Steel flywheel

[europa88]

After my gear reduction starter stuck on the ring gear and destroyed its self along with the ring gear, I am removing the engine and transmission to replace the gear and tidy up the front cover area, which has some oil leaks. As the water transfer pipes are 50 years old now, I may invest in some stainless steel replacements too. Just toying with the idea of a lighter flywheel in steel whilst I'm doing this and I'm not sure of the advantages over the original cast iron one. Mainly because the cast iron one has been balanced as a complete assembly with the crank, rods and pistons. The new flywheel is a Burtons steel flywheel with ring gear already on and should be lighter. I'm led to believe that a lighter flywheel helps acceleration at the expense of a less smooth idle.

[Clifton]

Transmissions rattle more with light flywheels. Acceleration will be better but taking off from stops is more of a challenge, shifting is a little less smooth.  If weight and acceleration are your main priority you will be happy with the expense of street ability.  If you ring it out and power is never enough and like it to rev quick, you'll be happy. If you rarely beat on it and drive casual, maybe not so happy. As far as balance. A flywheel should be balanced separately. I've used two lightweight ones. Both were factory balanced.

[Pfreen]

I have the Fidanza aluminum flywheel on my tcs.  I can confirm the tranny rattle at low rpm below 800 rpm unloaded.  My car has ac and it did negatively affect the idle with the ac on.  My idle is set at 1000 rpm.

I really never noticed any difference in the clutch at startup or shifting.

I really wouldn't say the performance difference was noticeable.  It does rev more quickly in neutral.

I attached the photos of the weights of the stock and aluminum flywheel.  Btw, the Fidanza clutch surface is bolted on steel.

[dakazman]

  Quick question? I assuming their are three separate pieces then . If so are the pieces sold separately so they can be changed out? That alone would save you time/money in the long run.
Dakazman

[jbcollier]

On a street car, a lightened flywheel will mostly affect idle, clutch engagement, and revving the engine in neutral.  The first two negatively.

Yes, reducing rotating mass that needs to be accelerated helps to increase the rate of acceleration BUT the mass that needs to be accelerated also includes transmission internals, diff, half shafts, axles, drums/discs and wheel assemblies.  The greater the diameter, and further out on the diameter that mass is located, the greater the effect.  Obviously where you can spend money to the most effect is tires and rims.

I have run lightened flywheels on my hopped up bikes/scooters.  There the flywheel is a much more significant percentage of the total mass to be accelerated.  Yup, they are more responsive.  But responsive both ways.  In other words they also respond quicker to negative inputs like hills and winds.  And, yes, they are ridiculously easy to stall.

I do not feel a lightened flywheel is worthwhile on a street car.  Spend the money elsewhere.

YMMV

[Pfreen]

Dave,
The steel friction surface can be changed out.

[dakazman]

  Thanks, Pfreen,
    I wish you could also change out the ring gear, that would be the best of all worlds. \
       my machinist wouldn't even cut down the original flywheel until I showed him the specs.
Dakazman

[Pfreen]

I think you can.  Check the Fidanza website.

[europa88]

Transmissions rattle more with light flywheels. Acceleration will be better but taking off from stops is more of a challenge, shifting is a little less smooth.  If weight and acceleration are your main priority you will be happy with the expense of street ability.  If you ring it out and power is never enough and like it to rev quick, you'll be happy. If you rarely beat on it and drive casual, maybe not so happy. As far as balance. A flywheel should be balanced separately. I've used two lightweight ones. Both were factory balanced.

I do track it occasionally and like to rev the car on the street where able (not so much) so I don't know. The steel flywheel is 6.5KG's and isn't ultra-light. I don't know how heavy the cast iron flywheel is until i get it out. I intend to build a steel short block either now or some time in the future, so I might as well do this now I guess. Thanks for the input 

[europa88]

On a street car, a lightened flywheel will mostly affect idle, clutch engagement, and revving the engine in neutral.  The first two negatively.

Yes, reducing rotating mass that needs to be accelerated helps to increase the rate of acceleration BUT the mass that needs to be accelerated also includes transmission internals, diff, half shafts, axles, drums/discs and wheel assemblies.  The greater the diameter, and further out on the diameter that mass is located, the greater the effect.  Obviously where you can spend money to the most effect is tires and rims.

I have run lightened flywheels on my hopped up bikes/scooters.  There the flywheel is a much more significant percentage of the total mass to be accelerated.  Yup, they are more responsive.  But responsive both ways.  In other words they also respond quicker to negative inputs like hills and winds.  And, yes, they are ridiculously easy to stall.

I do not feel a lightened flywheel is worthwhile on a street car.  Spend the money elsewhere.

YMMV

Sounds like good advice JB. I may do it though, just because hopefully I'm gonna be building a higher revving motor with a steel bottom end sometime soon. Just sounding out the wealth of knowledge on the forum...It never disappoints 

[Pfreen]

Transmissions rattle more with light flywheels. Acceleration will be better but taking off from stops is more of a challenge, shifting is a little less smooth.  If weight and acceleration are your main priority you will be happy with the expense of street ability.  If you ring it out and power is never enough and like it to rev quick, you'll be happy. If you rarely beat on it and drive casual, maybe not so happy. As far as balance. A flywheel should be balanced separately. I've used two lightweight ones. Both were factory balanced.

I do track it occasionally and like to rev the car on the street where able (not so much) so I don't know. The steel flywheel is 6.5KG's and isn't ultra-light. I don't know how heavy the cast iron flywheel is until i get it out. I intend to build a steel short block either now or some time in the future, so I might as well do this now I guess. Thanks for the input 

I showed a photo of the weighed stock cast tc flywheel.  It is 15 pounds or 6.8 kg.

[europa88]

Transmissions rattle more with light flywheels. Acceleration will be better but taking off from stops is more of a challenge, shifting is a little less smooth.  If weight and acceleration are your main priority you will be happy with the expense of street ability.  If you ring it out and power is never enough and like it to rev quick, you'll be happy. If you rarely beat on it and drive casual, maybe not so happy. As far as balance. A flywheel should be balanced separately. I've used two lightweight ones. Both were factory balanced.

I do track it occasionally and like to rev the car on the street where able (not so much) so I don't know. The steel flywheel is 6.5KG's and isn't ultra-light. I don't know how heavy the cast iron flywheel is until i get it out. I intend to build a steel short block either now or some time in the future, so I might as well do this now I guess. Thanks for the input 

I showed a photo of the weighed stock cast tc flywheel.  It is 15 pounds or 6.8 kg.

Sorry should have looked closer