Quote:
Originally Posted by nkaminar
Brent, the spring force is small compared to the pressure to force the shoes against the drums. The real reason that less pedal pressure is needed is because the friction is helping to force the shoes against the drums. You will have to do a free body diagram of the shoes with all the forces involved to understand how this works. One way to demonstrate this to yourself if to take a pencil and push it against a table with the eraser facing forward. As your increase the angle the force required to move the pencil increases with very little downward effort required on your part. At some angle you will not be able to move the pencil forward. That would be too much self actuating.
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There is one little issue that you are overlooking. On the floater area where the wedge pushes downward against the rollers, there is room for the floater to move laterally ....to a certain extent however the Wedge Stud still creates a positive stop (for the Wedge) where the shoes cannot rotate any further. When that happens, the wedge pushing downward no longer has any rotational advantage to provide what some are calling "self-energizing", so any mechanical/frictional advantage ceases.
Just a FWIW, my dad and several others tried something where they used an original Adjusting Wedge and used a hacksaw to cut and remove the wedge area. They just put that loose wedge inside the housing and re-installed the cap. The adjuster shaft was used to set the shoe clearance. This was done back in the 1970s, way before the FH Ted set-up. Instead of the Wedge against rollers, there was a triangle set-up that worked well however the downside is these triangle pivots would go over-center and lock the shoes against the drum if the shoes were not in proper adjustment.
The bottom line in this entire reoccurring debate is what are we/you/me trying to accomplish? Ford designed this car to appeal to Lady drivers. Many of these ladies were petite and lady-like (-not tough construction worker types) so the effort required to operate these vehicles had to be well within their capabilities. These cars were also designed to be driven 60 mph, so the original braking system had to be designed to accommodate a feminine driver's braking capability while also safely stopping from higher speeds. So have we become such 'wimps' now that we don't have the muscles in our right leg to depress the pedal on a stock braking system?
Sure, I am all about upgrades or improvements such as bonded linings or cast drums, but so often we get into the mindset that the original systems (generators, 6v electrical, updraft carbs, steering gearboxes, etc.) MUST all be upgraded if we want reliability and serviceability. From my experience around these cars, many of these things are just not needed to have properly functioning Model-As that will safely and reliably start, stop, and steer, -however it is indeed your car and your money, so make it whatever you want it to be.