Yoko-Chan

Hello again friends,
I've decided I'm going to change my clutch as I already have my transmission out and completely apart, and I was wondering if a lighter weight fly wheel would be a good upgrade. I daily this car but also frequently hit the canyons and track at I'd say an 80-90% driving intensity and I've been told a couple times by non Corvette people that I should buy a light weight fly wheel. I'd love to hear your opinions on the idea and any experiences shared.

thanks for your time and I hope you gave good luck!
- Will

Lawandorder

I’ve read that light weight flywheels are for track only

Tron Z

As near as I can tell, the Spec Corvette guys prefer to upgrade to the twin disk LS7 clutch for greater reliability. Since it has two disks, the LS7 clutch assembly is meaningfully heavier than the OE counterpart. The Spec Corvette rules allow a lightweight flywheel when upgrading to the dual disk clutch. The weight difference of the OE clutch and flywheel compared to the LS7 clutch and lightweight flywheel is virtually nil.

If I was so serious about drag racing that I felt that I needed a lightweight flywheel to be competitive, I would change to a different car. AFAIK, there still isn't an off the shelf, readily available blow-proof bellhousing available for the C5.

Some background:
A friend of mine had a clutch blow apart. It came up through the tunnel, through the dash and exited the car through the windshield, taking a chunk of his right foot with it. The car literally looked like a hand grenade went off in the interior. If you are that serious about drag racing that you "need" a lightweight flywheel to be competitive, please think long and hard about the safety implications of doing it in a C5 with its balsa wood floor. At the very least, you might consider a SFI rated flywheel and wrapping a transmission blanket around the bellhousing ... though admittedly, it wouldn't be nearly as effective as a blow-proof bellhousing.

If, like me, you enjoy being able to walk around under your own power, pleas take a minute to consider the second order consequences of what you are contemplating.

Johnny Hardcore

I’ve run a lightweight 14lb Fidanza flywheel in my coupe since 2007. I’m a big fan of the quick revs for spirited driving. At the drag strip and attempting good launches it did take some getting used to at first. The rpm window for good launches moves up a few hundred rpm’s. So you’ll need to adjust for this. But once rolling there is no comparison on the lighter weight wheel being more advantageous in deceleration into turns and quicker to rev when accelerating out.
I would never go back to a heavy steel/ OEM weight flywheel in my C5 ever again.

With a cam on the higher side of mild NA I did prefer the 4.10 gear with the lighter flywheel. Having both the cam and lighter wheel the low speed parking lot driving takes a bit of fineness. And my tunes have been spot on. So again, similar to changing your launch technique the low speed creeping will also require a driver adjustment to keep it smooth. Of course dropping a gear in like 4.10 or 3.90 will help with this. I’m in a 3.42 again and I’m not a fan of the gear for a few reasons, one of which is the light flywheel. Frankly I just hate how long 3.42s are. But with 568rwtq/634whp I’ve decided not to go back to a 4.10. So I’ve got a 3.90 diff awaiting a rebuild whenever I get around to it. It’s all part of the puzzle.

My vote is for the lightweight flywheel. Just know you’ll have to adjust your low speed parking lot driving and launch techniques with one compared to how “lazy” you can be with the stock weight flywheel, which compensates for lack of driver technique, during these activities. Other than that a lightweight flywheel is better for performance in every way.

Give this article a read. The test cars are Fords but the flywheel comparisons are what you’re learning about. Courtesy of forum member lionelhutz some 10yrs ago.


http://www.uucmotorwerks.com/flywheel/LWF_DRAG_TEST.pdf

JHrinsin

The factory C6 LS3/LS7 clutch is a fairly heavy single disc setup. The factory C6 ZR1 LS9 clutch is a twin disc setup.

If you read the Spec Corvette rules they state this; "OEM (C5) LS6 clutch with factory steel flywheel is allowed. (C6) LS7 factory clutch with RAM Clutches 19lb aluminum flywheel is allowed to improve clutch reliability and bring overall unit weight back down to (C5) LS6 level." So the flywheel choice really depends on the pressure plate / disc that you are using. If you have gone with the "better, but heavier" C6 factory LS3/LS7 clutch for example, but want to make it more responsive and not be a PITA to drive in city traffic, than a lighter weigh aluminum C6 flywheel from say Ram or Fidanza would be a good match.

Please note that the flywheel has to match the pressure plate. The C5 and C6 components themselves are are not interchangeable - in other words you can NOT use say use a LS3/LS7 pressure plate on a LS1/LS6 flywheel and vise versa. But you can bolt-up the whole C6 flywheel / pressure plate clutch as an complete assembly on a C5 LS1/LS6 engine.

Kubs

I use a Fidanza aluminum flywheel and a stock Luk clutch/pressure plate. It drives close to stock but is like 12-14lbs lighter. I drive it on the street all the time without issues.

Yoko-Chan

that might be a good compromise, if it’s not too expensive I might get it. I’ll look into that today.

JHrinsin

That's because you're a third generation Corvette racer Mike!

LowcountryVette

Yes, go lightweight. You will like it.

Stroker_9

I have the Monster light weight flywheel option with my Monster LT1-S twin disk and its great.

heggsc5

I chose to stay with a heavier flywheel when I had my Monster LT1-S installed according to a lot of opinions/advice when doing research. If I could do it again, I would probably go with the lighter option. I like the idea of a quicker/snappier rev match blip for street driving, but I guess that also means a shorter window of time as revs drop too. Blips did feel heavier/slower after the blower install though, I don't exactly remember what they felt like n/a to be fair. I think I believe you said you're a canyon carver in prev posts, so I would tend to think you'd like a lighter flywheel, but that's just my two cents.

spfautsch

I just pulled a lightweight (15 lbs) flywheel coupled with a metallic button friction disk out of mine (a remnant of a previous owner). The combination made the car incredibly difficult to take off from a stop without making me look like I was still learning how to drive a manual. For most applications I would not recommend that combination.

Depending on what you want to do with the car, I think a lightweight flywheel might be ok if coupled with an organic friction disk for street use. Anything else is track only.

I went back with a stock single disk LS7 clutch kit (pressure plate, friction disk and cast-iron flywheel). I can tell a slight difference in how fast it rev matches when downshifting. Aside from that it's so much easier to drive I could give a **** less. If I want to drive something that reminds me of being in a racecar, I have a 530 rwhp C4 to call on.

Another consideration is longevity. Ligther flywheels come at a price, driveability and longevity are key among them. If it was a 4 hour job to replace the clutch that would be far less of a detractor. But that's not the case. This is what the engine side of my lightweight flywheel looked like.

full res here

Those burn marks are "cooked" all the way through the metal, and it's certainly compromised the metallurgic integrity of the flywheel. Choose your flywheel / clutch package accordingly.

HeyFred

I installed a 18lb flywheel with monster single disc on my LS6. No driveabilty issues.
Car accelerates like a rocket. 2 thumbs up here.
Don't go lighter than 18lbs. A lower weight is when driveability comes into play

JHrinsin

The factory stock LS3/LS7 clutch assemblies (flywheel, pressure plate and disc) weigh approximately 8 lbs more than the factory stock LS1 or LS6 clutch assemblies. The LS3/LS7 factory flywheel itself weighs about 26-27 lbs while the Ram aluminum flywheel weighs about 18-19 lbs and the Fidanza aluminum LS3/LS7 flywheel weighs in around 13-14 lbs. There are other options out there of course. It all depends on how big of a camshaft you have and where you are driving your C5 as well as the the "manners" that you are willing to deal with.

Supercharged111

I did a Spec Stage1 10.5" aluminum flywheel and pressure plate. Dropped 20# and since it's a Stage1 it's not super grabby. This has been a street only car for many years. I love it and I don't dream of going back to something heavier. The car pulls a lot harder in the first 3 gears. It was like doing headers a 2nd time.
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