Dual Mass FW Question
Thread Starter
Instructor
Joined: Nov 2000
Posts: 171
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From: Huntsville, AL
Dual Mass FW Question
Just finished pulling the tranny on my GS. After I removed the pressure plate and clutch, as I was inspecting the DM flywheel and noticed that I could turn, by hand, the part of the flywheel that is bolted to the pressure plate. Is the normal or is DM toasted?
Thanks,
Thanks,
Melting Slicks
Joined: Jun 1999
Posts: 2,872
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From: Wilmington NC
only a sucker will pay the money for a new clutch and dual mass from GM.. go with the mcleod twin disk for about a grand for everything including new master cylinder and be done with clutch issues forever!
Chris
Chris
Team Owner
Joined: Aug 2000
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From: San Pedro CA
I will put it this way... be cautious about what flywheel you do install.
the dual mass will do wonders for quiet with that ZF. Now, the 2nd gen ZF (Blue Tag) is much quieter than the Black Tag.
The steel flywheel that mcloed sells is much heavier than other SMFWs and the twin disk will add more weight, which will do wonders for street drivability.
I donno if I would replace the hydraulics. If yours are leaking, perhaps, but there have been so damned many problems with the replacements, would be a bit nervious.
If you go SM, then be sure to have the new flywheel match balanced to the DM. It will kill any chance of engine vibration. You see, the one piece rear main engines use the flywheel for final balancing.
oh, and to answer your question, the DM in your car is toast.
the dual mass will do wonders for quiet with that ZF. Now, the 2nd gen ZF (Blue Tag) is much quieter than the Black Tag.
The steel flywheel that mcloed sells is much heavier than other SMFWs and the twin disk will add more weight, which will do wonders for street drivability.
I donno if I would replace the hydraulics. If yours are leaking, perhaps, but there have been so damned many problems with the replacements, would be a bit nervious.
If you go SM, then be sure to have the new flywheel match balanced to the DM. It will kill any chance of engine vibration. You see, the one piece rear main engines use the flywheel for final balancing.
oh, and to answer your question, the DM in your car is toast.
Last edited by bogus; Mar 5, 2006 at 11:41 PM.
Burning Brakes
Joined: Sep 2003
Posts: 1,214
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From: Miami FL
The only thing I would add, is to see if you can find somebody that has replaced the dual mass set up and listen to their car and maybe have them take you for a drive. You are going to get plenty of folks who have done something other than OEM. My experience, I hated the noise. Maybe it was made worse by the Hotcam, but I went back and spent a small fortune to go back to the DM set up. Even with the cam I have little noise. I also have the black tag ZF...
Race Director
Joined: Feb 2001
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From: Manassas VA
NoVa Events Coordinator
St. Jude Donor '14
Sounds like the spring inside the DM is worn out. I would suggest contacting Bill aka ZFDOC (www.zfdoc.com). I bought a new DM from him a few years ago and the clucth kit. I think the total cost was around $1000.00
I have a street twin on my 383 engine. I think the DM is a little easier to drive.
I have a street twin on my 383 engine. I think the DM is a little easier to drive.
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Race Director
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From: Manassas VA
NoVa Events Coordinator
St. Jude Donor '14
no matter what you buy MAKE SURE the imbalance of the stock flywheel is copied to the NEW flywheel. If you go with a street twin or something other then a DM setup you will have to take it to a machine shop to have them balance the new flywheel to the imbalance of the old. LT1/LT4 engines are externally balanced.
You can order a street twin with a GM balance but if your flywheel has weight added then it’s not the standard GM balance. There are holes on the outer edge of the flywheel. If any of those are filled then you need to have the new flywheel balanced.
Buying a new DM flywheel would be easier because you can use DM flywheel weights in the corresponding locations from old to new. No need to take the flywheel to a machine shop.
KEEP THE OLD FLYWHEEL... incase you have a vibration issue you still have the original flywheel.
You can order a street twin with a GM balance but if your flywheel has weight added then it’s not the standard GM balance. There are holes on the outer edge of the flywheel. If any of those are filled then you need to have the new flywheel balanced.
Buying a new DM flywheel would be easier because you can use DM flywheel weights in the corresponding locations from old to new. No need to take the flywheel to a machine shop.
KEEP THE OLD FLYWHEEL... incase you have a vibration issue you still have the original flywheel.
Last edited by Bluewasp; Mar 6, 2006 at 06:24 AM.
Team Owner
Joined: Sep 2002
Posts: 22,209
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From: OBAMA IS HITLER
Originally Posted by TOO_HOTTVETTE
The only thing I would add, is to see if you can find somebody that has replaced the dual mass set up and listen to their car and maybe have them take you for a drive. You are going to get plenty of folks who have done something other than OEM. My experience, I hated the noise. Maybe it was made worse by the Hotcam, but I went back and spent a small fortune to go back to the DM set up. Even with the cam I have little noise. I also have the black tag ZF...
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
another thing, the DM does not have a spring, it has a rubber-like membrain that holds the masses together.
I have seen pics of these things taken apart. maybe other DMs use a spring, but the C4 DM uses a rubber membrain.
I have seen pics of these things taken apart. maybe other DMs use a spring, but the C4 DM uses a rubber membrain.
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Originally Posted by bogus
another thing, the DM does not have a spring, it has a rubber-like membrain that holds the masses together.
I have seen pics of these things taken apart. maybe other DMs use a spring, but the C4 DM uses a rubber membrain.
I have seen pics of these things taken apart. maybe other DMs use a spring, but the C4 DM uses a rubber membrain.
I took apart my 89's DM.
It has a spring and metal flange. No rubber membrane.
Last edited by pablocruise; Mar 6, 2006 at 05:13 PM.
Race Director
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From: Manassas VA
NoVa Events Coordinator
St. Jude Donor '14
Originally Posted by 89 Paul in Cal
Wrong.
I took apart my 89's DM.
It has a spring and metal flange. No rubber membrane.
I took apart my 89's DM.
It has a spring and metal flange. No rubber membrane.
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
Originally Posted by 89 Paul in Cal
Wrong.
I took apart my 89's DM.
It has a spring and metal flange. No rubber membrane.
I took apart my 89's DM.
It has a spring and metal flange. No rubber membrane.
I have seen that pic before.... alone, tho... maybe not provided by you, but someone has presented one very much like that.
Which explains entirely why I have a screwed up perspective on this subject.
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
The outer flywheel should turn, it is normal. If you read the service manual there is a test to determine if the internal FW damper is bad. I can't remember the specs right now but when I get home I can post the procedure.
Pro
Joined: Sep 2000
Posts: 599
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From: Tampa,FL
DJ, don't forget about callaway corvettes. They offer a custom nodular iron SM flywheel balanced per GM spec and a dual friction CF clutch kit. The clutch kit is nothing abnormal BUT the SM flywheel is something that made me lean their way. It weighs more than the AW but less then the OEM DM. Approx 19lbs which I feel is a great compromise. And yes it can be turned. I just bought a kit from them and will install shortly. Would be glad to share the info when done. By the way, I got the idea from one of the boys off the GSR 
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
The 2nd pic.....you mean the Reeses's peanut butter cup wrapper looking thing (LOL)?
That is the thin metal flange I was talking about. It interlocks with that torque limiter's notches(#4 in illustration).
In the channel where the spring resides is a thin film of lubricant.
Not runny fluid oil, but not thick heavy grease either.
That is the thin metal flange I was talking about. It interlocks with that torque limiter's notches(#4 in illustration).
In the channel where the spring resides is a thin film of lubricant.
Not runny fluid oil, but not thick heavy grease either.
Last edited by pablocruise; Mar 6, 2006 at 10:11 PM.