The time has come to replace the clutch again on my 94'. Last time I reused the DMF with a replacement kit from Carolina Clutch. This time around I think I would like to explore converting to a single mass flywheel. I am aware of the added noise and the need of a sprung hub disc, but I am curious about the match balancing. Carolina Clutch recommends match balancing the new billet steel single mass flywheel to the old OEM dual mass flywheel. I am in the Tampa, FL area and cannot for the life of me line up a competent machine shop to do this service. They all stare at me with a question mark on their forehead or crickets on the phone. I am curious as to how many of you have converted to a single mass flywheel and never had the new flywheel balanced?

Thanks,

Patrick

P.S. - I would prefer not to go with the RAM push style conversion, I would like to stick with the conventional/stock setup with the external slave cylinder.

 

Zero balanced flywheel and then add weight 23.4 oz/in (balance spec on the crank, for example, I added 5.2oz @ 4.50"... this was to the Fidanza Billet Aluminum Flywheel #198501, which needed a little bit of weight at the same location for zero balance.)

Fidanza and Spec both sell weight kits to add, and that's what I used, and trimmed slightly for the required specification. There's a location on the flywheel for the weight. Alternately, there are flywheels available with balance weights cast in (for OEM L98 and LT1/4 crank).

By the way, I've used a motorcycle wheel balancer on a different flywheel to zero balance (McLoud Billet Steel Gen 1 SBC, pressure plate bolted on) and needed to add a little bit of weight in the same area... and later it balanced perfect on the crank when double checking.

 

I appreciate the reply!

Bear with me as I am only 1 coffee deep this morning so far. The flywheel I am looking at is the heavy billet steel setup from carolina clutch. I believe it comes with the balance weight cast in. Are you saying I should be able to install it and go? This is on an otherwise bone stock LT1.

What I am having a hard time grasping is, why it would need any more balancing or fine tuning? A flex plate off an auto trans LT1 doesn't have these drilled holes around the perimeter and I don't think they are fine tuned like the DMF's were. Maybe the DMF's had those additional weights added to help with the characteristics of the separate moving halves of the flywheel and how each one (DMF) could be slightly different?

 

I believe what you'd maybe consider is buying the flywheel you'd like and assume it's got at/or near correct weight and then have it match balanced to an LT1 A4 flywheel. Here's a few year old thread where it was mentioned and I mentioned then that there was a local builder that had their own that they prefered using. Regardless of your purchase I believe you have it checked.

https://www.corvetteforum.com/forums...post1597635061

Mention what you're interested in buying by brand/part number to get thoughts!

***** I read Carolina Clutch notes and I believe if your car is apart now all you need to do is check the weight holes around the flywheel perimeter for weight pins. Are there any? How many?

 

I believe I have around 7 holes filled with weights.

 

It was that way when you removed it this time, the last time or you had that balancing done maybe with your last clutch job?

Another interesting read then maybe.

https://www.corvetteforum.com/forums...post1597626151

 

I feel like there is a lot of conflicting information in that thread but I do agree with the one poster that I feel all dual mass flywheels are balanced the same but some of them needed fine tuning due to the fact of the separate moving halves and that not all DMF's have the same spring tension, allowable movement, etc... which would indicate a need to balance them a little further. There is a strong possibility that their balance could also change with time as they wear and the inter springs/dampers wear? Do my thoughts make any sense?

I like the idea of match balancing it to an A4 flywheel, that to me, makes the most sense. Or at least checking it vs. one.

The guy I spoke with yesterday (John @ Muscle Machine) in Largo, FL felt he could not get an accurate reading on my DMF and it would be very tricky and could not guarantee and accurate match balance.

 

I never had any balancing done to my original DMF. It was the same way last time when I did the clutch job in 2012, and its the same way today.

 

My understanding is that all factory GM spec one piece rear main seal setups are balanced in the following way.

The front harmonic damper "neutral" balanced, which I believe means that assuming you are working with a factory GM spec one piece RMS style setup, all the front harmonic dampers are interchangeable in terms of keeping things rotating smoothly. The rear is "external" balanced which I believe is to say that no weight is necessarily added to the crankshaft but rather weight is added to the flywheel or flexplate to achieve balance. This I think is called neutral/internal front balance, external rear balance.

Because there is a "factory GM spec" for all of this, i believe that on a factory spec one piece RMS setup all flywheels and flexplates that of this correct balance spec are interchangeable...

This spec has some tolerance and error however, and so for high spinning motors I believe that it is advised to not simply rely on this factory GM spec and get the rotating assembly balanced outside the motor, (I am still confused why the pressure plate which adds a non trivial amount of weight isn't part of the rotating assembly as balanced by a shop, but perhaps it is because all the weight is uniformly distributed).

I believe for a lower RPM motor that isn't being beat on, you should be able to take your flywheel of choice and have it balanced the same as a factory GM one piece RMS setup flywheel or flexplate.

Correct me if I am wrong but on factory production cars, they don't balanced each rotating assembly individually... but rather rely on the consistency of manufacture and this GM one piece RMS balance spec for the flywheels and flexplates to achieve production tolerance rotating assembly balance?

 

Yes, I think you are 100% correct. All automatic flywheels should interchange without being match balanced to the previous flywheel as long as it has the appropriate factory rate counter balance weight on it. Same with the manual flywheels.

It is interesting that both Ram and Centerforce say their flywheels need no additional balancing or match balancing, they can be thrown on and go. Whereas carolina clutch recommends to have them balanced. Again, I think the additional balancing to a DMF is for the flywheel itself, not necessarily the engine it was on. Correct me if I am wrong.

 

The L98/LT1/LT4 flywheels are externally balanced and there is a GM spec for that amount of imbalance. Balance within the GM spec should be good enough. I swapped a '90 L98 dual mass onto my LT4 and it worked great.

Some of the aftermarket flywheels are balanced to the GM spec or they are neutral or zero balanced. Make sure you know which you are getting.

Some of the "balanced" flywheels are not done correctly. I had a SPEC steel flywheel that was "balanced" to the GM spec, but it caused a vibration at about 3000 rpm and higher. When I took it apart I found that the "balance" was way off (about 20 gr). So my recommendation is to have your choice at least checked.

Good luck.

 

Copy that, and thank you! So in theory, I should be able to take the new SMF and an Automatic flywheel/flex plate to a machine shop and have them atleast run it and make sure it matches the GM spec on the auto flywheel? At least that would make sense to me?