ok, I know most of the details of the single mass conversion. I have a specific question. I already have an F-body flywheel. My question is: Are the f-body flywheels supposed to have weights pressed into the holes near the edge similarly to the dual mass corvette unit? My corvette wheel has shiney weights in various holes near the edge. However the camaro wheel does not. I need to know if it originally had those types of weights. It does however have a counter weight on one side and 180 degrees on the opposite side it has machining marks where it appears the factory removed material to aid in balancing. I need to know so I know if my camaro wheel is balanced correctly for its original application.
I plan on taking both wheels to the machine shop to have them deck the f-body wheel to match the dual mass one. As well as match balancing if its at all possible to do that with the dual mass.

 

Match balancing the two flywheels is what you need to do. I don't think it matters though how you get there though. Whether you drill holes to remove mass from the heavy side or add pellets to holes on the light side. If you were replacing your flywheel with another dual-mass, you would add weights to the same holes as your original. Since you are changing flywheels, it doesn't really matter if there are pellets in any particular hole as long as they match balance.

 

:lurk: I've been through this delima and never felt comfortable about the whole balance deal. I replaced my dual mass with a new one as mine had too much play between the masses. So, before the tear down I,too, asked the same type questions. So, I went out and got the weights for match balancing the wheels. When I took the flywheel off, I found it not to have any weights in the perimeter holes :eek: The previous owner said he had the clutch changed and didn't know anything about the flywheel. (he wasn't into cars that much). Now I'm wondering if my flywheel was an original or not; maybe the mechanic didn't know about matching the weights, etc, and no one to confirm a change or not. Here's my thinking: I figured the engine ran well in all RPM ranges and I figured it just didn't need any weights. Now I find out that GM balances the rotating mass with the clutch on! So, if I change a clutch, I'm supposed to rebalance the rotating mass, again?! Oh Great! Pull the engine to replace a clutch :cuss Now you se why I'm :lurk: ing? No one seems to have the answers on this, not even GM. Maybe dis time :skep:

I'll have the clutch change complete by next week. I'm hoping,no praying, for no vibrations. :blueangel:


[Modified by Strick, 12:58 PM 2/10/2004]

 

Strick,

I'd say leave the clutch out. Everybody you talk to will give you a different answer, but I was told a clutch assy is neutral. Some things to think about:
1) I'm not sure how easy it will be to chuck up a flywheel/clutch assy with the throwout bearing and everything in there.
2) It will be very hard to align the clutch in the right spot with out a crank and pilot bearing to guide the alignment tool. If the clutch is slightly off-center, it will cause an imbalance.
Now you could do all this if you had the crank out, but you don't. My advice would be to match what you have if it didn't vibrate.

 

The only clutch assemblies that are neutral balanced are those used on an internally balanced engine. Most of the C4 engines require a counterbalanced flywheel.

 

So are you saying that when you replace a stock C4 clutch, you have to have it match balanced to your old clutch? Can't the pressure plate bolt on in more than one way? Please explain more. I've never heard of this.

 

Are you saying that every time you have to replace a clutch you need to drop the motor and have it ballanced? Because the whole matched ballancing thing IMHO has some big problems. If you dammage the fly wheel in any way IE warp break ect... and normal material lost during use then you would be match ballancing to a flywheel that has changed since the original balancing.

 

Well Jeff, I'll let you know how it works out when I get it back together next week. This balance thing can get pretty deep if you let it.

 

When I switched to a camaro single mass FW on my 89 L98, I did not know about the weight issue. Well of course it shook like mad! So I took the stock DM and the neautral balance camaro FW to a balancing/machine shop. We came up with welding on mass:

I had no vibration after that.

 

Just curious, what kind of machine balanced it? And did your Dual Mass have any of the small weights in the holes on the perimeter of it?


[Modified by Strick, 5:35 PM 2/11/2004]

 

I have to go pick up a crankshaft at the shop in a while here and I will find out. I'll go look at the DM's small weights also.

 

Your dual mass didn't seem to have any in the holes that are visable. The small weights were to fine tune the balance between the flywheel and the motor, I THINK!

 

To go along with Pauls Pic, the results of neutral balancing my dual mass is below. You can see all the lightening holes around the cast weight. It is also milled down some. He also put several around the outside pointing toward center. Notice 4 holes that I circled are filled with rtv. Under the rtv are tackwelded 1/2" freeze plugs. You can dig up my post on this from a few weeks ago. Still haven't decided to use it yet.






[Modified by Jeff Hickman, 12:56 AM 2/12/2004]

 

He said 'clutch assemblies' so I assume he meant to include the flywheel in the encompasing statment. Either case the clutch disc and pressure plate are neutral balanced so you don't need to balance the PP w/ the flywheel.

Anyway, I took both flywheels in and told them what I wanted. They said 'no problem'. Place was recommended by different sources as 'best in town'. I requested to deck to match 'stacked' height or distance from crank to flywheel/PP surface. As well as match balances and chamfer PP to flywheel bolt holes to account for material removed from decking.
Should have it installed next weekend. I'm optimistic. It will probably cost a pretty penny though.


[Modified by y5e06, 4:06 PM 2/12/2004]