87 vette 81 big girl

Every dollar and penny extra you spend on a top notch racing clutch Is money well spent.

Mcloud, Centerforce, and Spec would be my choices.

I won't build a stick shift or manual trans engine for myself without a Billet steel or Billet aluminum flywheel and an explosion-blowproof racing bellhousing.

I blew apart a clutch and pressure plate hat in the past.

I left a 2 foot deep crater like the surface of the moon on the highway blacktop.

Aluminum GM bellhousing exlpoded apart and Mucnie 4-speed trans was on the ground too.

I was lucky, explosion went downward and not through the floorboard and cutting my feet, legs, and head off.

17 years old at the time and dumping the clutch at 7- 8 K in my old hotdrod Firebird.

My late friend was missing part of his right heel when the clutch and flywheel Both let go in his 1958 Corvette.
He did that back in 1959.
They managed to sew most of right heal back onto his foot.
But part of it was gone for good.

Exploding clutches and flywheels are like a huge bomb going off suddenly is the only way I can describe the experience.
Either you live or die.

Brian

93VettePilot

Good information. I still haven't had mine to the track. Mine is mostly for spirited street driving. I usually make about 1 trip to the track per year. Did any of your other clutches hold up to your racing habit? LOL

I used a street twin on my supercharged Trans Am. It was great at the track however not so much fun around town.

87 vette 81 big girl

I was only doing spirited driving too when my clutch blew apart.

My late friend sometimes told me a story back in 1970 when he had his 1969 L88 Big Block Corvette and a Street Race against a hot 426 Hemi Super Bee.

They launched off the line,
My friend banged each gear change at 7,000 RPM's.
He crossed the marked off finish line on the highway they had set.
As he coasted to a stop, he looked back in his rearview mirror.
No Hemi Super Bee was coming.
Only 2 distant headlights not moving.

So my friend drove back to see what was wrong with the other guy and why his engine possibly quit.

When he pulled up along side he saw a horrific scene...........

Blood was everywhere.

The rival racer had his head cut clean off his shoulders.

The opponents head was laying on the passenger floorboard.

Flywheel & clutch exploded on launch.
No Safety Steel Blowproof Bellhousing used by the other guy that summer night in 1970.

My late friend said he could not help to get sick.
And took some time to get over that gruesome scene he witnessed.

Take your chances with factory GM cast nodular iron single and daul mass flywheels and stock aluminum bellhousings spirited playing or racing.
Sooner or later you may experience the worst.

Brian

racebum

i think the biggest reason these work in so many cases is that the engine doesn't go over 6500 rpm and is only in the 6s for very brief periods of time.

i totally agree with all out race motors of any make any model. my rice rocket for example spins to 8700 with boost behind it and uses a billet chromoly flywheel

racebum

that's the problem with all of the crazy clutches. the more aggressive they get the worse they are around town. a kevlar clutch is a good way to split the difference as they aren't that much more aggressive than stock but hold a good deal more. it's hard to comment without knowing the power level or traction you have but many guys have been happy with the centerforce in that 350-400whp range. it's a bit spendy but easy to drive in town and won't slip dust off like the oem luk disc

87 vette 81 big girl

You are very wise and smart to use a billet steel flywheel.
8,700 rpm's is alot for any auto engine.

I have seen cast nodular iron flywheels come apart under 6k rpm's.

Happened to racers I knew.

There is tremendous stored energy in a rotating flywheel and clutch assembly at any rpm level above 2,000.

Kubs

UPDATE:

I took my old flywheel out and it looks pretty bad. I need to get it resurfaced, but if I cannot (due to it being dual mass) I am leaning toward the Camaro LT1 FW. For those that used it, did you also use the camaro clutch, or can it be used with the stock Vette clutch? Also, what is the exact amount needed to be machined off of it?

racebum

i thought you couldn't resurface a dual mass FW.

as the conversation has been going the LT1 flywheel will work but really should stay under 6500 rpm. above that the weight and inertia coupled with just not being designed to rev to the moon become a concern.

the single mass flywheel, camaro disc and corvette pressure plate combo is a solid one and it removes 20lbs of weight from the car. weight savings in many ways are more important than hp since weight not only increases speed performance, it also increases handling and braking.

87 vette 81 big girl

I am agreeing with you 100%,..........

But the danger still is present,
1st is the GM Nodular Iron cast construction single mass flywheel.
The cast iron material has molecule chains that are not as densely packed together as Billet steel or billet aluminum.

Cast iron if lightly nicked will easily fracture like a tungsten wheel cutting window glass.

Thermal stresses & vibrations will exponentially grow as engine RPM's increase.
Every material in the Universe and in a C4 Vette has a natural vibration frequency.

You experiment with your own car and use a cast iron flywheel with an aluminum bellhousing.............

Go out and do spirited driving, beat on it hard laying twin strips of rubber down on the blacktop.........

You may just find the natural frequency of your cast iron flywheel and clutch setup you are using.
At that point either may blow apart.

You can try and catch the broken parts moving around 500MPH to just under the speed of sound(700Mph or so) with your feet, body, & bare hands.

If you have a hydro formed 1/4" thick steel safety blowproof bellhousing from Mcleod or Lakewood, you will be OK.
Or a TRICK Titanium bellhousing will contain the explosion of metal fragments likewise.

Otherwise when the explosion does occur under the floor board of your Vette.........

You will find out if How much GOD does Love you or not in a fraction of a second.

He apparently loves me so I can warn everyone here on C4 nearly 30 years later to take flywheel & clutch failures and explosions CHIT seriously.

Unless you want do die that way.
Wife and friends finding you in your C4 Vette and your head decapitated off your shoulders and parts of you scattered 1000 feet around your Vette.

Brian

cv67

Time for dinner

87 vette 81 big girl

Time for a Beer too Ron.

Its Saturday night again on C4 tech.

93VettePilot

While you present some very valuable safety information, I have never heard of anyone breaking an LT1 single mass flywheel. I believe that GM has probably considered the possible liability and done its homework as far as flywheel/clutch failure. Also, modern day metallurgy has made leaps and bounds since 1970.

The problem with aftermarket billet flywheels is quality control. I bought a Spec Billet flywheel for my 97 Trans Am and the starter ring was misaligned during manufacture. I tryed shimming, shaving and everything else and starter would still grind and not disengage properly. Put the Gm flywheel back in and the starter works perfect. Well of course spec would blame my install procedure and not give me a new flywheel once it was used.

Spec has 0 customer service. And it will always be your fault if something goes wrong. I can't speak for the other aftermarket clutch manufacturers.

My point is that just because you buy an expensive billet flywheel and aftermarket clutch does not guarantee it will not fail. You should pick proven clutches and get plenty of feedback.

93VettePilot

Here are a couple of write up links. To answer your specific questions the exact amount is .090. You can reuse your old corvette clutch, pressure plate, and throw out bearing (assuming they are in good shape) but I highly recommend the sprung Camaro clutch disk be purchased. It will engage smoother and be less noisy. Also the new corvette pressure plate and throw out bearing would be cheap insurance to know that your clutch is in like new condition. Just keep in mind that mine is a 93 LT1. I'm not that familiar with the 90 corvettes so you may want to do some more research on your particular year model. And knowing what I know now I would never put a dual mass flywheel back in my corvette.

http://forums.corvetteforum.com/c4-t...sk-review.html

http://temp.corvetteforum.net/c4/nog...nversion.shtml

racebum

they did to a certain point. the flywheels were designed on an engine that revved to 5800 and can be pushed a bit past that. for drag racing or runs to 6500 i really can't see them being a problem.

if you road race a 7000+rpm engine pony up for billet chromoly or at a minimum aluminum

ps. i hate spec. they remind me of an expensive ricer clutch. just too many complaints from competent people with their products. their early clutches were horrible !

flywheel wise the fidanza fits well

i don't know of a quality billit for the c4, someone might make one though. i use exedy on the honda but they only make clutch products for the c5 or newer

87 vette 81 big girl

Hi,

GM HAD ONE MISSION ALWAYS.................
SAVE MONEY$$$$$$$$$$$$$$

Flywheel materiel construction included.
You have a cast nodular iron flywheel.

McCloude makes the best flywheels in the world.
Spec is just ok compared to McCloude.

I will teach you how to possibly blow apart your LT-1 flywheel.

I had a 1963 Corvette Fuel injected style Borg Warner 3 finger style 10.4" 327 clutch with 3,400 lbs holding pressure in my old Firebird behind a hot running sbc.
I had no problems for 3 months till one day it let go.
And let go it did.

Rev your LT-1 engine up to 7,500 rpm's with the clutch pedal held to the floor. Or gas pedal and clutch to the floor..............

Then dump the clutch fast in 1st gear.
Keep your foot planted firmly down on the gas. Don't let up.

Tap the clutch fast and grab 2nd gear.
Keep your foot on the gas.

Tap the clutch fast again & grab 3rd.
Foot on the gas.

Tap the clutch once again and grab 4th gear do not let up on the gas.

By now you should have done a 1/8 mile or half track burnout off the line like Arnie Beswick does before he races.

Grab Reverse and turn your head 180 and look out the back window.
Mash your gas pedal foot to the floor and steer with one hand.....

You should fly in reverse around 60-70 mph.
Its quite fun to do...........trust me I have done it for fun racing around town in Reverse racing my buddies.

Now launch your Vette off the line around 4,000RPMs, feather the gas and clutch so you get minimal wheel spin off the line.

Once you hookup mash your right foot to the floor and do not lift up even if you are going to die.

Make your 1-2, 2-3, 3-4 shifts around 7,500 RPM's.

Run that chit out of that sbc you built up for yourself to race.

Let me know if that factory GM nodular iron Lt-1 flywheel holds up for you or not & if the factory aluminum bellhousing contained the flywheel and clutch explosion for you too.

Brian

STL94LT1

Brian, is there an alternative to the LT1's magnesium bellhousing?

93VettePilot

How many people do you know on Corvette Forum that are shifting at 7500? The trick in hot rodding is to build a faster car and spend less money than the other guy.

About 90% of people on corvette forum are not hard core racers. People are looking for a little balance between street driving and track usage.

If I was going to build an all out race car that I trailered to the track it sure would not be on a corvette chassis. Too expensive to make it fast.

I don't think the Original Poster is looking for sub 10 second quarter miles. As he stated in his original post he is on a tight budget. Do you think he is really going to spend $800 on a racing clutch and flywheel.

BTW the bellhousing is made of magnesium.

87 vette 81 big girl

LOL

I do not know how many people do.

I was shifting at 7,500 - 8,000 RPM's in 1987 @ 17 years old.

And continue to do so in my 70-1/2 4-speed 462Ci Traditional Pontiac V8 engine TA.

Carburetors & Good Intake to match does not limit high RPM airflow like some EFI intakes.

Magnesium makes a very cool fire once you get it ignited.
I have done that for fun demonstrating to people with stripped down New Process GM transfer 4X4 cases that blew apart from GM trucks & SUV's.

Just need a blowtorch to get it going............then stand back and watch the fire.

Brian

Kubs

You are correct. I am on a very tight budget. Just trying to get this car running again.

I will not be shifting higher than 6500 RPM, and this is a road race engine not a drag engine so I will not be dumping the clutch repeatedly on launches.

Kubs

I must have missed this post last time through. Thanks for the links! I just replaced the clutch/pressure plate last spring so I know it is still good. Im not concerned about noise or engagement since this is a track only car.

Do you have a part number for the ARP bolts?