Nate S
Well-Known Member
The governor is key to adjusting shift points at WOT but details of how it works are pretty poor from what I've seen. I thought I would try to understand it better so I disassembled a spare one, weighed the pieces, measured the spring and modeled the physics around how it functions. I then used that info (4700rpm unit) to predict what would need to be done for 5600 rpm and that matched a known 5600 rpm design pretty closely.
Below is a graph of gram force generated by the governor for 3 designs with known shift points. Note that changes other than the governor that change shift points will push these around. the governors will continue to be proportional to each other though. Pushing the 4700 rpm unit up 100rpm would also push the 5600 rpm unit up about the same amount.
The differences between the three are only in the mass of the inner and outer weights. The spring remains the same. Changing the spring can have odd results, changing only one weight can have odd results. If you aren't careful you'll move one shift point more than another. In fact without it modeled out it's almost guaranteed.
The lower part of the curve is a combination of inner weight, outer weight and spring weight. The upper part of the curve is primarily inner weight and less so, the spring rate. As you can see, changes to only the inner weight or spring will affect WOT shifts but have little effect on the part throttle shifts. Changes to the outer weight will affect part throttle shifts and won't do anything to WOT shifts.
I'm out of time right now. I'll add further detail in a follow up.
Below is a graph of gram force generated by the governor for 3 designs with known shift points. Note that changes other than the governor that change shift points will push these around. the governors will continue to be proportional to each other though. Pushing the 4700 rpm unit up 100rpm would also push the 5600 rpm unit up about the same amount.
The differences between the three are only in the mass of the inner and outer weights. The spring remains the same. Changing the spring can have odd results, changing only one weight can have odd results. If you aren't careful you'll move one shift point more than another. In fact without it modeled out it's almost guaranteed.
The lower part of the curve is a combination of inner weight, outer weight and spring weight. The upper part of the curve is primarily inner weight and less so, the spring rate. As you can see, changes to only the inner weight or spring will affect WOT shifts but have little effect on the part throttle shifts. Changes to the outer weight will affect part throttle shifts and won't do anything to WOT shifts.
I'm out of time right now. I'll add further detail in a follow up.