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2020 Clutch and lightweight flywheel ideas w rotational inertia weight questions
With my new fully built Keegan motor on the way it’s time to turn up the boost.
Do not think my current SPEC stage 2+ w nice light 8 lb Fidanza aluminum flywheel is going to be up to the task. Have to change away from aluminum for safety and rule sets. Would like even less inertia.
Yes I have done a ton of searching but things change every year. Not ready for a BMW trans!
Thinking about 285 FT/LB +/- on roadcourse for Time Trial and switched up to 350 ft/lb for HPDE & street. Car is not a daily driver, however do drive about 3K per year to work occasionally and driven to track when not trailered.
Given my choice I would just get a Supermiata 7.25” twin disc clutch with the 12.8 lb. flywheel and (Sprung)440 ft-lbs Kevlar/Carbon discs.
Unfortunately twin sprung discs are not offered, and I’m afraid the solid discs will contribute to prematurely grenading my 6 speed? Shops for built 6 speeds seem to be recommending sprung discs for that reason.
Really like the idea of the SM Kevlar twin as it seems perfect for my application except not sprung as I really like a free revving responsive motor and the other 1.8 options seem heavy?
Next on my list is the SuperMiata Sport puck sprung Clutch w theirlightweight 10.3 lb. steel flywheel 340FT/LB, good yet heavier option, but of course it has been sold out forever and looks like they are routing everyone to the twin. Probably for good reason. Wish an aluminum housing was listed?
Next is the easy button Flyin Miata Happy Meal level 2, 10.3 lb 353 lb/ft. Really seem a love hate thing lately, not sure if they switched suppliers or just had the internet blues.
SPEC Stage 3+ with aluminum backing plate and lightweight steel flywheel ?? Like my 2+ but is starting to slip at 250tq, not much feedback on the 3+ and have never seen the aluminum housing.
ACT HD or Extreme with sprung 6 puck ?? Probably more running than anything, but really are love hate and seem like Extreme really isn't drivable even in pits or on to trailer without winch?
Open to education, ideas, observations and criticism. New yet tested? 7.5lb pixiedust unicorn tears unobtanium steel flywheel?
Notice I did not mention price or noise as they are really irrelevant for this build.
If you have a clutch with reasonably smooth engagement (organic or kevlar), you probably can get by without springs. It'll probably be easier to drive in a track setting (quicker, more positive shifts perhaps?). On the street under normal street conditions, you probably wont notice the lack of springs.
I ran a cerametallic unsprung twin plate clutch on my car for years before eventually having custom organic unsprung disks made. The cerametallic disks were B R U T A L, but kind of fun? Did I mention my 90 minute each way commute??
Why not just run the SM clutch and have some mechanical sympathy.
Really was not talking about the sprung disc soaking up my lack of sympathy. Shift endurance conservatively and never do a stationary launch.
Thinking more about the peak torque vibration amplitude. Softening the big bangs every 180 degrees letting the springs absorb a bit of accel and decal peak value spike.
Seem to remember peak torque spikes sent to the gears is something like 15 times the measured torque?
I don't think your sprung disk or disks are going to make up for any reduction in mass of the entire clutch/flywheel assembly. I run a sprung disk and a stock mass flywheel after talking to folks who build these trannies.
If you have a clutch with reasonably smooth engagement (organic or kevlar), you probably can get by without springs. It'll probably be easier to drive in a track setting (quicker, more positive shifts perhaps?). On the street under normal street conditions, you probably wont notice the lack of springs.
I ran a cerametallic unsprung twin plate clutch on my car for years before eventually having custom organic unsprung disks made. The cerametallic disks were B R U T A L, but kind of fun? Did I mention my 90 minute each way commute??
Well after bouncing a bunch of emails off Ed at SPM I ordered the Supermiata 7.25” twin disc clutch with the 12.8 lb. flywheel and Kevlar/Carbon discs.
According to him the heavy flywheel and clutch combo still has "less MOA than a 1.6 standard setup with an aluminum flywheel". We will see?
Hated to go to the "heavy" flywheel as the race looks so sexy, but sounded like the smart thing to do as the car is still driven on the street a bit.
04-30-2020, 04:41 PM
2020 Clutch and lightweight flywheel ideas w rotational inertia weight questions
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