... Haha. Sorry. The pressure plate and disc will set you back $800-ish.

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Old 05-22-2019, 08:05 PM   #5
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Thanks for the response guys.
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Old 05-22-2019, 10:12 PM   #6
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Thanks for the response guys.
Fwiw: yes, we're talking an expensive clutch. But when I did it, I weighed the flywheel and clutch so I could compare: we're talking 23 LBS reduction in weight! That's HUGE! And yes.... you'll feel it. Wakes the motor right up!

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Old 05-23-2019, 04:22 AM   #7
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You need to. The stock clutch won't play well with the aasco LWFW: no springs.
Get the sachs unit and be done.

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As in won’t function properly, or won’t last long? I have the LWFW with a stock clutch and it works fine in a race application
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Old 05-23-2019, 04:33 AM   #8
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As in won’t function properly, or won’t last long? I have the LWFW with a stock clutch and it works fine in a race application
the theory is that the stock clutch disk has no springs on it and when that is combined with an LWFW with no dampening, you transfer a lot of vibration back and forth between the tranny and the crankshaft.

For a race car, especially one with a tranny that is already a bit dubious on reliability, I wouldn't be too concerned that this will be any worse than a sprung clutch.
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Old 05-23-2019, 07:25 AM   #9
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Be sure to have it balanced before install, ideally with pressure plate.
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Old 05-23-2019, 07:42 AM   #10
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Hmmm..... I may need to back up on what I said below then.
When I did mine, I was told by several racers that the disc needed to be sprung or it wouldn't last without the cushion of the dual mass fw. If that's not the collective experience, then I'll defer to those with more experience.

I was excited, though, to drop that much weight from the rotating assembly.
As byprovider suggests, it's a good idea to have it balanced with the pressure plate. I always do that when I'm building a motor, especially one without external balancing / damping. That said: the aasco fw and the sachs pp were so very close to balanced already, I was impressed. A couple of small divots was all it took.

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Old 05-28-2019, 09:41 AM   #11
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the theory is that the stock clutch disk has no springs on it and when that is combined with an LWFW with no dampening, you transfer a lot of vibration back and forth between the tranny and the crankshaft.
agreed. i would suppose as a racer you're rev matching pretty well so the shock to the driveline is reduced and maybe that would explain why you haven't had trouble.
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