That is my thinking exactly.
But it was bothering me that I did not understand exactly how it works. So I went out and played with it a bit. This is what (I think) I figured out...
The governor works by balancing centrifugal force against hydraulic pressure.
RPMs are controlled by output shaft.
The shaft has two primary pieces, the shaft body (also a bearing surface) and the stem inside.
The head is composed of a pair of assemblies, each consisting of an outer weight, a spring and an inner lever. The spring is oriented between the inner lever and outer weight such that the inner lever is pushed out by the weight swinging out. But the lever is "L" shaped and the leg hangs into the center over the stem so that the weight/lever combo swinging out pushes the stem down into shaft.
The stem inside is actually a simple multi-surface piston/valve combo. There are 3 slots in the shaft which allow fluid under pressure to enter and push the stem out into the head. As the stem moves out, the weight/lever assembly is pulled in. The slot opening also controls fluid access to drive parts of the throttle body.
When the head spins, the outer weights want to push out radially along the rotational axis. This force is countered by the stem trying to push out toward the head (due to hydraulic pressure) against the inner levers, thereby attempting to pull the rotating head in (against the centrifugal force). The only coupling between these inner levers and the outer weights is the spring which attempt to keep the inner lever moving along with the outer weight.
So, here are (as I see it) the relevant adjustment points.
1) Lighter weights would raise the shift points by allowing the stem to have sufficient strength to push out on the levers which, in turn, passes the force along the springs and pulls in the weights which lack the mass to overcome the hydraulic force on the stem. Once they do get sufficient RPMs to over come the stem and push it in, a shift occurs and fluid/pressure is rerouted to push it back out again (by pushing harder - more piston heads and more area under pressure) till it overcomes the weights and/or the springs again, resulting in another shift.
2) At first I couldn't figure out how heavy/light springs would affect things. Basically the only thing it can effect is the relationship between the lever and the weights. One possibility is that lighter springs will allow the inner lever to be pulled in more easily (by the stem pressing out) without having to bring the outer weights with it. It seems that this would allow the weights to swing out sooner than their mass vs. the hydraulic pressure would allow, effectively reducing the maximum strength of the weights against the stem. However, it seems that if this were the case, then it would get into a state where the weights were out, but the stem would not be pressed in by them, so there would be no shift and you effectively have a sort of stale-mate; unless other internal forces are at work that would break it…
Not sure yet exactly how that applies…
Maybe softer springs speed the stem's journey back out after a gear shift, thereby hastening the transition from one state to another (with respect to the valve function of the stem). In other words, there would be less lag time between shifts. What I am guessing is that heavier springs would (more-or-less) force the weights to come in, fighting centrifugal force and inertia, before the stem could move full circuit. And lighter springs would allow the stem to move quickly, and then the springs drag the weights along a moment later.
Or maybe the weights work for part of the equations, say at lower RPMs, and at higher rpms, the CF simply grows too high and the springs provide a somewhat steady rate to work against for the upper RPM work? There is also the possibility that the smaller levers themselves act as much lighter weights applying their centrifugal force in concert with the springs to help overcome the stem when the weights are already fully extended by compressing the springs. In this case, it would seem that the springs/levers control the higher gear shifts at speed, with the outer weights controlling things at lower rpms.
Does this make sense?
I'm hoping someone who knows tranys will clear this up for me. I suppose it would be useful to go through the hydraulics diagrams to see what gets/receives pressure via. the governor when, but it's getting late and I have to work tomorrow.
Bottom line is I've got 2 governors of unknown origins. Each appear to have the same weights, but they have different springs. My old one is much lighter and has 2 different rate springs in it. It is known to have been "built" but the exact spec is unknown. The one I was going to put (in until I found out the bell is cracked) is supposed to be stock (to the best of the seller's knowledge) but has a matched pair of considerably heavier purple springs.
