Cal Club Autocross Forums

Well as happens to us all (I've been told) my Dual Mass Flywheel is giving up the ghost. At 120K miles I can't complain. I plan to run it this weekend, but want to replace it before the divisionals well I have the car down for new injectors.

The dual mass is no longer produced or available. Not a problem there are a number of single flywheel replacements. This is looking for the opinion of former C4 racers. My mechanic likes a a package from Summit, that can take more horespower than I would ever put in the car if I do a rebuild, but my concern is the aluminum flywheel. I like a different package with a steel flywheel, however the manufacture of that kit even recommends the aluminum flywheel for autocross application. The steel will be noiser than stock, I have been told the alminum will be even more so. The two kits are listed, both cost about the same. Thanks for the opinion.

http://www.summitracing.com/search/Bran ... toview=SKU" onclick="window.open(this.href);return false;
Clutches built specifically for your Corvette.

These RAM single disc push-type conversion C4 Corvette clutch kits are designed to replace the pull-style clutch and dual mass flywheel in your factory 1989-96 C4 Chevrolet Corvette. They consist of an aluminum flywheel, a high-clamp Borg and Beck-style pressure plate with a 2,800 lb. clamp load, and a RAM 300 Series organic clutch disc. The RAM single disc push-type conversion C4 Corvette clutch kits use an internal hydraulic throwout bearing, replacing the factory release mechanism, to complete the install. Best of all, these clutch kits are capable of handling up to a 700 hp holding capacity. $889.95

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C4 Corvette Clutch Kit And Flywheel Package C4 Corvette Clutch Kit And Flywheel Package

This Kit Fits 89-93 L98 And Lt1 Corvette. The Kit Includes A Complete Sprung Hub Street Performance Clutch Kit And Billet Steel 1 Piece Flywheel. Weight 60lbs
Manufacturer: Carolina Clutch
SKU: 111077 Part No: 04-113/1S
Clutch Kit : Stock Replacement Clutch Kit C4 Corvette Clutch Kit And Flywheel Package
This Kit Fits 89-93 L98 And Lt1 Corvette. The Kit Includes A Complete Sprung Hub Street Performance Clutch Kit And Billet Steel 1 Piece Flywheel. Manufacturer: Carolina Clutch
SKU: 111077 Part No: 04-113/1S List Price: $995.00 EA, Your Price: $850.00 EA

Since the original dual mass flywheel is no longer available, Carolina Clutch is recommending the 1 piece billet steel flywheel and sprung hub street kit as the best option for the owners who preferred the original dual mass flywheel and clutch kit. This setup will drive and feel like the stock setup that was original in the car however you may hear some gear noise that the dual mass was covering up but this is a much quieter option than the aluminum flywheel which will tend to amplify the noise. However they did send me an e-mail if the car is more for Autocross than HPDE there aluminum flywheel would be prefered and is 16lbs lighter.

Thoughts? Price is the same, but my mechanic is primarily a Mercedes (where I met him, VW, Porsche guy).

I assume you have no intentions of running in the stock class... Because this will move you to BSP if you are not already there.

You would be nuts not do to go aluminum. The dual-mass setup is a boat anchor, this swap makes a huge difference in a C4. And any flywheel change from dual to single mass will increase noise, regardless of the material. But it is really only bad at idle in neutral, your trans will sound like a box of rocks has been poured inside.

Also, SP rules do not allow you to change the type of slave, push to pull etc. So you should look for a direct replacement that uses an OE style bearing. With an L98 you don't need anywhere near 700hp of clamping force, something street-able will do.

http://www.specclutch.com/cars/Chevy/Co ... 989/Single" onclick="window.open(this.href);return false;

Isley, thanks for the heads up on the rules. I am running BSP. Didn't realize the throwout would make a difference. My mechanic knows that my likely intention when the motor needs a rebuild will be to bore and stroke it to a 383, with a target of 400hp at the rear wheels. Hopefully not anytime soon.

Jason ... we're probably getting fairly close to having to put a new clutch into the Miata. I've had a number of people tell me to go with a "lightweight" billet steel flywheel and to avoid aluminum ... and we won't be running much power. Yet you feel aluminum would be OK for a built C4 engine? I'm guessing there are aluminum fly wheels and then there are high end Aluminum racing Flywheels ?

Mako Koiwai wrote:Jason ... we're probably getting fairly close to having to put a new clutch into the Miata. I've had a number of people tell me to go with a "lightweight" billet steel flywheel and to avoid aluminum ... and we won't be running much power. Yet you feel aluminum would be OK for a built C4 engine? I'm guessing there are aluminum fly wheels and then there are high end Aluminum racing Flywheels ?

Everything should have an aluminum flywheel. *OK, some turbo cars seem to like a heavy flywheel to keep the engine spooled, but they have enough power to overcome the weight.

The fact that you "wont be running much power" makes it even more valuable. People drop thousands to shed a few lbs off of the flywheel you have at each corner of the car (wheels), don't ignore the important one.

These seem to be very popular with the FP/EP Miata guys: http://www.10000rpm.com/index.php?optio ... &Itemid=75" onclick="window.open(this.href);return false;

A little more street friendly: http://www.specclutch.com/cars/Mazda/MX ... 999/Single" onclick="window.open(this.href);return false;

Jason Isley BS RX8 wrote:

Mako Koiwai wrote:Jason ... we're probably getting fairly close to having to put a new clutch into the Miata. I've had a number of people tell me to go with a "lightweight" billet steel flywheel and to avoid aluminum ... and we won't be running much power. Yet you feel aluminum would be OK for a built C4 engine? I'm guessing there are aluminum fly wheels and then there are high end Aluminum racing Flywheels ?

Everything should have an aluminum flywheel. *OK, some turbo cars seem to like a heavy flywheel to keep the engine spooled, but they have enough power to overcome the weight.

The fact that you "wont be running much power" makes it even more valuable. People drop thousands to shed a few lbs off of the flywheel you have at each corner of the car (wheels), don't ignore the important one.

These seem to be very popular with the FP/EP Miata guys: http://www.10000rpm.com/index.php?optio ... &Itemid=75" onclick="window.open(this.href);return false;

A little more street friendly: http://www.specclutch.com/cars/Mazda/MX ... 999/Single" onclick="window.open(this.href);return false;

I wouldn't say my Corvette is short of power? Especially not short of Torque.

Arthur - Sorry 4 the hijack

Mako Koiwai wrote:Arthur - Sorry 4 the hijack

No problem, I'm easy.

For those who might care, I decided to go with good street manners over absolute performance. I have selected a Spec Stage 2+ clutch kit, and Spec billet steel flywheel. They claim to be machined to a tolerance of .001, well see if this is the case. The stage 2+ is supposed to give me a clutch I can manipulate beyond just an on off switch. This is important to me when parking on the hill infort of my house and other street uses.