Roller sprag failure PowerGlide. This was the result of a street burnt out. Continued driving grinds the components up like a concrete mixer in a short time. If you suspect a problem, noise, loss off power etc. IMMEDIATELY stop the engine and have your vehicle taken to a transmission expert for diagnosis. The ground up parts in this example have contaminated the whole transmission and cooler. This supercharged GM should have had a billet back, furnace brazed, anti-balloon plate, steel turbine hub, Mechanical Diode one way clutch, needle thrust bearing equipped, race converter fitted as was advised but declined by owner.


The GM PowerGlide transmission is a tried and true tough unit & does not “just break driving normally from lights”. But it does have limitations. It won’t accept being shifted from a forward gear to reverse or to neutral and back to a low gear under full throttle. Older cars have shifters that may not protect against shift errors. Always invest in a quality race type shifter, to prevent damage from shift errors. Torque converters also need special attention if they are to be used in high power applications. Many are made from units designed originally for power and torque ratings of 50’s & 60’s engines.  A cheap option will cost a lot if it fails. Take advice on recommendations for your application.

Treated with respect this transmission will give years of reliable, trouble free & fun operation.