I have a stock dual mass flywheel that has lost enough of its spring to start making noise when the clutch is engaging it. I need to replace it and I don't know which way to go with the replacement. I would prefer to have a solid flywheel instead of a dual mass. I know I can get either a lightweight aluminum, or steel replacement. I have found that you can also get ones that have a counterweight and ones that don't. If I could get some information about the benefits/ drawbacks of all the different kinds of replacement options, including the benefit of a dual mass over a solid, I would really appreciate it. My car is a 1994 with the LT1 engine. Thanks.

 

Well the one thing I do know is the difference between a Dual-Mass and single. The single mass rattles like hell. It will sound like a bag of rocks is tumbling around in your transmission tunnel. This is just the sound it makes (long technical story spared...), and is not bad. The Dual-mass FW was invented to eliminate this sound and make it more pleasant to drive, at the expense of added expense and weight. So, if you can live with the rattle, then you can get a lighter FW for cheap.

 

from what i've heard, no matter what single mass flywheel you go with, whether it's steel or aluminum, it will make noise. don't exactly know what it sounds like, but this is what i have heard from other people. spec makes a good product, and so does fidanza. needless to say, the aluminum flywheel is going to be lighter than the steel flywheel. it just depends on what you want to do. the lighter FW will get you into the power band faster because there is less rotational mass. but the steel being heavier will be easier to drive because there is that rotational mass that keeps everything moving. hope this helps!

 

This car is a daily driver. The transmission whines enough as it is, so I don't really need any more noise from the tunnel. Would the aluminum flywheel make it a lot rougher to drive on the street?

 

Yes. It makes it much more difficult to start from a stop, since you don't have nearly as much energy stored in the FW. Just takes some re-learning of your muscle memory.

I have heard that switching to a sprung-hub clutch (such as Spec stage 2+ or 3+) eliminates much of the noise, but I'm not sure about that.

 

I just got my car back from a long wait for a new engine, I went thru this decision making process, my engine went the internal balance treatment, the machinist zero weighted (milled off the counter weight) my Dual Mass.


Upon assembly the assembler notice greasy oil oozing from the dual mass, I researched this forever,and could not get a definitive answer, Bill at ZfDoc, Chevy Mechanics, Forum members, no one actually knew if there was suppose to be oil in the dual mass.

Determined and somewhat convinced there was no oil in the dual mass flywheels, I eventually bought a used dual mass from Ebay hoping it would not ooze oil, but it turned out to be junk, had to return it, (story for another day).


Remember I'm into my engine rebuild for around $16,000, so far, so I had to trim costs wherever I can, I eventually bought a SPEC stainless flywheel at 20 lbs, (38 for stock).

Then I went to Summit and bought not once but twice recommended clutch discs, that had a sprung hub, as you well know the discs in our cars were solid, because 1/ the DM dampen the engagement and 2/ it does not have room for a spring pack.

None of the Summit parts fit, all told, I loss a heck on shipping bad and ill fitting parts.


Fast forward, They install the Spec FW( I was able to remove a bolted on counterweight), with the stock albeit 30,000 miles clutch kit, TB, Disc, PP.

Pros: I got it running and did not have to pay 600 plus on a new DM, and to have had to mill it to zero balance, supposedly revs faster.

Cons:When starting off from near idle it bogs, due to the lack of mass and between my cam ( power band) , Super Ram, and poor tune. I hope it improves after the tune.

Noisy at idle, it would bother you, if you are try to work on your engine with it running the box of rock clattering is very very annoying,If you are stop at the light it would bother you; and I have a steel unit, I heard the aluminum ones are even worse.

When you drive, the noise will present itself at around 23-2400 RPMs as a roar.

Moral of the Story, forget the Single Mass, Bite the bullet get the fdual Mass and leave the suffering for the malinformed or the unlucky.

 

On our 94 LT1 (100k), I replaced with GM/OEM parts pilot bearing/DUAL MASS Flywheel/release bearing/pressure plate.

The car shifts like butter -- and it quiet.

Go with the DUAL MASS -- you will not regret it and will forget the $'s spent -- by contrast, go the other way, and you'll be reminded every time you drive the car.

Do searches, there are other sources to get an OEM dual-mass flywheel (e.g. supporting vendors, partsladi (ebay), LUK?, carolinaclutch, etc).

BTW, if your doing the clutch, likely you also should replace the slave cylinder (50k max life) and possibly the master (100k max life) -- read ZFDOC.com.


TO slickFX3,

The dual-mass flywheels DO HAVE oil in them -- sorry I didn't see any of your posts when you were trying to find out.

As I understand it, the oil is used to dampen the movement of the front 'mass' relative to the back 'mass' -- this is the reason why some say the dual-mass flywheel has about a 100k life -- the seals in the dual mass die -- its also why the Dual-mass flywheel SHOULD NEVER be machined...

 

Then if I wanted a dual mass in eventuality, sooner than later, then the machining to take off the counter weight will always damage the unit?

What recourse to I have?, I more likely than not will not tolerate the noise of the single mass flywheel.

Should I build a new engine with an external balanced flywheel, would have been alot easier, but I didn't know enough about that to say no.

This may cost me my sanity.

 

Thanks for all the info guys. It looks like I'll bite the bullet and buy a stock replacement dual mass. Just to let you all know, the only reason I'm even pulling the clutch back out to do the flywheel replacement is that the clutch failed again after being in for only 5 months. I already have a new clutch master cylinder and slave cylinder installed due to both failing at different times. I replaced the original clutch that was in the car because the pilot bearing was worn out. I replaced with a perfection clutch kit (made by Zoom) and had problems from day one getting it adjusted right. The installer used shims since we machined the stock flywheel back to flat. I suffered with it for about 6 months until finally the clutch disk broke apart. We replaced the clutch under warranty and took out the shims. We replaced the fork arm as it was worn. Got everything back together and it was perfect. Everything worked wonderfully. Then, last friday, the clutch failed again. I can shift through all the gears with the engine running, as if I have the clutch pedal pushed. I also have a full pedal, as if there is nothing wrong. What do you think happened? My guess is the pressure plate collapsed. Let me know. Thanks.

 

I'm curious as to how you machined the stock flywheel.

You can find new replacement flywheels for about $700 from various places. Good luck with your car.

 

We sent it to the machine shop and they milled it like they would any flywheel or rotor I assume.

 

I replaced my stock(good) DM FW, with a Fidanza aluminium flywheel.

The car revs faster, making it more easy tp rev mach down shifting.
To me the car as diffently become more exciting to drive, it feels more raw and more like the sports car it is...

It IS noisy though! When the gear oil warms up it it very noisy. And it roars when you cruise, and put it under load too.

If you mainly care about cruise / daily driving do NOT do it...

If you care a little about performance..do NOT do it...

If you care alot about performance, and want a raw track day car. DO IT!

 

Awesome. That is pretty much what I was looking for. I have a 1983 RX7 that I'm building with an LT1 powerplant. I'll leave the track racing for that car and enjoy the mountains and curvy roads in the Corvette.

 

Good info, simple and to the point.

 

The reason for the noise with the single mass is at the bottom of this page where the guy asks:

"Q.) I was hoping you could answer this question I've asked many times and have never gotten a real answer: What is the cause of the noise from a ZF with the clutch out when it is changed to a single mass flywheel? So far everyone just tells me it does it without telling me why. If you could tell me or direct me somewhere I can find out, I'd very much appreciate it."

http://www.zfdoc.com/faq.htm

 

I had a "worn out" dual mass that I replaced with a single mass AL flywheel.

Idle noise in neutral (hot engine/tranny) is pretty much the SAME as with my bad DM. Some guys made comments at the last SOLO event, were worried I ate a bearing etc. So it's not that bad if you are already used to it. If you get a good DM flywheel, it will have a quiet idle, like its supposed to.

I have noticed a little less "grunt" from low rpm's, but this isn't like driving a new mini cooper, you don't have to rev it to start out any more than normal really.

Also, there is what I would describe as a "growl" at mid to low rpm's under moderate acceleration. Honestly, I think it sounds mean and cool. But I suppose it might bother someone.

The disadvantages, other than the noise at idle are the inability to really "bog" or load the engine at low rpm's. As in, if you want to cruise at low rpm's in high gear to conserve gas. 55mph you can not use 6th gear unless its level ground and your willing to feather the gas. I used to be able to lug the engine more with the DM flywheel and probably got overall better mileage on longer trips when I wanted to. So no cruise control in 6th gear at 55-60 anymore. 70+ is still fine for 6th.

If you are already used to the neutral idle noise, and never lug the engine, you may benefit from the performance advantage of a single mass flywheel. But, if you like to lug it and save gas every once in a while (its OK, I won't tell) or you can't stand the noise at idle, a new DM flywheel, like suggested is probably the way to go.