[drolston]

The physics involved supports the observation that you can not tell the difference in braking between having the linings in the right way or reversed. The drag force of the shoe is the coefficient of friction times the wheel cylinder force applied, regardless of the area over which that force is spread.

The rear shoe gets the bigger force because of the larger wheel cylinder diameter in that direction. Maybe they used a bigger lining so that the pressure (force/area) would be more equal between front and rear shoe. That would tend to equalize the rate of wear of the linings.