Before I buy a new flywheel..

[Regimof3]

Is anyone selling one of them fancy lightweight ones?

[Ccmano]

If you shop the internet you should be able to find a Fidanza light weight flywheel for about ~$375. Keep in mind that there is a high likelihood your transmission will rattle at idle with a single mass light weight flywheel. The degree of rattle varies from barely noticeable to loud and obnoxious. It’s luck of the draw as to how your particular trans will react. If you go this route I highly recommend you add a countershaft shim kit from Carolina clutch to minimize the rattle. The next time my trans is out I will be adding one. The rattle on mine leans towards the obnoxious side. Have fun...
H
:cheers:

https://www.carolinaclutch.com/product/corvette-c4-shim-kit

[32valvesftw]

Are there any Youtube videos that have recorded the rattle, it might be a good reference for people who don't have a full mod history on their car.

[Ccmano]

Are there any Youtube videos that have recorded the rattle, it might be a good reference for people who don't have a full mod history on their car.

Not that I am aware of. If you have it you’ll definitely notice it. You can instantly tell the difference between clutch in and clutch out. It’s more of a metallic clatter really. Makes you think there’s a serious issue with the trans. The shim kit is a simple install, other than having to remove your transmission. If I get a chance in the next week I’ll record mine and post it on YouTube. I should have my brake job done by week end.
H
:cheers:

[mpiecyk]

Has that shim kit been around for a while?

[Ccmano]

Has that shim kit been around for a while?

I suspect it’s relatively new. Not sure though. Had I known about it 2 years ago when I did my clutch and flywheel I would have installed it then.
H
:cheers:

[mpiecyk]

Now I'm interested, if it took away 50% of the noise and clatter I'll be very happy!!!

[Paul Workman]

Are there any Youtube videos that have recorded the rattle, it might be a good reference for people who don't have a full mod history on their car.

Well, yes. Try this one on a fully ported, stock cammed LT5.

508 HP LT5 (https://www.youtube.com/watch?v=y1YFa8ruh8A)

The temperature was in the 20s that day, which means the viscosity of the trans oil was maybe a bit higher than when hot (in spite of being synthetic oil). And, the idle has been bumped to 900 which helps. But, that said, Ami's Z has Pete's cams in it, and hot or cold it rattles like a box of rocks!

One thing else to be sure to do is use a spring'ed hub clutch disc (e.g., Centerforce 381039). That too will dampen trans rattle.

And, lastly, per Marc H. recommendation, the trans is loaded with Redline Heavy Shock Synthetic trans fluid which seems to be a little better than the Castrol TWS synthetic I was using (until it was discontinued).

[32valvesftw]

Thanks Paul.

[A26B]

A much discussed topic, a decision deserving of careful thought, a conversion involving considerable cost.

Transmission rattle is caused by impulse generated when a cylinder fires. It is absorbed by the DMF so long as the engine is essentially stock and in good tune. This goes for both early & late gear styles in the ZF transmission. The difference in gear styles, straight vs helical, becomes apparent when the conversion to a lightweight, SMF is made. Even the later style, helical gear design develops rattle, but to a lesser degree.

A light weight transmits more impulse to the transmission than a heavy flywheel. A heavier flywheel also makes street driving from a stop easier.

There are alternatives to making the giant leap from the stock DMF @ 37.5lbs to the Fidanza @ 13.5lbs.

Jerrys Gaskets makes an 18lb & a 22lb billet aluminum flywheel with a replaceable, steel clutch surface. Both flywheels have the same dimensions as the stock DMF. This feature maintains the same clutch geometry when using the stock pull-release clutch system.

https://www.jerrysgaskets.com/flywheel-jerrys-gaskets-18-single-mass-aluminum-billet-90-95-28c1/

https://www.jerrysgaskets.com/flywheel-jerrys-gaskets-22-single-mass-aluminum-billet-90-95-28c3/

The next obvious question is how much is the noise reduced when compared to the the extreme, lightweight flywheels, like the Fidanza and its counterparts. The answer is subjective and depends on the other variables, tune, cams, transmission gear style, etc.

There is no way to answer, except the lighter the flywheel, the more impulse transmitted to the transmission, i.e. more rattle.

In closing, "rattle" is at its greatest when the transmission is in neutral and the clutch is engaged (pedal released). Some drivers always shift to neutral & release the clutch pedal at stoplights....... other do not. If you do the former and it embarrasses you when others are nearby, then maybe you switch to the later.

There is always going to be some gain & some loss in the conversion. "Choose wisely grasshopper".

[XfireZ51]

I like the rattle at a stop light. Makes that 5.0 think there’s a junk C4 next to him.
😉🤣
The amount of rattle depends on the tune to a large extent. The more the engine pulses, the less rattle. I don’t have any rattle when driving. If it shows up its when trans is in neutral and clutch is disengaged.
I’m using the BMW trans fluid Steve Schroeder recommends and so far, I really like it.

[Paul Workman]

A much discussed topic, a decision deserving of careful thought, a conversion involving considerable cost.

Transmission rattle is caused by impulse generated when a cylinder fires. It is absorbed by the DMF so long as the engine is essentially stock and in good tune. This goes for both early & late gear styles in the ZF transmission. The difference in gear styles, straight vs helical, becomes apparent when the conversion to a lightweight, SMF is made. Even the later style, helical gear design develops rattle, but to a lesser degree.

A light weight transmits more impulse to the transmission than a heavy flywheel. A heavier flywheel also makes street driving from a stop easier.

There are alternatives to making the giant leap from the stock DMF @ 37.5lbs to the Fidanza @ 13.5lbs.

Jerrys Gaskets makes an 18lb & a 22lb billet aluminum flywheel with a replaceable, steel clutch surface. Both flywheels have the same dimensions as the stock DMF. This feature maintains the same clutch geometry when using the stock pull-release clutch system.

https://www.jerrysgaskets.com/flywheel-jerrys-gaskets-18-single-mass-aluminum-billet-90-95-28c1/

https://www.jerrysgaskets.com/flywheel-jerrys-gaskets-22-single-mass-aluminum-billet-90-95-28c3/

The next obvious question is how much is the noise reduced when compared to the the extreme, lightweight flywheels, like the Fidanza and its counterparts. The answer is subjective and depends on the other variables, tune, cams, transmission gear style, etc.

There is no way to answer, except the lighter the flywheel, the more impulse transmitted to the transmission, i.e. more rattle.

In closing, "rattle" is at its greatest when the transmission is in neutral and the clutch is engaged (pedal released). Some drivers always shift to neutral & release the clutch pedal at stoplights....... other do not. If you do the former and it embarrasses you when others are nearby, then maybe you switch to the later.

There is always going to be some gain & some loss in the conversion. "Choose wisely grasshopper".

Good to know 'bout the flywheels you have. Nooze 2 me!

[Vette73]

If you shop the internet you should be able to find a Fidanza light weight flywheel for about ~$375. Keep in mind that there is a high likelihood your transmission will rattle at idle with a single mass light weight flywheel. The degree of rattle varies from barely noticeable to loud and obnoxious. It’s luck of the draw as to how your particular trans will react. If you go this route I highly recommend you add a countershaft shim kit from Carolina clutch to minimize the rattle. The next time my trans is out I will be adding one. The rattle on mine leans towards the obnoxious side. Have fun...
H
:cheers:

https://www.carolinaclutch.com/product/corvette-c4-shim-kit


You mean fidanza flywheels rattle ? No.!!! Lol....I feel your pain, and mines cammed...Rattle away....

[Regimof3]

I know of the rattle. I've heard it. Not terribly bothered.

It seems Fidanza is the big name in the business so that's where I've been checking. I assume its a zr1 specific part? Like 1 from an lt4 won't fit an lt5?

[A26B]

I know of the rattle. I've heard it. Not terribly bothered.

It seems Fidanza is the big name in the business so that's where I've been checking. I assume its a zr1 specific part? Like 1 from an lt4 won't fit an lt5?

Flywheel for LT5 engine is specific, 8 flywheel bolts instead of 6 for LT1/4

[efnfast]

Flywheel for LT5 engine is specific, 8 flywheel bolts instead of 6 for LT1/4
On that note, last I knew Jerry was also carrying a flywheel for the LT5