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Discussion Starter #1
Never had anything but stock clutch on manuals-- Just wondering, are there any HD clutches that maintain factory-type engagement and pedal effort, or do HD clutches always come with a brutal leg-exercise that makes daily drivability a chore??? Thanks
 

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May I quote you on that?
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CMNT is the man to ask here. He has a SPEC stage 3 clutch after evaporating the factory clutch with 200 miles on the car.
 

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04bluegto said:
i was reading in corvette fever and they switched clutches on a Z06 to a spec 3 and a Fidenza lightweight flywheel and it weighed must unless and increased 10 hp. I planning to have that set up sooner or later.
very interesting. now i am interested as well. but i will probably wait a few years when a new clutch is a necessary replacement for maintenance.
 

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mistermike said:
CMNT is the man to ask here. He has a SPEC stage 3 clutch after evaporating the factory clutch with 200 miles on the car.
200? Try 85! :D

Anyway, yes, I have a SPEC Stage 3. The same SPEC stage 3 that I have behind the motor on my Camaro. The difference between the two being clutch discs. The one in the Camaro is a "hockey puck" style, I.E. multiple little friction pads around the circumference of the disk and the one in the GTO is a "Star" pattern. The SPEC unit uses a Valeo pressure plate and factory flywheel. Anytime a clutch is replaced on an LS1 vehicle, GM recommends replacing the flywheel and not resurfacing it.

What makes the difference on a SPEC State 3 is the springs used on the pressure plate and the disk itself. Factory Valeo pressure plates use 1,400lb or 1,800lb spring rates (I can never remember). This maintains the "user friendliness" and light clutch effort. However, you pay the price in maximum clamping force at high rpm as the pressure plate can't keep enough pressure on the disc, which allows it to float between it and the flywheel and as the load is decreased on the engine, it revs more freely spinning the disc with it, burning the disk and flywheel in the process, creating excessive heat, which in turn boils over the DOT 3 brake fluid used in the hydraulics and is essentially a domino effect.

You already have the ZO6 hydraulics in the car so this isn't a necessary evil to need changing. They did upgrade around 2000/2001 to the ZO6 unit in all Vette's and F-Body's but it still wasn't/isn't enough.

I would recommend a flush and fill to a DOT 4 semi-synthetic brake fluid (DO NOT GO FULL SYNTHETIC AS IT WILL EAT AWAY AT THE SEALS IN THE SYSTEM).

As to the flywheel, I would not go with a lightweight unit unless you plan to do a lot of drag racing and/or road racing where extended periods of high rpm are needed. For day to day driving and the occasional "races" and weekend trips to the drag strip, a heavier steel billet flywheel will help smooth rough engagments and disengagements out due to it's heavier rotating mass.

McLeod also makes an LS1 clutch (a twin disk setup), but I have yet to see it in a GTO and I do not have first hand experience with it, so I wish not to pontificate on it. :)
 

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...I would only use a Aluminum flywheel for roadracing. For launching and regular street engagement the steel one would be better. You will find yourself pushing the RPM more to keep everything spinning while trying to enage, also I believe its easy to glaze the flywheel while trying to slip it.
 

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Discussion Starter #8
Straight answer please, guys...

:confused: I'm not a mechanic, racer, or drivetrain engineer; when clutch goes, I would just buy it and my dealer would install it. You're telling me 'way more here than I needed to know. The original thread question was:

"Are there any HD clutches that maintain factory-type engagement and pedal effort, or do HD clutches always come with a brutal leg-exercise that makes daily drivability a chore???"

If a reasonable effort can't be had from a heavier aftermarket clutch, one that the wife would drive occasionally, then forget it. If there is a heavier clutch that doesn't necessarily require both feet, then I can worry about which one later, and the flywheel issues, etc. etc. At this point I just wanted to know if there is such an animal.........?????????
 

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I suspect even the lightest SPEC clutch would surpass the factory unit and offer similar pedal effort. Again, I defer to CMNT on this point. I remember years ago, a buddy of mine had a sick 13.2:1 Charger with a 3000 Lb Shieffer Triple-plate. It was all you could do to sit through a red light without leg cramps. I believe the SPEC units, other than an all-out drag race clutch, should be pretty civilized.
 

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I'm sorry to have gone into more detail than possibly needed.

But yes, anytime you run a higher spring rate, pedal effort will increase. DY can give the SPEC's specific spring rates, but they are high 2,000lb - low 3,000. That's a big jump from 1,400 - 1,800 from the factory. So figure your pedal effort in theory will nearly double. :D

It really isn't that bad though, I've been driving mine a lot in heavy Chicago traffic and my left leg is fine. But yes, it is notciably harder.
 

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1stChildhood said:
:confused: I'm not a mechanic, racer, or drivetrain engineer; when clutch goes, I would just buy it and my dealer would install it. You're telling me 'way more here than I needed to know. The original thread question was:

"Are there any HD clutches that maintain factory-type engagement and pedal effort, or do HD clutches always come with a brutal leg-exercise that makes daily drivability a chore???"

If a reasonable effort can't be had from a heavier aftermarket clutch, one that the wife would drive occasionally, then forget it. If there is a heavier clutch that doesn't necessarily require both feet, then I can worry about which one later, and the flywheel issues, etc. etc. At this point I just wanted to know if there is such an animal.........?????????

Thats the way I would go, but since I'm meeting all these guys who live close to me things might change!!
 

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Doing it yourself has a sense of satisfaction. :D

Actually, this car is the first one I didn't do the work myself on. :D The car was already at Speed for a for other "things" so I just let them deal with it.

Otherwise it isn't all that difficult, just time consuming.
 

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1stChildhood said:
:confused: I'm not a mechanic, racer, or drivetrain engineer; when clutch goes, I would just buy it and my dealer would install it. You're telling me 'way more here than I needed to know. The original thread question was:

"Are there any HD clutches that maintain factory-type engagement and pedal effort, or do HD clutches always come with a brutal leg-exercise that makes daily drivability a chore???"

If a reasonable effort can't be had from a heavier aftermarket clutch, one that the wife would drive occasionally, then forget it. If there is a heavier clutch that doesn't necessarily require both feet, then I can worry about which one later, and the flywheel issues, etc. etc. At this point I just wanted to know if there is such an animal.........?????????
The Centerforce is supposed to have more clamping force without heavier pedal feel due to centrifugal weights. I used one a long time ago on a car and liked it, but I think I have seen some bad press on this forum or somewhere.
 

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Yea, Centerforce hasn't had good LS1 clutches. Your only real choices are SPEC and McLeod. I would like to see someone install a McLeod twin disc into a GTO.
 

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McLeod

I had a dual disc 10 1/2 McLeod behind one of my Big Blocks. Definitely lower pedal pressure that the 11 inch HD it replaced. Nice and tight too, never fried the discs either lots of surface area, tons of grab.
 

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1stChildhood said:
Never had anything but stock clutch on manuals-- Just wondering, are there any HD clutches that maintain factory-type engagement and pedal effort, or do HD clutches always come with a brutal leg-exercise that makes daily drivability a chore??? Thanks
According to Spec, the Spec Stage 1 is very close in pedal feel to stock with enough clamping pressure increase to hold @ 425HP. The Spec Stage 2 holds up to @ 550HP, but you will need more pressure for the pedal. They claim a 15-20% increase in pedal pressure is needed. However, it is still not as hard as some of the older Centerforce and Hayes Clutches.

CMNT- Are you running the Billet Steel Spec Flywheel or OE?

Anybody running the Exedy Combo?
I had one request for it, but converted to Spec and saved $400-600.
 
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