I have one that's almost as big as my entire radiator on my car. Problem is, the car begins to overheat when sitting at an idle for several minutes, which my gut feeling says is because the fan isn't pulling enough air for the trans. cooler and radiator.. I put it in neutral and rev it to 2,000 RPM and the temp quickly drops back down when sitting in traffic and stuff (people next to me look over like "what the hell?" LOL). I believe that problem will be solved when I install an electric fan.
That modulator rod can cause even more problems than the downshift valve, especially for engines with big cams. It pushes against the throttle valve that modifies (raises and lowers) the main pressure. It is hydraulically connected to the line coast boost valve, downshift valve, throttle boost valve, cut back valve, the intermediate accumulator valve and the main pressure regulator valve and pressure boost valve. That throttle valve dumps pressure to the case at a specific vacuum level. When manifold vacuum drops it puts the main line pressureto the booster valves, and fills the 2nd speed accumulator so there is no hesitation when the servo is powered up to engage the intermediate band. If the rod is too long it restricts or stops the flow of oil to all these systems making the RPM high enough to overload the band, and clutches causing slippage when the later shift happens. Too short and it will cause early shifts that hurt performance. Pressure to the booster valves and triggering of the downshift valve need to be timed correctly to avoid either situation.
