If you remember the block and light signals on the platforms then do remember the SP telling them that their vehicles were too light for reliable detection as they ran into a similar issue with the Budd cars on the Sunset, and that to improve detection it was suggested that Bart add wheel scrapers to the A cars to ensure a shunt.

I can still remember the squeal of the wheel scrapers when riding those cars until they got detection straighten out.

Also I have to say that the ride on Bart is smoother after the wheel profile change, and it is reasonably quiet on the ballasted section of the right of way, could the noise be due to the inherent stiffness of the raised and subway construction, that does not allow the rail to flex in the same manner as convention ballast and ties?