For every Powerglide racer out there, at least one broken Powerglide story can be told. Of course, these things will happen when you yank the front wheels off the line with a tranny designed about 40 years ago, whose sole purpose in life was to let Ma and Pa and Grandma and the kids cruise along smoothly for 100,000 miles in trouble-free comfort.

Obviously, breaking a Powerglide built with stock components is not especially hard to do. It's also very predictable as to which of the stock components will fail. John Winters has studied the 'glide and figured out the likely order in which the parts in a Powerglide will fail. It is this pattern of carnage that led him to design and develop replacement parts for the stock units.

The first component to fail when a stock Powerglide hits the track is usually the high-gear clutch-drum hub (right). J.W. manufactures both billet-steel and -aluminum versions that are longer than stock to accommodate the greater number of clutch discs used in racing, while improving fluid flow.

Winters provided DRO with the results of his four decades of observations and experience on this issue. The first component to fail, usually at power levels of 300-350 horsepower, is the clutch hub in the high gear clutch drum. If a transbrake is installed, or the fluid volume or pressure is raised to make a Powerglide suitable for racing, Winters has found that the stock hub will usually fail in a very short time.

Next in the failure list would be the input shaft. A stock shaft usually gives up the ghost when it is asked to handle 500 horsepower and the torque that goes along with that number. The output shaft will be the next piece to fail when the power goes up substantially from there, to be followed by the planetary gears. And just when you have all this stuff beefed up and think that everything is fine, the case itself can fail when the power goes up even more.

About the last thing to break with very high horsepower loads is the planetary gearset. J.W. now builds all-aftermarket planetaries with either aluminum or steel carriers, with standard or "shorty" output-shaft lengths. Two versions of the gears are available: the 8620-steel models are guaranteed for up to 795 horsepower; above that power level, E9310 chromemoly is used.

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