Coffee&Cars
Well-Known Member
Just my 2cent's worth. When a sprag fails it spins the first gear clutch. But it spins the that clutch drum at your engine rpm times the first gear ratio (2.45). So if you achieve lock up on your converter at launch at 5,000 rpm, and your sprag fails your clutch drum spins freely and zooms to 12,250 rpm and it explodes. This is caused buy spag failure and the weak sintered steel drum. We are dealing with stored kinetic energy here. To many rpm's and the drum just can't take it. Billit drums are not the total answer. They only raise the rpm failure point of the drum. Also a stronger drum when it does explode "at even higher rpm" it will increase the explosion making it even worse. The 904 has lighter parts so it takes more rpm to reach this stored energy limit. When you reach it's rpm limit it will explode too. There is no fool proof solution. It's all mechanical parts, they all have a limit as to what they will take. Besides the strongest parts you can buy, you need to have the best safety device you can put on your bomb. For more info on that PM me. I have built a new tranny blanket (yes, it is SFI certified) addressing the issues we have with the 727-B.
