Flywheel weight
 

I just removed the dual mass flywheel from my 1995 993 and it weighs 29.4 pounds.

Wow, I didn't know they were that heavy.

LOL,...They sure are,...........its not something you want to accidentally drop on your feet.

The RS one is about 13 lbs.

Below a 964 RS and GT3 RS flywheel are compared.

The 964 RS weighs 11 pounds and the GT3 RS weighs 8.2.

Due more narrow disc contact annulus, the GT3 uses a different clutch plate and driven disc, otherwise the flywheels are interchangeable.

Material is removed from the periphery of GT3 RS as shown in bottom photo.

http://i541.photobucket.com/albums/g...rlyonScale.jpg
http://i541.photobucket.com/albums/g...ateOnScale.jpg
http://i541.photobucket.com/albums/g...assRemoval.jpg

Wow!....just those periphery machinings remove 2.8lbs/1.27kgs?....hmm, I've got a brand new 964RS f'wheel on the engine at the moment...may have to remove and chuck it on a rotary table for some cunning milling.....

ETA...any chance you could post the dimensions of those cut-outs please? Is everything else the same? (referring to materials rather than using different plate/clutch disc). Reckon I'm ok removing this material?

Ta
Spencer

That is not the only place weight is removed, the friction surface is narrower.

Ah right...thought it was a little too ambitious; from the pics, there didn't look to be that much weight saving in those cut outs.

In which case, the marginal gains are a little too marginal for me. Don't want to go removing material from the friction face.

Cheers though Steven
Spencer.

Do you have a photo or dimensions for the corresponding gt3rs clutch disc & pressure plate?

No, I haven't purchased as yet.

I am looking at flywheels for my spare engine S 2.0L. I would like a lightweight version for street driving. Any thoughts?

Thanks.

Lighter flywheels produce faster revs...can be nice on the track...and a bear to drive in traffic.
Had a very light flywheel in a car once...1/3 the weight of the regular one...burnt out 2 discs in a year of city driving (and I'm not normally hard on clutches)...they can be tough trying to stop and go in traffic.
Bob

thanks for the reply...

Do you think the following flywheel specs would have these issues?

GENUINE 11.46 LBS STEEL FLYWHEEL CONVERTED TO LIGHTWEIGHT - 7.20 LBS

mfc says its a 30% weight reduction, there are some really radical versions out there but that's not for me...thoughts?

Sounds like a Patrick Motorsports description. They make a good flywheel that has the outer area "scalloped" to reduce weight. That's the same way Porsche did it long ago with the original RSRs.

I had a similar flywheel on my 3.2L carbed engine. Throttle response was snappy and clutch actuation with a high clamping force, lightweight clutch housing along with a 6-puck cerametallic disc was not intolerable. It could be driven around the neighborhood no problem.

With the lightweight flywheel, you lose a bit of stored energy in the engine. Meaning, it's easier to speed up and slow down the revs due to the lighter weight. That means quicker throttle response because the engine is less burdened by the lighter flywheel and it is easier to overcome its inertia.

However, the downside is that lost inertia makes it easier to stall the engine when starting from a dead stop. Heavier flywheels, clutches, crankshafts, pistons, rods all allow the engine to resist loads imparted on the engine. When you engage the clutch to begin moving, all that heavy mass does not want to stop spinning- it has a high amount of inertia.

Lighten all the aforementioned spinning or reciprocating parts and you'll find that the engine is inclined to rev up & down quicker because the lighter mass wants to stop spinning more so than a heavier mass. Therefore you have to apply more throttle and be a bit quicker with the clutch to engage it sharply and avoid too much slippage.

My flywheel looked like this

http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/709620-225mm-lightened-flywheel-used.html

Simply adding only a light flywheel isn't going to turn your car into a temperamental beast. The ones that are truly temperamental are those with really light clutches, un-damped/solid clutch discs and super light flywheels. Those are the type that rev like an electric motor, and are really grabby.

Here's an example of a testy clutch & flywheel system.

Welcome to Windrush Evolutions - WEVO - Porsche Products

thanks,

Do you think the size of the motor, 2.0 L, will accentuate the "lightweight" effect or throttle response? Or is engine size immaterial and it all has to do with how much the flywheel is lightened along with lightweight clutch assembly etc. The motor is a "stock" 2.0L S. The internals are all stock.

Yes, Patrick Motorsports would be the part supplier I'm looking at. I like the idea of taking material off an OEM flywheel versus a out of the box lightweight wheel. But, alas I'm not sure.

Well the S already has light stuff in it. Very good stuff. The 2.0 pistons and 66mm crankshaft are considerably lighter than the larger parts in the later cars. For instance a 3.6 has 100mm pistons and a 76.4mm stroke crankshaft with considerable counterweighting. So I do think the lightened flywheel would have a greater effect on the 2.0L than a much larger displacement engine like the 3.0L and greater.

I'm going to go with it.

Its not as if I'm doing something crazy and its not that much more of a cost over an OEM.

So, Flywheel, Bolts (6), Flywheel Pilot Bearing. That would get a longblock hanging on the yoke, eh? The Porsche Parts Catalogue has a flywheel washer 901.102.162.00, not sure about this piece.

Also consider a set of new clutch mounting bolts (the M8 bolts that attach the clutch to the flywheel) because sometimes these are old and the tooling in them is sloppy. Or they're just plain old and it's good insurance to replace them to avoid breakage. They're rather cheap so it's sort of a why-not-do-it reason.

The flywheel washer can typically be reused if i'm not mistaken. It's a steel piece that is rather thick and durable. The later 9-bolt cranks don't even have one. So I never quite understood the need for the 6-bolt washer.

Kevin, thanks for the input. I hit the send $ on the sorta "lightweight" flywheel. I'll post a pic of my goodies when they arrive. Maybe you or someone can give me some install tips.

Thanks again.

-dan