Brake failure is also caused by brake drum thermal expansion in which brake shoe clearance becomes excessive from wear. This was largely remedied in the 1950s by self-adjusting brakes. Maladjustment with wear is still a factor in trucks with drum air brakes. A Canadian survey of randomly stopped heavy trucks found over 10% of trucks using self-adjusting brakes had at least one brake out of adjustment, due either to failure of the self-adjust mechanism or wear beyond the capacity of the self adjuster. Newer brake pistons ("cans") extend stroke from about 65 mm to about 75 mm; since about 30 mm of stroke is used just putting the pads in contact with the drum, the added 10 mm of stroke is over 25% increase in useful stroke. Longer stroke reduces especially wear-related fade, but drum brakes are still fundamentally prone to fade when hot.