hi guys,
i am looking at replacing my 40 lb old heavy duty dual mass flywheel from my 1991 vette/zf 6 speed with a lighter "fidanza" 15 lb i think it is !
has any one tried this flywheel?
i know that when replacing with this flywheel that there will be a bit of tranmission noise/rattle with the zf 6 spped box i got ,but the lighter weight of the flywheel will help it be more responsive,rev up faster e.c.t!
what are your comments if any?
who has the cheapest flywheel around and cheapest clutch kit?
thanks
glen
Australia

 

I have a SPEC aluminum flywheel, it weighed in at 13 pounds if I remember correctly. Yes it is louder, and if you have a black-tag ZF it will be even louder! If you have a blue-tag transmission it's quite a bit more tollerable.

Personally I like it, I've been driving with one for more than 50K miles.

As for the clutch, well, that really depends on how much power you're putting down. I went with a SPEC Stage 3+ clutch, and I really like it, but I needed something that held some pretty decent power. If your car is mostly stock I would think that a stock setup would probably be best.

 

If you go that route make damn sure the new flywheel is balanced against the old one. After I put in a fidanza I spent 1 year chasing an RPM specific vibration - went to fidanza several times - oh no - not our product - it was balanced correctly for your application!

To make along story short the POS was way out of spec - tough **** is fidanzas response - went to the lightweight steel setup - alls smooth now!

Carl Johansson

 

I have one and like it alright. I can definately feel the quicker revs!! It is REALLY NOISY in my zf. It could be my tranny but, man it is loud.

 

Here is some info. I did these 16 months ago—18K miles. I did all the work myself laying on the garage floor with a transmission jack from Harbor Freight. AND, I GOT TO DO IT TWICE. When I asked Carolina Clutches before I spent the $900 for the kit, they said that the flywheel and pressure plate were individually balanced and should go right in without a problem. There was a caution label on the flywheel that said you need to match balance the old one and new one, but assuming that Carolina knew what they were talking about, I ignored it-- Bill Boudreau at ZR51 Performance, says "these engines required post assembly balancing via variable weights added to the flywheel and some were very difficult to get balanced. Dave (Tech support at Fidanza) confirmed that you have to match balance his flywheel to the dual mass unit. He said that they build these with a nominal (mid point) balance job but if the original balancing was at either end of the spectrum you must match balance flywheel to the old dual mass flywheel. I really didn't enjoy taking it down again and getting it match balanced. Sure enough the balancing was off by 30 gms. This is a tremendous amount at RPM-->100 pounds. I had another problem, which was that the clutch disc from Carolina was miss-stamped as to which side is the flywheel side—I’m sure that this has been corrected. On a "regular" car the clutch disc springs stick out more to the transmission side, but with this conversion the springs go the flywheel side but unfortunately the part was metal stamped incorrectly. You can put the clutch assembly together wrong, but the transmission will not go all the way together because of the input shaft cover hitting the backward clutch disc. Another thing, when I took it back down to do the match balancing, I found that the flywheel bolts and washer provided by Carolina were of poor quality. i.e. the washer were soft and the bolts really had no shoulders near the heads and therefore the washers and holes in the aluminum flywheel where deformed as well as the area under the washers was concaved. This could be a long-term problem with the flywheel coming loose over time! You must use hardened washers and bolts from ARP actually Summit--I believe these are the numbers-- bolts 200-2807 for $15.99 and washers 200-8539 for $8. Call ARP and verify. I also used the beam plates from ZFDoc. It makes taking the beam up and down much easier. Also make sure you mark the drive shaft relationship to the rear axle yoke so you can put it back in the same position.

I have no drivability problem as reported by some. I take off just fine with no more issue than when it was stock. I can take off in second gear if I want to. It does have gear rattle in neutral at idle. The engine pulses cause the gears to clatter back and forth--goes away at higher idle speed. I just say--racing transmission! I also get a “growl-resonance” under heavy load--lugging from about 1K RPM to about 2K RPM--some say it is the resonance of the clutch springs--who knows, but whatever it is you can drive around it and there is no problem in 6th gear. I think a lot of the noise issue is the hard mounting of the transmission to the beam and to the rear axle. It is a great amplifier. I still think that the engine was not balanced very well to begin with and it still exhibits a little bit of imbalance. Do put in the 10-60 BMW oil in the transmission. It helps a little and is the best. I tried all different types of oils of differing weights etc. but to no avail.

Here is what theory says regarding the rotating weight reduction and resulting virtual weigh loss and rule of thumb horsepower increase and therefore faster acceleration. It is a function of overall gear ratio—i.e. this is for 3.54:1 rear axle ratio:

Gear 1 2 3 4 5 6
Mass Reduction in pounds 303 203 116 80 56 39
Equiv HP gain 30.3 20.3 11.6 8.0 5.6 3.9

Hope this helps.

 

hi ron,
thanks for the great info,help and write up!

so what sort of rpm/horse power range extra could i get from installing this fidanza light weight flywheel?

should i go and buy the fidanza alloy lightnened flyweel or go for a single mass lightened steel flywheel as far as not having too many problems?

how do you go about match balanceing from the old one to the new flywheel?

thanks,you provided so great knowledge and tips!
thank you
glen
Australia

 

The balancing trick is called "match balancing." It is done at the machine shop. IIRC, they put the two flywheels on a machine, 180* outta phase. It's much like a tire balance, but instead of going for zero, they go for the out of balance from the existing piece.

Now, I have the Fidenza. It is an ok piece, but for street use, it's just too damned light. It requires a bit of skill to launch and doesn't store any energy, to speak of, to help with said launch.

I don't advise them for street usage. I feel the lack of torque the lighter flywheel imparts.

If I was you, I would get a single mass flywheel from GM, the old Fbody part. It's about 22lbs, and is also even cheaper! It might be available in Oz without having to go deep, money wise. The only thing, it needs to be milled .090 INCHES (I don't want to get metric mixed into this mess!) so it will fit the space within the bell housing.

There is another thread here in Tech right now on just this subject.

 

Found the thread!

http://forums.corvetteforum.com/show....php?t=1588081

 

My 2 cents is to go with a single mass steel instead of the aluminum.

I've got a Mcleod clutch ($$$$) w/ steel flywheel and I'm glad I got the steel because it's hard enough to take off from a stop with it. It would be a nightmare with the aluminum.

I think the aluminum is 13-14 lbs and the steel is around 22 lbs.

I'm glad I got the steel and didn't want to go too light because I drag race so I need a little oomph getting out of the hole.

Now, if I road raced a lot I probably would have done aluminum.

 

hi there rukwkr,
can the steel flyweel still be machined down a little?
i guess once you machine down .090 to make it clear the bell housing it will make it weigh a little less?
is a little weight neccesary to keep the revs/speed up is it say like you mentioned "gettting out of the hole"?
any way cheers
glen

 

The F/W stores energy as a function of angular velocity (RPM) and mass. If the mass is reduced, you will have to launch at a higher RPM to compensate.

Look for driveability feedback from L98 guys with your gearing, and not just the LTx crowd. Should be some in the archives.

Also...you'll need a sprung hub disk with a single-mass F/W. You can't just run the stock setup. I've heard some good feedback on SPEC's 2+ clutch kit...I think they can be had for ~$460 direct from SPEC.

 

I e-mailed LuK with some questions about the new dual mass flywheel rebalancing and was contacted by a Dan ORIENT, although they are not distuibutors, he did provide the name of a company, which I dont know if I am allowed to say on the forum. I'm pretty sure I can use the company name dial-a-clutch cause I'v seen it here before, ordered from them for a different vehicle and the price was decent and delivery was in a timely manner, thru them, delivered, the stock flywheel/clutch package for a 89 vert was a bit over $1100.00. I dont know about Australia but the shipping is killer to Hawaii.

My 2cents worth

 

i agree.

1. quicker revs is true, but this is offset by more flaccid starts from a dead stop. this SUCKS on the street.

2. extremely LOUD can of rocks noise at idle with the clutch disengaged (black tag ZF). drove me crazy EVERY DAY.

the above are 2 huge reason why a C4 street application of the fidanza is a terrible choice.

JMHO.

 

I've had an alum flywheel, and now the stock dual mass flywheel in my vette, and I hated the alum. When I bought my car, it had already had an alum flywheel installed. I hated the box of rocks sound, and would often drive in 5th on the highway to not have to hear it. My friend has a LT4 as well, and he had the stock dual mass, and his was much quieter, and much easier to drive. It was alot easier to kill from a launch with the alum flywheel.

When I had the 396 put in, I bought a dual mass and had it put in as well. I know some people don't have to box of rocks sound, but for whatever reason, my tranny did, and I hated it. I won't go back to a lightweight flywheel.

 

hi again guys,
thank you very much for your helpful comments!
i will give fidanza alloy light flywheel a miss now!
but how about i buy a " f " body steel flywheel or buy a hays or centre force and fit that instead?
or may be slp like one of you mentioned?
they weigh around 22 lb which would be ok wouldnt/,as it is no near as light as 13lb!
" jegs" has a centreforce brand listed for corvette 89-96 6 speed,#183-700175/ 153 tooth for $360.00!
or could i get one cheaper like the slp one they have on sale might be the go?
any way cheers guys,you saved me a lot of noisy,power less jump start runs!
thnaks
glen
Australia

 

Looks like everyone else answered your question.

I didn't have to do any machining whatsoever but yes, my understanding is that virtually any "normal" flywheel (i.e. not a dual mass like we have stock) can be machined?

I get the "rocks in a can" noise occasionally but not often - this is with a blue tag ZF6, not a black tag like you have which is all the more reason to go with steel instead of aluminum.

 

People on this forum exaggerate about the aluminum flywheel noise and drivablitity issues. I have the Fidanza aluminum flywheel and Carolina Clutch stage III. At first when it was installed i had some problems with launching it, it took a little bit more finess then the stock DM flywheel was but you get use to it. Its a little noiser than stock but so is a single mass flywheel and if you let out the clutch with the car in Neutral you hear the rocks rolling around in the bellhousing noise but to tell you the truth that doesnt bother me because i rarely am in N with the clutch out so. Plus the drivetrain noise can easily be masked by turning up the radio or exhaust upgrades.

The advantages are:
it revs up sooo much quicker. I have no times to prove it but you can tell by driving it before and after.

 

hi there impala balko,
thanks for your input r.e fly wheel!
so would you reccomend the fidanza would you?
where and how much is the cheapest price you seen the fidanza flywheel sold for?
is your zf gear box a black tag or blue tag?
also how much for your clutch?
so how do you about lauching the clutch rite also when you take off and whats happens if you dont do it rite?
thanks
glen
Australia

 

you have a black tag. don't do it. do you enjoy your vette the way it is now? do yourself a favor and replace it with a new dual mass. the only real advantage -- if you care to care -- is faster revs. thats not worth it to me. it means almost nothing. you will not be happy. i can almost guarantee it. then you'll be wishing you had never done it, and end up ripping the lightweight out and spending twice as much. do yourself a favor and forget it altogether.

the whole lighweight thing is for racers, or people who think they are.

 

sxyvet,

I agree with balko. I have a Fidanza that I installed along with doing a ZF-6 Trans-plant on my 84over 2 years ago. I ditched the 4+3. And my ZF is a black tag. I hear people bitching about the "box of rocks" coming from the trans with the AL FW, but that can be minimized to nearly zero with tuning. Changing a FW has an effect on the tune. If you can hear the rattling, its because the tune is off. I can tell when my idle is right when I don't hear the trans rattling. That means all cylinders are firing and the AFR is right. As for losing low end, that's another myth IMO. I can't leave the hole at over 1200rpm without frying the tires and I have 11" ZR-1 wheels on the rear with Yokohama AVS Sports on them. And I'm using an SLP LT-1 Camaro clutch disc with sprung hub.