Big Bu Bu

iTrader: (4)

I'm sure Jeremy will chime in here I hope. I use my car for track days (road race) and never launch the car from a dig. I've been considering the SPEC set up and considering the lightweight options. The 12lb aluminum flywheel seems like a sexy option but a concern of mine would be the driveability on a 3800 lb CTSV. Seems like a better fit for a 32-3300 lb Vette. The Monster guys with the 18lb billet flywheel seem to have plenty of good things to say. That being said I want to give some real consideration to the aluminum pressure plate option from SPEC. So if the SPEC 22lb steel billet flywheel is used, it's going to be 10 lbs heavier than the aluminum SPEC flywheel. Add the lightweight aluminum pressure plate to a steel billet flywheel and you've picked up another reduction of 5 lbs? So now that 22 lb flywheel may in effect be like a 17 because of the weight savings gained in the pressure plate. In addition, I've been told that the weight reduction in the pressure plate is more effective because it is furthur away from the crank so the "lightening" result maybe be greater than the "virtual" 17 lb flywheel. So the big mystery to me in all of this is this. Is the primary concept of the aluminum pressure plate option for weight reduction or rebuildabilty? What is the real effect of that 5lb weight loss on the drive train since it's positioned down stream of the crank? Could the lightweight steel flywheel and aluminum pressure plate offer the same performance as the ultra light 12lb aluminum flywheel with less chance of driveability issue? If it does then it's worth the extra money in my opinion. I've never been able to find anywhere on the internet a users review of the aluminum pressure plate option. Anyone have a link?

SPEC-01

iTrader: (2)

Me, chime in to provide answers, of course...that is what I do! Your number relative to weight savings look to be right. Ultimately, having weight that is closer to the rotational center-line (i.e. the input-shaft in this equation) is key to reducing the MOI of the clutch and flywheel assembly. Because you, like me, are a road-race junkie, happen to have a relatively high-weight car the steel flywheel would be a great option.

Remember, your car came from the factory equipped with a fairly heavy dual-mass flywheel. This was done to provide inertia and dampening because the CTS-V was intended to be a more refined and luxurious car. Going to a steel flywheel will provide a great weight reduction, without being overly light, and pairing this with the Aluminum Pressure-plate will provide a tremendously responsive set-up. In fact, there is a CTS-V with this exact same set-up sitting outside of my window right now!!

Let me know what stage you are considering and I will be happy to provide more specifics on the driving characteristics and a recommendation if needed. Thanks and have a good evening!!!

David_viny

Minor thread hijack. Would the 12lb flywheel and the aluminum pressure plate be insanely hard to drive?

jeejee

iTrader: (3)

don't forget that wheight and weight are not allways the same.

3 lbs from the edge of the flywheel has a much bigger impact in rotating assymbly wheight then 3 lbs from close to the centre


on a side note , bmw motorsport stopped using alu pressureplates, the bennefits where obviously not big enough compared to the reliability issues

Big Bu Bu

iTrader: (4)

Yes, I'd like to know that as well. The car would probably spool up like a rocket though once it hooked up. Noise and vibration issues might be a problem too.

Big Bu Bu

iTrader: (4)

Another thought is that on the track the 22lb flywheel would not drop the R's so quick when down shifting which might make heel and toe a little easier (as opposed to something to light or to heavy). When the clutch is engaged however the lightened press plate comes into play to get the car up to max engine speed quicker. I think I'm talking myself into this. This could also be a good application for a turbo car that needs to keep spooled up during decel.

gnx7

iTrader: (28)

I ran a lightweight aluminum Fidanza flywheel and loved how fast the car revved. I primarily road raced the car but it was a street car for 20K mile in the year that I had it. Granted mine was only 2800lbs. 440rwhp LS1/RX-7

IMO if you are into road racing get the aluminum flywheel.

SPEC-01

iTrader: (2)

Sorry for missing a few responses here...I have been applying some updates that held up my ability to post...go figure...QuickBooks for the win!!!! A great number of people use the Aluminum flywheel and Pressure-Plate and responses to this set-up are great. Of course you will be greatly reducing inertia and this will impact the way the car responds throttle changes and the amount of throttle needs to leave from a stopped position. You all may know Danny Popp, from McClusky Chevrolet, and renowned for his road-racing skills. Well, Danny uses a Stage 3 with Aluminum flywheel and Aluminum pressure-plate in his own track cars and recommends and installs them in lots of others as well. He swears by them...and if I had a car that was going to spend the majority of its time in the mid-to-high RPM-range, or that was going to be tracked regularly this is the way i too would go.

jeejee, Since I have not seen the BMW parts you reference I can't comment on the parts they used or the decision to change direction. Do you have any pics of these plates? I am curious as to the design and whether a steel friction surface was used. I assume it was...but you know what they say about assumption. Yes, removing mass from a portion of the assembly that is farther from the center-line will make a bigger impact than removing an equal amount of material from an are closer to the C-L.

Big, Having a higher mass rotating assembly will allow the RPM's to stay at a higher level for a longer period of time when the throttle is released.

Ultimately you have to make the choice that best suits your needs. If it were my car I would opt for the lightest assembly possible in an effort to shave as much unsprung-weight from the rotating assembly. I understand your perspective though and will be happy to provide more info as needed. Let me know if you have any further questions. Thanks,