Spec stage 2 clutch question

[N20LT4Bird]

My buddy came over and drove the car. Well sort of. He let the clutch out, rolled it about a foot and stopped. He said he thought it was the flywheel too. So all of ya'll and him made me go ahead and order a new flywheel. Looks like another fun weekend.

Sucks. But, ive been there. Ive had the tranny out of my car so many times, I lost count! Ive got the whole process down to about an hour and half to two hours turn around! Just get a good used flywheel, make sure its flat with a machinist's straight edge and take some emery cloth to it. You want to move the emery cloth in back and forth motion around the cirumference of the flywheel. No little circles. Ive got the stage three in my car and it doesnt do what your reporting.....and thats an emery clothed flywheel - never been turned. Good luck.

[fastTa]

Anyway, I can't recommend using an aluminum flywheel if you expect to keep this as a daily driver. You lose torque with an aluminum flywheel, and torque is what helps us kill the ricers out of the hole.

Well.....the lighter weight of the aluminum flywheel cannot create a loss of torque. It just feels that way because you have less inertia of mass transfer with the lighter aluminum.

The aluminum flywheel will make those hardcore launches a little softer, but once you get the motor wound up and start rowing the gears, the aluminum flywheel will actually put more power to the ground. This is due to less power being soaked up, and it allows the rotating assembly to spin much quicker and thus allow the motor into the powerband much quicker.

It is a debatable tradeoff, but on the street the aluminum flywheel is incredibly better and much more fun to drive!

[MN6WS6]

Actually, Kevin, it is a loss of torque at the rear wheels, and that's where you feel it. You lose torque and gain horsepower with an aluminum flywheel.

[fastTa]

Actually, Kevin, it is a loss of torque at the rear wheels, and that's where you feel it. You lose torque and gain horsepower with an aluminum flywheel.

The only way to reduce the specific torque output of a motor is to change something on the motor itself. The only way. Think about it. Sometimes on dyno graphs, you will see a slightly different curve at the beginning because of the reduce inertia of mass (especially on load capable dynos such as the SuperFlow), but the overall curve, power under the curve, and peak torque numbers will not be adversely affected. Different gear ratios can show slightly different torque curves as well, but this is just beacause of the nature in which a dynamometer measures wheel horsepower. It just takes slightly longer for the drums to be accelerated when the driver first squeezes the loud petal because there is less spinning mass to help overcome drivetrain loss.

[MN6WS6]

If all that were true, then why do 18 wheeler flywheels weigh as much as they do? They have to have the torque multiplication (if you'll call it that) of the heavy flywheel to "sling" the tranny gears around and get the truck moving. RWTQ numbers are decreased with an aluminum flywheel, I've seen it myself, and some websites even tell you that in advance. Now your argument is true, if the engine were on an engine dyno, but on a wheel dyno, the numbers do change.

[fastTa]

If all that were true, then why do 18 wheeler flywheels weigh as much as they do? They have to have the torque multiplication (if you'll call it that) of the heavy flywheel to "sling" the tranny gears around and get the truck moving. RWTQ numbers are decreased with an aluminum flywheel, I've seen it myself, and some websites even tell you that in advance. Now your argument is true, if the engine were on an engine dyno, but on a wheel dyno, the numbers do change.

The reason an 18 wheeler flywheel is so large is for the very reason I pointed out before. 18 wheelers can carry loads in excess of 100,000 lbs. Whether it has 9 or 18 gears, that tractor has to overcome the load weight + the trailer weight + the tractor weight + the drivetrain rotating mass from a dead stop or even up a hill. This is alot on a tractor-trailer. So having a very heavy flywheel helps to reduce in lugging the diesel by providing assistance through inertia of mass. The additional rotating mass of the heavy flywheel that is spun by the diesel from a stop sign helps to provide more efficient kinetic energy transfer from the crank to the drivetrain. The heavier the flywheel, the more torque it takes to get it spinning. Simple physics.

It is all about torque multiplication in regards to performance and not the peak overall torque potential that you seek to prove. Sure you can take a 500 lb flywheel and spin it up to 6,500 RPM's with a stock LS1 motor and then measure the peak torque potential by that particular flywheel. It would prove to show massive amounts of torque potential, but then would prove to simulataneously be obviously devastating to the performance of the LS1 car.

Less drivetrain roating mass, less driveline angle, and better ring and pinion relationship equals more power to the ground.

[Jeff_in_Atl]

Update on clutch woes.

I put in a Centerforce flywheel this weekend. The vibration is a little better but it's by no means gone. It still chatters on start and stops. It's worse in reverse. A little during shifts depending on fast your trying to shift. I wish I had gone with the Spec stage 1 clutch instead of the stage 2. I'll give it a couple of months and if it isn't better by spring time, I'm putting in an organic disc.

[Joe 1320]

I put in a Centerforce flywheel this weekend. The vibration is a little better but it's by no means gone. It still chatters on start and stops. It's worse in reverse. A little during shifts depending on fast your trying to shift. I wish I had gone with the Spec stage 1 clutch instead of the stage 2. I'll give it a couple of months and if it isn't better by spring time, I'm putting in an organic disc.

I wish I could test drive it and feel what it's doing. It makes me wonder if there is enough pressure to hold the disc down properly. The Spec clutch is more aggressive, but a stage 2 shouldn't chatter. Any worse when you get some heat in it?

[Jeff_in_Atl]

I wish I could test drive it and feel what it's doing. It makes me wonder if there is enough pressure to hold the disc down properly. The Spec clutch is more aggressive, but a stage 2 shouldn't chatter. Any worse when you get some heat in it?

It's not slipping at all. As a matter of fact, I stalled it twice. I haven't stalled a clutch car in 15 years.

I haven't notice any difference when it might be warm or cold.

I think the pressure plate is not parallel to the flywheel. I got mad at it before I ripped it apart and rode the clutch with the emergency brake on trying to wear the high spot off. It left a colored mark on the flywheel and pressure plate. It's only in 1 spot. It should have gotten hot all the around it. This tells me the pressure plate surface is not parallel to the flywheel surface.

I'm going to drive it for a while and see how it does. I'm tired of working on it. I have an addition to my home that I am trying to work on. It's a 750 sq foot master suite. A 15'X 27' bedroom, 10'X 10' closet with a 4' sky light, a 5'X 10' utility room extension, and a 17' long bathroom with 2 4' long skylights, corner tub, and a 7'X 7' walk in shower. Everything has vaulted ceilings. It's been keeping me busy.

[MN6WS6]

I'd call Spec and let them know what's going on and how much trouble you've been through trying to fix this problem. They may send you a replacement as long as you send yours back after you fix your car. Those guys up there are really nice, and it wouldn't hurt anything to try.

I know how you feel on the stalling the car thing. I did the same thing when I put mine in. I've had a couple of people drive my car and buy Spec II because of how tough it feels when it grabs. All of us run nitrous cars and have had zero problems with our clutches so far.

[Joe 1320]

I think the pressure plate is not parallel to the flywheel. I got mad at it before I ripped it apart and rode the clutch with the emergency brake on trying to wear the high spot off. It left a colored mark on the flywheel and pressure plate. It's only in 1 spot. It should have gotten hot all the around it. This tells me the pressure plate surface is not parallel to the flywheel surface.

.

Ahh.... that could very well be the case. I was going to ask if you were sure the PP was mated perfectly parallel the first time around but figured you would have noticed that. Stalling could be considered normal when getting used to it, the chatter or vibration isn't. That in reality, could be due to the lack of even pressure due to improper alignment. Sux broh...... I hate taking stuff apart multiple times.

[Jeff_in_Atl]

Well to add insult to injury, I pull out on PIB just now and floor it. It gets up to about 3500 RPM and starts vibrating. Same vibration in all gears over about 3500 RPMs. So I pulled into a parking space, put it in neutral and rev it up with the clutch in. Around 3500 RPMs it starts vibrating. It' vibrates through the red line. It feels like the new flywheel is not balanced correctly. You know I don't expect to get crappy parts when I pay $500 for a clutch and pressure plate and $350 for a flywheel. This is ridiculous. I got the good stuff too. If I don't fix it, it will probably take out the crank bearings. If I could afford it, I'd trade it.

[Jeff_in_Atl]

Update

I sent Centerforce an e-mail about the flywheel. This is the response I got back from them. I thought LT1s were internally balanced. Why would the flywheel/flex plate have to be balanced to the crank?

In reply to your e-mail, Our flywheel's and clutch assemblies are
balanced to a detroit specification. If you are experiencing a engine
vibration/out of balance condition, (not a motion vibration), the only
proper way to convert a LT1 engine from a automatic to a stick shift
vehicle is, match the balance of the flex plate from the engine and
duplicate this balance into the flywheel being installed onto the
engine. Originally LT1 camaro/firebird vehicle equipped with a stick
shift had a X or yellow paint dab on the flywheel which required the
yellow mark from the pressure to be aligned to the balancing mark
provided on the flywheel the proper balancing, being you converted this
vehicle from a automatic to stick shift, you have no reference mark with
our aftermarket flywheel, thus being possible cause of vibration.

[pete]

Well there ja go! All you have to do is pull the tranny, pull the flywheel... rotate one bolt hole to the left and reassemble. Try it out. Repeat as necessary. Or go back to the automatic.

Things to do in your spare time.

[Jeff_in_Atl]

Well there ja go! All you have to do is pull the tranny, pull the flywheel... rotate one bolt hole to the left and reassemble. Try it out. Repeat as necessary. Or go back to the automatic.

Things to do in your spare time.

LOL.

I re-read his e-mail and I found a hole in it. I haven't sent it yet but here is my reply.


If that were the case, then pretend my car was originally a 6 speed car. It would have the mark on the flywheel. If I replaced it with a Centerforce, your flywheel doesn't have a mark to line up with the existing pressure plate. OK so I could set the 2 flywheels on top of each other and transfer the mark. But what if I used your flywheel and pressure plate. The pressure plate doesn't have a mark to line up either. You can't transfer the mark because you can index it 120 and 240 degrees and it will bolt on the flywheel. It is not keyed to only go on 1 way. It is neutral balanced.

The LT1 engine is an internally balanced engine. We both know that means it requires no external counterweights to balance it. That means the flywheel/flex plate are neutral balanced also. They have weights to make them neutral. Centerforce drills holes in the outside perimeter to remove weight to balance them. They are supposed to be neutral balanced. Mine feels like it is not properly balanced. I said in my first e-mail that the vibrations come on about 3500 RPMs. Actually it's more like 2200 RPMs.