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Dual Mass Flywheel Weight

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Jun 20, 2002
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Tallahassee, FL
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none right now :(
Anyone know how much the stock dual mass flywheel weighs?

My clutch went out, and I bought a new aluminum Fidanza flywheel which weighs 13.5 pounds. I am not sure if it needs a new flywheel or not
(nothing is apart yet), so I am debating if the $400 is worth it if the current flywheel is ok.

I would prefer not to spend the money unless I either need to, or it will make a noticable difference. (especially considering that the morning the clutch went out, the power steering went too:( )
 

wx briefer

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Dec 24, 2002
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225
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Athens, Alabama
Corvette
LT4 - Cam, exhaust,intake / '03 Z06 caged/ '19 ZR1
What is wrong with the old flywheel? I simply knocked the glaze off of my OEM with a scotchbrite wheel and the new clutch works great! Don't machine the ole wheel because the cutting fluid at the machine shop will destroy the elastomeric membrane between the two parts and it will be really noisy! Just make sure the membrane is working OK and reinstall. The two pieces should move easily CW/CCW with hand pressure only but not wobbly!
 
Joined
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none right now :(
I blew the clutch, so the flywheel may be damaged. If it is, I will go with the new one for sure.... If it isn't, I am still considering the new one because of the benefits of a lighter flywheel (less load on the bearings, faster revving, more power to the wheels). The thing that gets me is no one seems to know what the stock flywheel weighs. I don't feel like spending a bunch of money to save 2 pounds, but if it is 10 pounds or more I may go for it.
 

FX GS

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Feb 24, 2001
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639
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Camp Hill, PA
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Formally Callaway SuperNatural Grand Sport #0001
The stock flywheel weighs 39 lbs. Therefore the lighter flywheel eliminates additional weight of rotating driveline mass.

This allows the engine to rev quicker, speeds shifts and helps to improve throttle response and the decreased mass helps to reduce driveline shock and the load on gearbox synchros.
 

wx briefer

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Joined
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Messages
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Location
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Corvette
LT4 - Cam, exhaust,intake / '03 Z06 caged/ '19 ZR1
The only real problem is the noise, as I understand it. Without the factory dual mass, the tranny sounds like a bucket of loose bolts rattling around. I read in a thread just a couple of days ago where a fellow forum member here took his lightweight out and put the original back in because of the noise.

At the track, it would not really be a problem. But on the street may be another issue for you. Really, though, it is not that much of a problem taking the transmission back out and replacing the flywheel if you don't like it. (you do have a lift and transmission jack?)
 
Joined
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Messages
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Corvette
none right now :(
no lift or tranny jack... this is one of the few jobs I won't be doing myself because I really have to get the car up in the air to do it right... I don't feel like using jack-stands for this one.

39 pounds Vs. 13.5 pounds is a huge difference... I will probably put the lightweight one in no matter what. I can't believe the aftermarket companies doen't advertise the stock weight... I was beginning to think the lightweight flywheels were not much different than stock, but 20+ pounds in rotation has to make a difference.
 

96CERon

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Sep 15, 2002
Messages
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Phoenix
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CE 1996
Just finished replacing the dual mass in my LT4. Had to take it up and down twice. Definitely not fun. So here are recommendations and results summary:
1. Bought the Stage 2 kit from Carolina Clutch--came with a stamped note on disc--flywheel side which was wrong--spring hub has to go with springs to the flywheel side. Also comes with a Valeo pressure plate that appears identical to the old unit. You need the spring hub disc because the original is a solid disc and you must have a spring hub disc since the dual mass provides this function normally.
2. Absolutely have the Fidanza match balanced to the old dual mass--find a good shop with latest balancing equipment--Windows based system. I learned this the hard way and had to take mine back out after initial install--terrible vibration above 3000. Found out that the external balance weight on my Fidanza was 30.5gms to heavy. This is many pounds at 3000 rpm. Also do not use the bolts and washers provided--order flywheel bolts with HARDENED washers from ARP (Summit).
3. Read the removal-install procedure from zfdoc.com and order the beam plates from him also. It is a real PITA trying to get at and hold the nuts on top of the drive shaft beam. The plates are also reported to improve stability on hard shifts--see zfdoc.com
4. Make sure that the fork ball is tight and the lock is also tight. Use ONE drop of blue lock tight on the lock only--my fork ball was unscrewing itself which is what got me into this to start with.
5. Drain and refill transmission with 10-60 Castrol from you local BMW dealer.
5. With everything back together after the match balancing, the results are: No vibration. Very slight amount of gear clatter at idle in neutral. Noticeable gear clatter/resonance of clutch hub springs(I think) between 1000 and 2000 with moderate to heavy acceleration but you can drive around this. Easier shifting. Faster acceleration by seat of the pants especially in lower gears and I only spent the price of a dual mass flywheel other than the 4 days taking it up and down twice. I did buy a transmission jack from Harbor Freight. Yes, the ligher flywheel is worth 300-400 pounds in virtual weight reduction in low gear and gets less as you go up in gears. Hope this helps.
 
Joined
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none right now :(
Thanks for the info.

My clutch went in yesterday, I don't have the car back as it also needs a slave cylinder and we are waiting on the part. The lightweight flywheel went in too, so hopefully there is some difference in performance.

The shop also fixed a leak on the tranny, and I had them put in Mobil 1. I am ready to have it back, I haven't driven it in almost 3 weeks!
 

96CERon

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CE 1996
In talking with zf.doc who rebuilds ZF's, he says that the ZFs he has rebuilt that used Mobil 1 had glazed synchros. The ZF web only recommends the GM oil or the Castrol 10-60.
 
Joined
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Messages
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Location
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Corvette
none right now :(
96CERon said:
In talking with zf.doc who rebuilds ZF's, he says that the ZFs he has rebuilt that used Mobil 1 had glazed synchros. The ZF web only recommends the GM oil or the Castrol 10-60.
I didn't see that on his web site... That is good info, thanks for sharing. I can change it again in a couple thousand miles and use the castrol 10-60. How much is it per quart?
 

96CERon

Active member
Joined
Sep 15, 2002
Messages
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Phoenix
Corvette
CE 1996
Vettelt193 said:
I didn't see that on his web site... That is good info, thanks for sharing. I can change it again in a couple thousand miles and use the castrol 10-60. How much is it per quart?

You will find the oil info on the actual ZF web site not zf.doc. List price is ~12/quart and you should be able to get it for ~$9--get 3 quarts.

Ron
 

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