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Author Topic: Flywheel weight before and after lightening & other questions  (Read 340 times)

Offline Rainman56

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Flywheel weight before and after lightening & other questions
« on: October 27, 2019, 09:17:02 am »
Just curious how much weight is removed when lightening the stock flywheels on the 500 &250's..........I've run both on a 500 and really didn't notice any if much difference...Just curious if anyone has actually weighed a stock vs "lightened"...

Also is there a max amount that can safely be machined off or do builders that machine them vary in how much weight they remove?

I need to get another stocker lightened,who do other members get to machine theirs???
Can,t fix stupid.:)

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Offline MotorGeek - Jerry Hall

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There is not much to be gained when lightening a stock flywheel. 

It is not how much weight is removed, but where the material is removed.  A few ounces could be removed on the vertical edge of the shell and hub or a few ounces on the outside of the shell.  Material removed on the outside of the shell will give a greater reduction in the moment of inertia than removing material from the vertical edge of the shell and hub.

I have machined a lot if flywheels but I do not recommend it.   There is not really a safe amount to remove.  How much can be removed depends upon the highest RPM the engine may ever attain.  The porting and pipe determines the RPM where the engine will spend most of its time but we cannot predict how high the engine is going to rev with a missed shift.  We cannot predict what RPM the engine may experience when mistakenly is down shifted rather that up shifted to the next gear. 

I have seen the outer shell of flywheels explode on machined flywheels but never on a stock flywheel.  The question was.......was the flywheel machined too thin or would a stock flywheel have exploded if the engine experienced the about the same RPM?

Offline Rainman56

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Thanks Jerry...The one I had lightened actually broke the center hub from the outer flywheel...Had a stock one lying around and simply threw that one on...Like I said I really didn't notice any difference.
Can,t fix stupid.:)

Offline Rainman56

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Thanks Jerry...The one I had lightened actually broke the center hub from the outer flywheel.Didn't hurt anything just quit running abruptly lol..Had a stock one lying around and simply threw that one on...Like I said I really didn't notice any difference.
Can,t fix stupid.:)

Offline Q2W

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Thanks Jerry...The one I had lightened actually broke the center hub from the outer flywheel...Had a stock one lying around and simply threw that one on...Like I said I really didn't notice any difference.

That's actually a common problem for these flywheels once you start adding power.  Every engine i've seen modded that didnt have the flywheel's hub weld nuked shorty after.

I know of the a few small hub lighten flywheels that were welded that havent had any problems. I believe the lighten large hub flywheels still weigh more than stock small hub ones.  Grkguy posted a comparison on this site once.

Offline MotorGeek - Jerry Hall

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I do not think that you will ever notice the difference between the small and large hub flywheel when you ride (compare) the two.  The increase in mass of the large hub flywheel is too close to the axis of rotation to increase the moment of inertia appreciably. 

Offline Rainman56

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Thanks Jerry...The one I had lightened actually broke the center hub from the outer flywheel...Had a stock one lying around and simply threw that one on...Like I said I really didn't notice any difference.

That's actually a common problem for these flywheels once you start adding power.  Every engine i've seen modded that didnt have the flywheel's hub weld nuked shorty after.

I know of the a few small hub lighten flywheels that were welded that havent had any problems. I believe the lighten large hub flywheels still weigh more than stock small hub ones.  Grkguy posted a comparison on this site once.

Mine was a small hub flywheel that had been welded and lightened and the center hub broke from the rest of the flywheel.I've seen one other somewhere on here that did the same.
Can,t fix stupid.:)

Offline GrkGuy

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The small one weighs less than the big one.
life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sidays totally worn out shouting "HOLY SH*T...WHAT A RIDE!"

 

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