dizwiz24

Just curious how many others have gotten rid of that expensive boat anchor?

WVZR-1

You've certainly beat on the "dual-mass" a good bit here in the most recent past. If you're such a "hater" just leave it alone. I believe you beat on the "opti" nearly as heavily as you've beat on the "dual-mass".

I certainly hope you've no pets !!!

BTW - there's absolutely nothing wrong with the dual-mass. For any manual shift piece of equipment out there, multiple choices for the component that connects/applies power from the crankshaft to the transmission exist. Flywheel, friction disc and pressure plate choice is very different for the vehicles intended use and driver's feel for the system.

dizwiz24

I think the dual-mass (useless mass. lol) flywheel was developed for the golf-course types and suits who bought C4's more as a fiberglass extension.... and wanted a cadillac like ride.

These were the same people that got the Z51 package discontinued as std equipment (sloshes my soda on the way to palm springs, bad on my back, etc,)

I will concede the lightweight flywheels arent as friendly in stop and go traffic (Easier to stall out). Bad for someone learning to drive stickshift, etc.,
Luckily where I live in ohio we dont have too much stop and go. Thank goodness.

My focus is blistering, C7-beating performance.

Eventually Id like to have literbike beating performance out of my C4.

The dual mass seems to be a step backwards from those goals.

dizwiz24

I also want to note that the transmssion is quiet, when properly shim'd, with an alum flywheel.

Now, yes, I concede its noisy without the shim.

I can only speak for experience with my remanufactured blue tag. But the shim made all the trans noise go away.

So with this info:

Why would you want a heavy mass flywheel????

QCVette

The dual mass flywheels are unique. They are heavy and most can not refinish them. So for some things, they are not the best.

I understand that they were developed to match to the ZF transmissions in order to quiet the gear rattle noise from the transmission. They did that pretty well. Many have been in use for over 100k miles with no issues. Many of them have been raced as well as on the street. I have raced them on a couple cars and also driven them up to 145K miles on my '94.

You are making a lot of unsupported assumptions about the owners and designers of the dual mass flywheels.

They are just a flywheel. Is it the best design? I don't know, but there are other options if you don't like them or have a different purpose.

Good luck.

2VettesMike

192K on mine and still going.

aDigitalPhantom

Don't forget he beats on the LS, and just about every thing like that.

SJW

The majority of owners don't drag race their Corvettes, and very few of your typical Corvette buyers would plunk down $50K for one that sounds like a thirty-year-old diesel Ford truck, even if the salesman did assure them that it makes the car faster.

I also don't think GM realized that shimming the countershafts on these gearboxes could quiet them down, or they did, but found that it doesn't in some cases. I never heard anything about this being a possible solution until I heard of Bill Boudreau mentioning it some 15 years after the last C4 rolled off the assembly line.

It's also useful to remember that inertia works both directions. If shaving your ETs is your paramount goal, have at it. But, I'd like to see reliable data that correlates ETs to flywheel mass. I'd be very surprised to see a difference of >1/10 second gained by reducing FW mass.

I went with the Spec extra-mass SMF when I replaced the slipping clutch in my '94 a few years ago, and I'm very pleased with the results. The car still scoots like a scalded ape, and nobody asks me what's wrong with my car when they pull alongside of me at a stoplight.

Live well,

SJW

scotth48

I put a new one in last year, so its still stock, which is fine with me!

don hall

Was it designed to fit a need?

https://en.wikipedia.org/wiki/Dual_mass_flywheel

dizwiz24

A need thAt doesnt exist when using the proper thickness countershaft shim.

TypicL gm to spend $1000 on a problem that cAn be fixed with a $.50 part.

FASTAZU

I don't mind my DM at all, don't race just drive on the street and with 500HP the extra 10-15 gain from a lightwieght FW won't kill me.

LouisvilleLT4

Another day, another dizwiz thread

LouisvilleLT4

(for the record I'm pretty satisfied with my steel single mass + shim)

dizwiz24

Yes, because 15 yrs of c4 experience fixing, modding, finding out what works and doesnt work is useless info.

Dont forget im the one that even brought to the attention that the zfdoc shim squelches transmission noise even when using a lightweight flywheel (at least on bluetag zf's)

aDigitalPhantom

Fixed that.

1985 Corvette

Having "C7 beating performance" is a pretty tall order. Although I am no expert with the parts, it has been my understanding that the built up inertia in a weighty flywheel for street use has its benefits between gearshifts. An A8 Stingray from a stoplight probably wouldn't be pretty.

whalepirot

Umm, make that VERY pleased.

dizwiz24

Gm has the went to lighter flywheels in the newer cars as cars rev quicker, make more power.

The heavy flywheel idea was for a 190 hp 5.0 tbj v8 that you didnt want to stall out when its wimpy power hit sticky tires if you dumped the clutch at 2500 rpm

The new corvettes have 26 lb flywheels

dizwiz24

Literbike beating performance is the eventual goal. But i wont be there anytime soon.

After actually having/usig a 12 lb flywheel in place of the dual mass the old saying: 'you drop too many rpms between shifts' is a wives tale with big v8s in a lightweight aerodynamic car.

It is true with tiny little peaky 1.7 liter ricebeater style engines that are totall reliant upon rpm to achieve power.

The big v8s have enough torque across a wide rpm range, and enough interti themselves in the heAVier reciprcating assembly that a lightweight flywheel isnt going to hurt you between shifts.

Now, the lightweight flywheel is not as pleasant on the street i will concede... Stop and go traffic is nasty (easy to stall), a real fine line between bog/stall and peel out. Reversing, especiLly up a hill is not as pleasant. Also you may need to downshift sooner when you get ready to climb a hill vs lettingg momentum carry you to the top .

Drag strip launches require finesse/skill but it is possible and repeatible.

I confess im not the worlds best stickshift drag racer, but i do believe this provides a net gain.

I wish someone would come out with a paddle shift for the zf6... Now that would be cool....