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914World.com _ 914World Garage _ Anyone using a lightweight clutch for AX?

Posted by: nine14cats Nov 14 2005, 01:38 PM

Is there anyone using a lightweight flywheel / 4 puck clutch disk for autocrossing? My new track car has one and I'm not so sure my wife is going to like it. I had heard they are like an on off switch and I have to agree after driving the car. Getting the car onto the trailer was an experience.

I'm worried about longevity as it takes quite a bit of slipping to get a smooth launch.

In my last car I used a Centerforce setup which was easy to use.

Thanks,

Bill P.

Posted by: john rogers Nov 14 2005, 02:03 PM

My vintage 2L car has a kevlar clutch and it is on/off and usually if someone new drives the car they stall it several times before they get going. My flywheel is lightened some but not one of those mega-bucks jobs. For a race car they are fine but not for street use at all. I'd say go somewhere and let your wife practice before going to an event and that will eliminate the embarrassment she might feel.

Posted by: jsteele22 Nov 14 2005, 02:11 PM

I haven't used one, but one thing to consider is why the flywheel is there in the first place. Energy output from the cylinders comes in concentrated bursts, and the (moment of) inertia of the flywheel helps smooth those bursts out. I remember reading that on certain Hondas, a lightened flywheel meant a fairly predictable (catastrophic) failure of the oil pump gears. I don't know how TIV engines respond, but its probably safe to say that the increase in pedal response comes at the expense of shorter engine/tranny life. Anybody have first-hand knowledge, BTDT ?

Of course, if the car is strictly for AX, this might not be a major concern.

Posted by: messix Nov 14 2005, 02:14 PM

think thats bad ? try a button clutch.

Posted by: nine14cats Nov 14 2005, 02:14 PM

Hi John,

Thanks for the info. Yeah..I am going to have my wife practice before we go out. I just was curious as to the longevity of the clutch in multiple launch events such as an auto-x. I don't want to be going through clutches right left. Our Centerforce on the 914-6 was nice and smooth and lasted a long time. This one is different in feel, but if durability is okay, we can probably get used to it.

Thanks,

Bill P.

Posted by: nine14cats Nov 14 2005, 02:16 PM

I haven't heard about the engine life concerns before. The motor itself is a 1995 993 3.6 with a G50 behind it. This car is track only and is ~2200lbs.

I know it nice for the blip/throttle, I just hope my wife feels okay with it.

Bill P.

Posted by: Dan (Almaden Valley) Nov 14 2005, 02:23 PM

Bill
I think Doris will be fine. She is much better than we give her credit for. She is cautious and always safe. Just get her that pre-event practice.
Since the clutch is in there, just use it and don't worry. If it does go in short order then switch to a different clutch set up..
The lightened flywheel will probably take more getting used to than the clutch.

Posted by: SirAndy Nov 14 2005, 02:31 PM

QUOTE (nine14cats @ Nov 14 2005, 12:38 PM)
Is there anyone using a lightweight flywheel / 4 puck clutch disk for autocrossing?

i do and i love it ...
except for the stop and go commuter traffic

i really like the feel when driving the car hard (like at an AX).
and it holds up great, i can spin the 9" schlicks at will in 1st and 2nd ...

(well, i could if i had a running motor)
Andy

Posted by: Britain Smith Nov 14 2005, 03:28 PM

Which set-up did you end up going for? Clutch/Pressure Plate combo that is.

-Britain

Posted by: TimT Nov 14 2005, 03:44 PM

I just bought this clutch/flywheel set up for my 911

http://www.jbracing.com/flywheel-porscheul1.php#early911

I currently have a lightened flywheel in the car, with a 915 RSR aluminum pressure plate. The current set up is very driveable

Im going for the nth degree so I decided to drop some coin and get a ultralightweight unit.
Now I have to remodify the trans from a pull set up to a push

Posted by: nine14cats Nov 14 2005, 03:50 PM

Hi Britain,

I'm looking at the receipts for the parts that the previous owner put into the car. It appears that the flywheel was lightened by a race shop and a Sachs 4 puck clutch disc / pressure plate assembly from Porsche Motorsport was put in. It look to be a pretty expensive setup. The receipt for the clutch and PP comes to $1500 in parts.

Currently the car is getting my Phase 9's hung on it as well as a street setup to make the 92db at Laguna Seca. The previous owner was running the car through headers and oval tips without an exhaust / muffler setup. The car is LOUD!

Bill P.

Posted by: nine14cats Nov 14 2005, 03:53 PM

Hi Tim,

Hi jacking my own thread.

What spring rates are you running on your 911's? I have coilover RSR units in the front and rear. I haven't had time to look at the springs yet to see the rates.

Now...back to clutches and PP's!

Thanks,

Bill P.

Posted by: TimT Nov 14 2005, 04:38 PM

I have #350 front springs with revalved RSR struts, in the rear I have #550 springs and Koni 3012 shocks

My car weighs in around 1900lbs, hopefully less, given that every exterior panel is glass, or carbon, including the roof

Posted by: Andyrew Nov 14 2005, 04:46 PM

I like mine....

Stiff clutch, and on offish.

Nice and livable. Learned to live with it, and I shift better with it, than either of the 944's...

Posted by: carr914 Nov 14 2005, 04:49 PM

Encountered the same problem with my 906 flywheel. It's definitely like a switch. It's real nice at Sebring, but at the A/X we have here on sand, I have to figure a whole new way to drive. Also Tim, the guys at JB Racing are my friends(in fact, talked to Jim this am), they make the FINEST stuff around. If you want to twin-plug your car, contact them 1st.

T.C.