Flywheel Metallurgy	Part No.	Description of Wheel
Cast/Steel	11A2	CBN
Cast Iron	800000	Softer than 801116 (narrower back)
	801112	Italian OE spec's Best all round wheel
	801112A	Kinik similar to Italian 801112
	801116	Harder than 801112/FGW57
	801119	KG Ceramic grain, excellent for very hard material
	FGW 57	USA spec's similar to 801112
Cast Steel	FGW 54	Softer than 801112/FGW57
	800125S	Straught sided 5
Billet Steel	Bv259977	Flaired Cup White
	801119	KG Ceramic grain, excellent for very hard material
100mm cup wheel	BV203939	Recessed flywheels
100mm cup wheel	81814	Recessed flywheels Pink
150mm cup wheel	BV259977	Recessed flywheels

Match the stone to the materialMost flywheels are cast iron (soft) but there is an increasing number of cast steel; (medium) many trucks, bus’s and agricultural :billet steel (hard) many new European models including VW & late V8 GM vehicles.

How to test a flywheel for Hardness
For good results, softer flywheels need to be ground with harder stones. Harder flywheels need softer stones. To determine flywheel hardness; spark test a flywheel before grinding. Using whatever grinding wheel is on the machine, briefly touch it to the flywheel and watch the sparks fly.

Cast Iron:
(soft) flywheels make a deep red-orange spark that travels only a short distance before burning out.

Cast Steel:
(medium) flywheels make a light orange to golden spark that travel further than cast.

Billet Steel:
(very hard) flywheels make a bright yellow-white spark that travels a long distance.

Coolant:
It is absolutely critical that a good quality coolant is used, SAE 187 is an excellent product but should not be used in a greater percentage mixture than 3%.