Brake Hoses, Lines/piping, And Fittings problems of the 1998 Toyota 4Runner

I am an owner of a Toyota 4 runner (1998), and certainly a safety issue exists with this vehicle. If depressed the brake pedal in an emergency (harder than normal operations), the rear seal (passenger side) will break, leaving only three (3) wheels brakes to stop the vehicle. Had to replace both rear seals at 68k miles. Again at 105kmiles the same issue. I strongly believed that the Toyota rear seal is not within specification of the pressure delivered to the brake lines. Please look into this matter, since a safety issue exists. Thanks.