Hey guys.. I have a question regarding the SPEC billet steel flywheel I have. I was told by the guy I bought it from that it is meant for internally balanced engines. However I noticed when I went to drop it off at the builder's shop that there is a weight installed on the back of it. I'm getting a new rotating assembly that needs to be balanced - will this flywheel work with it or are they going to tell me I need a different flywheel?

 

I asked the same question to the tech department at SPEC and this is the answer I got, literally:

The weight bolted on the back means it is extrenally balanced like the
factory flwyheel. When you remove the weight, it becomes zero (neutrally)
balanced.

I am having some vibration at 4500 RPM with a Stage II flywheel and pressure plate assy and trying to figure it out.

 

I have a Spec 3 clutch with aluminum flywheel. The weight was shipped loose (mounts to the rear - engine side). I had an internal balance engine assembly, so, I did not use it. The weight was intended for use of the stock assembly.

 

I also asked regarding mounting the pressure plate to the flywheel in a particular position and Dave replied the following:

Depends on whether the parts were ordered separately or together. If they
were balanced together by us, there will be a punch mark matching the two
pieces.

Hope this helps. I am going to check mine and make sure the punch marks are aligned.

 

Do you have any flywheel related vibration you can actually feel?

 

No vibration problems (7k revs) with an internal balance assembly (383ci Callies "Dragonslayer" crank/ 6" Eagle H beam rods/ -28cc JE blower series pistons). I also went with a neutral balance damper over the stock unit. The stock damper appeared to have an external balance weight. The SPEC series#3 6 puck clutch can chatter if slipped slow. I've replace the disc once. The SPEC unit does lock nicely. Also, went with a Denny HD aluminm shaft (high speed balanced). Alot of vibration with the stock driveshaft unit. B.

 

Well when I got my rotating assy back from the shop the weight was still in the flywheel. Does that mean they did it wrong?

 

It sounds like they did indeed balance the rotating assembly using the external weight. However, if you didn't tell them you wanted it balanced internally...then I don't think "they" did anything wrong. If you told them you wanted it balanced internally, IMO the machine shop should have noticed the counter weight on the flywheel...and asked.

Also, if you balance internally, many times the machine shop does not even use the flywheel...since it is intended to be neutral. There is a chance they never touched the flywheel and it is balanced internally. Most likely, there will be a "slug" of heavy metal in the crank if it is internally balanced. you should certainly ask the machine shop how it was balanced.