JUN is OK...... They do not warp, But the friction area of the flywheel is extremely thin. They tend to burn up clutches faster because they run hotter and the co-efficient of friction goes away on the clutch disc material as it heats up. They always are very blue with insane hot spots when you pull them out all the way through to the back side. Also They are throw away when they get cooked. JUN says not to resurface them. With insert flywheels you can replace the insert. The aluminum flywheels carry the heat away better. The hard Chromemoly surface of the JUN slips sooner on a clutch dyno with the same pressure plate clamp load and the same clutch material. We have several drag racers out here dumping the clutch at 6000 and 7000 rpm with the RPS flywheel and Max 6 puck and they are holding up very well. WXY just did a 1.55 60 ft with slicks and his RPS Flywheel with RPS MAX 6 Puck clutch this last week end.
