29-10-2020, 06:02 PM
Hi Peter
It occurs to me that the Semi-Girling arrangement uses cylindrical plungers between the cam and each shoe tip. These are steel running in an alloy casting with just enough clearance to give a sliding fit. The dissimilar metals are a recipe for corrosion, so I suggest you try removing the drums and actuate the levers by hand to make sure everything is running free.
The only other thing I can think of which is humidity related is that the brake drum swept surface can get a thin film of corrosion (rust) which will considerably increase the coefficient of friction. Other posters have mentioned this. However, the effect is normally noticed after the car has been unused for a period. A couple of brake applications usually kills off the "sharpness". Maybe your drums have a different surface condition, not necessarily visible to the naked eye ?
It occurs to me that the Semi-Girling arrangement uses cylindrical plungers between the cam and each shoe tip. These are steel running in an alloy casting with just enough clearance to give a sliding fit. The dissimilar metals are a recipe for corrosion, so I suggest you try removing the drums and actuate the levers by hand to make sure everything is running free.
The only other thing I can think of which is humidity related is that the brake drum swept surface can get a thin film of corrosion (rust) which will considerably increase the coefficient of friction. Other posters have mentioned this. However, the effect is normally noticed after the car has been unused for a period. A couple of brake applications usually kills off the "sharpness". Maybe your drums have a different surface condition, not necessarily visible to the naked eye ?