If we were all designing the Model A from scratch as a committee, the argument between using mechanical or hydraulic brakes would be a valid one. But since the car came from the factory 90 years ago with mechanical brakes and we are a site dedicated to preserving the Model A, it's a moot point. Of course, hydraulic brakes are superior to mechanical ones in modern cars. After all, how many new car manufacturers still use mechanical brakes? But for our light-weight antique cars, properly rebuilt mechanical brakes are more than adequate, if not desirable. Simply slapping in newly relined brake shoes and relying upon original 90 year-old steel brake drums that have seen more than their share of truing and then expecting the braking system to function as designed is hardly fair to the car or the mechanical brakes as a class. A Model A with brakes rebuilt to factory spec's will send you towards the windshield in a panic stop. What more can you want?
I am prejudiced against hydraulic brakes in Model A's because in my 50+ years of messing around with these cars, I have seen unbelievably poor and stupid hydraulic brake conversions that some low grade moron cobbled together, making the car a rolling death trap. If you have been in this hobby long enough, you've seen that, too. On the other hand, well-designed systems - such as what Dennis Cling offers - that are properly installed and maintained should be as reliable as modern car braking systems. Although I am not a purist in the classic sense because I like a little extra umph in my engines, I do draw the line at making modifications that are visible and above all, irreversible. Once a Model A has been converted to hydraulic brakes, it is an expensive and frustrating experience going back to the original mechanical braking system. Of the many Model A's I have bought over the years, some had hydraulic brakes and each one of them either failed me at the wrong time (is there ever a "right time"?) or were unreliable and poor stoppers because of the lousy installation job. The only time a mechanical brake system failed me was my own fault because of a forgotten cotter pin.
This will always be a sore subject among our group. Those who have hydraulic systems in their cars and trust them are not likely to be changing their opinion. And those who restore the mechanical brakes and rely upon them will defend their use, especially since that is the original equipment. So, the two opposing camps will not convince the other to change their opinions. Where the problem arises is with the new guys coming on-board seeking advice whether they should convert their cars to hydraulics because a previous owner did not rebuild the mechanical brakes properly. The predictable pro and con arguments invariably flare up by the same folks. I, for one, would like to see the newbie at least TRY to restore his original brakes before converting to hydraulics. Quite frankly, if the guy isn't mechanically up to rebuilding the mechanical brake system in a Model A, I fear for his ability to make the tricky conversion to hydraulics! Would YOU trust a car thus converted by a newbie incapable of fixing his mechanical brakes?
I think we have to chalk this topic up as one that will never be resolved to everyone's satisfaction and agree among ourselves to disagree.
Marshall