How to lighten a stock cast iron flywheel
#1
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How to lighten a stock cast iron flywheel
Start with your stock flywheel, In my case, 2.3L Turbo Ford
![](https://www.miataturbo.net/attachments/engine-performance-56/41031-how-lighten-stock-cast-iron-flywheel-dscf3813.jpg?dateline=1334940043)
Its weighs in at 20.5Lbs
Lets see how much weight can be cut off….
Next is to remove the clutch plate alignment pins….
![](https://www.miataturbo.net/attachments/engine-performance-56/41032-how-lighten-stock-cast-iron-flywheel-dscf3815.jpg?dateline=1334940043)
A slide hammer works well
![](https://www.miataturbo.net/attachments/engine-performance-56/41033-how-lighten-stock-cast-iron-flywheel-dscf3814.jpg?dateline=1334940043)
Mount the flywheel upside down, on the flywheel grinder
![](https://www.miataturbo.net/attachments/engine-performance-56/41034-how-lighten-stock-cast-iron-flywheel-dscf3817.jpg?dateline=1334940043)
Start buy cutting the excess cast iron down to the ring gear..
![](https://www.miataturbo.net/attachments/engine-performance-56/41035-how-lighten-stock-cast-iron-flywheel-dscf3818.jpg?dateline=1334940043)
Once that was flush, I weighed the flywheel again, that reduced the weight by .75 lbs (12 oz) now 19.75 lbs
Time to thin the fat from behind the ring gear…
![](https://www.miataturbo.net/attachments/engine-performance-56/41036-how-lighten-stock-cast-iron-flywheel-dscf3819.jpg?dateline=1334940043)
each pass, this machine cuts only .005-.008 off…
![](https://www.miataturbo.net/attachments/engine-performance-56/41035-how-lighten-stock-cast-iron-flywheel-dscf3818.jpg?dateline=1334940043)
the final weight is now 17.75 Lbs
I removed a total of 2.75lbs…. This should help the engine rev a bit faster, with out giving up too much torque..
Start with your stock flywheel, In my case, 2.3L Turbo Ford
![](https://www.miataturbo.net/attachments/engine-performance-56/41031-how-lighten-stock-cast-iron-flywheel-dscf3813.jpg?dateline=1334940043)
Its weighs in at 20.5Lbs
Lets see how much weight can be cut off….
Next is to remove the clutch plate alignment pins….
![](https://www.miataturbo.net/attachments/engine-performance-56/41032-how-lighten-stock-cast-iron-flywheel-dscf3815.jpg?dateline=1334940043)
A slide hammer works well
![](https://www.miataturbo.net/attachments/engine-performance-56/41033-how-lighten-stock-cast-iron-flywheel-dscf3814.jpg?dateline=1334940043)
Mount the flywheel upside down, on the flywheel grinder
![](https://www.miataturbo.net/attachments/engine-performance-56/41034-how-lighten-stock-cast-iron-flywheel-dscf3817.jpg?dateline=1334940043)
Start buy cutting the excess cast iron down to the ring gear..
![](https://www.miataturbo.net/attachments/engine-performance-56/41035-how-lighten-stock-cast-iron-flywheel-dscf3818.jpg?dateline=1334940043)
Once that was flush, I weighed the flywheel again, that reduced the weight by .75 lbs (12 oz) now 19.75 lbs
Time to thin the fat from behind the ring gear…
![](https://www.miataturbo.net/attachments/engine-performance-56/41036-how-lighten-stock-cast-iron-flywheel-dscf3819.jpg?dateline=1334940043)
each pass, this machine cuts only .005-.008 off…
![](https://www.miataturbo.net/attachments/engine-performance-56/41035-how-lighten-stock-cast-iron-flywheel-dscf3818.jpg?dateline=1334940043)
the final weight is now 17.75 Lbs
I removed a total of 2.75lbs…. This should help the engine rev a bit faster, with out giving up too much torque..
#2
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Also to get some more off. On the clutch side of the flywheel inwards towards the bolts you can see where the surface is ruffly 1/4 inch farther in than the clutch disc ride, slice that off. You can also bevel the outer lip of the flywheel.
I used to do this on a brake lathe for a few local round track guys.
I used to do this on a brake lathe for a few local round track guys.
#3
Cpt. Slow
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Boring. I had our russian lathe dude with 30+ years experience lop off the weight ring in the back. Took about 10 minutes total. I swear on our little 1.6 flywheels it's worth something like 4 lbs, but it's been a few years and that might be off by a bit.
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