Lightened flywheel
10-26-2010, 02:00 AM
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Lightened flywheel
After researching the subject of light flywheels quite a bit on this board, and reading some complaints on every brand on the market (e.g., Fidanza and Spec) I decided to just rework the stock FW.
The weight prior to machining was measure at 15 lbs. After removing a bag full of steel shavings, the FW was re-weighed at 10.4 lbs. Tim Morgan, the machinist, an older gentleman with years of experience in race prepping engine components, decided to leave a hefty ring of steel on the front of the FW, so the diagnostic studs were not removed.
Since a higher clamping force pressure plate will be used (KEP), Tim decided to leave some meat on the FW's front outer diameter, where the diagnostic studs attach. Hopefully, the remaining bit of ring will help stabilize the FW and prevent warping under higher PP clamping loads. This leaves some weight at the periphery, which does affect the angular moment of inertia (Moment of inertia = mass x diameter squared), but this seemed like a reasonable trade - off to preserve the FW's structural integrity.
I'm curious to hear other opinions, since this is untested territory for me.
The weight prior to machining was measure at 15 lbs. After removing a bag full of steel shavings, the FW was re-weighed at 10.4 lbs. Tim Morgan, the machinist, an older gentleman with years of experience in race prepping engine components, decided to leave a hefty ring of steel on the front of the FW, so the diagnostic studs were not removed.
Since a higher clamping force pressure plate will be used (KEP), Tim decided to leave some meat on the FW's front outer diameter, where the diagnostic studs attach. Hopefully, the remaining bit of ring will help stabilize the FW and prevent warping under higher PP clamping loads. This leaves some weight at the periphery, which does affect the angular moment of inertia (Moment of inertia = mass x diameter squared), but this seemed like a reasonable trade - off to preserve the FW's structural integrity.
I'm curious to hear other opinions, since this is untested territory for me.
10-26-2010, 10:57 AM
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$200 for turning off the 4 lbs. and re-surfacing the face. Northern California is not the bargain basement of America, so machine shop rates out here run about $90 - $100/hr.
951Doc
86/87 951's
http://www.project944turbo.com
951Doc
86/87 951's
http://www.project944turbo.com
10-26-2010, 01:15 PM
#4
Nordschleife Master
I had my stock wheel lightened also though i had the entire rear lip machined off. Weight came in at just over 9lbs. I think you will really like how the car feels, much faster response from the engine makes heel / toe easier and also makes shifting smoother due to the faster rpm drop.
I am using a KEP stage 1 with a 930 disc, have about 5k miles on it and its been working great.
Make sure you get the flywheel and pressure plate balanced together before installation.
I am using a KEP stage 1 with a 930 disc, have about 5k miles on it and its been working great.
Make sure you get the flywheel and pressure plate balanced together before installation.
10-26-2010, 01:26 PM
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Three Wheelin'
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I think the logic of your machinest is good, leaving material in the areas he did. The biggest thing i have noticed with lightened flywheels in the 944 chassis is that it definately changes the harmonics of the drive line. Noticed that you hear and feel vibrations you did not before or certainly ones you are not used to.
Starting with a stock flywheel is far better than the china junk out there IMO.
Starting with a stock flywheel is far better than the china junk out there IMO.
10-26-2010, 10:37 PM
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Balance
Yes, Mike Stimsom of Pacific Performance in San Mateo, CA will put the whole assembly, including knife-edged and lightened crank on a Hines dynamic balancer. Everything, from drive pulley (LR alloy) to pressure plate (KEP) will be balanced as one unit.
951Doc
86/87 951's
http://www.project944turbo.com
951Doc
86/87 951's
http://www.project944turbo.com
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10-26-2010, 10:48 PM
#8
Three Wheelin'
What is the merit of balancing everything as an assembly?
I would think you would want all the items balanced separately with the exception of the flywheel and pressure plate. Then maybe double check the assembly.
I would think you would want all the items balanced separately with the exception of the flywheel and pressure plate. Then maybe double check the assembly.
10-26-2010, 11:16 PM
#9
Drifting
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Yes, Mike Stimsom of Pacific Performance in San Mateo, CA will put the whole assembly, including knife-edged and lightened crank on a Hines dynamic balancer. Everything, from drive pulley (LR alloy) to pressure plate (KEP) will be balanced as one unit.
951Doc
86/87 951's
http://www.project944turbo.com
951Doc
86/87 951's
http://www.project944turbo.com
10-27-2010, 12:37 AM
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Everything balanced individually and then together confirming balance, accord to the Pacific Performance Motorsports.
