I finally heard back from a company - perhaps a major player - concerning controls for a sequential transaxle for a GT40, or other vehicle.
First, for those not up to speed, here's an overview. Sequential transmissions/transaxles are typically available with a torque converter (Auto trans, no clutch pedal), or with clutch pedal. Sequential transmissions are typically used for high horse-powered off-road vehicles, and for track racecars. The off-road sequential users typically shift with the common shifter supplied by the trans company or a third party vendor, and typically do not employ supplemental electronic or mechanical shifting equipment.
The true high-speed race vehicles typically do employ supplemental electronic and mechanical shifting equipment capable of making gearshifts in milliseconds and at wide-open throttle (WOT). For the brainiacs only: 1 second (s) = 1,000 milliseconds (103 ms) und 0.001 second (s) = 1 millisecond (ms). 1 millisecond (ms) = 1000 microseconds (µs) und 1 second (s) = 1,000,000 microseconds (106 µs) 1 microsecond (µs) = 0.000001 second (10-6 s) = 0.001 millisecond (10-3 ms).
Mechanical and electronic assisted shifts can be made somewhere between 45ms and 245ms depending on the system installed. Some vendors claim you can down shift through 5 gears in less than a second – though I can’t think of a time when that might be necessary.
The supplemental shifting equipment consists of two major categories:
The first category includes electronic sensors and processors. Their purpose is to vary the engine RPMs to the proper speed at the proper time preceding a shift, to reduce wear on the gears. For up shifting, the controls typically either cut the EFI fuel supply, and/or, cut the spark to the engine. Such action results in a drop of engine RPM to more closely match what that RPM should be when an up-shift is made. To make that crystal clear: if one starts out in first from a still vehicle, and winds out to redline @ 6800, then the RPM should be dropped to 4000 when the shift to 2<sup>nd</sup> gear is made. These numbers will vary depending on gear ratios and redline maximum. For downshifting, the controls attempt to raise the RPM to more closely match what the optimum RPM should be when a downshift is made.
The other purpose these electronic modules can serve is to signal the second category of mechanical shifting equipment to make the shift, thus eliminating the need for the driver to do anything more than actuate a shift by: pressing a button, moving a sick shifter very slightly, lifting up or pressing down on a steering wheel paddle shifting mechanisms, or a lever connected to the steering column.
The second category of shifting equipment includes mechanical devices that makes the up or down shift when a signal is received from the electronic equipment to do so. The mechanical shifting equipment can consist of the use of: pneumatic actuators (Compressed air), electric solenoid actuators, and hydraulic actuators. Each product manufacturer usually only employs one of those three choices, and simultaneously touts their choice as the best, while enumerating the cons of the other types. This is but one major reason for the mass confusion that would-be-buyers, especially those not involved with NASCAR, would be subjected to when contemplating a sequential for their GT40 or other performance type vehicle.
Below is a copy of one text exchange between a vendor and me. The vendor’s name was redacted.
Thanks (deleted). For your email. NOTE, (deleted) is the Operation’s Manager for Roush Engines, and not for FAST. But, (deleted) will know which FAST ECU they will employ. I will attempt to send you a photo, and maybe the size of the very traditional GT40 steering wheel, so we can decide what look we desire for the shifting method.
I do have additional questions.
1. Apparently, the circumstances of sequential transmissions are rather an enigma, to me anyway. The transmission makers say that if you tip your tow on the gas pedal to remove the torque, then you can shift up or down without a problem or any other controls. Granted, for racecars, where the driver would rather run at wide-open throttle during shifting, an electronic control would be the answer. Others, including you, have non closed-loop systems for a fraction of the cost. So, I continue to ponder the circumstances, since this car will not be raced.
The vendor replied:
Well, the obvious benefits of paddleshift is the ability to keep both hands on the wheel and safely change gears anywhere including mid corner ! On a street vehicle it brings a whole level of safety to not torque pitching the car with so much power and having an incident on street.
The Easyshift is very good for upshifts, but the problem with downshifts is that you need some method to physically open the throttle. With the paddleshift, we already have the air supply to drive the pneumatic blipper, but that's not an option with the easyshift. The downshift function of the easyshift was mainly added for those who want to experiment with their own hardware (solenoids, blipping devices, Drive by wire setups).
There's also another problem with downshifts, and that's the timing of the blip. With the paddleshift system, we fire the blip ahead of the shift to try to get the engine to respond at the correct time.
2. My engine will have a FAST ECU, and it will be programmed to limit the RPMs of the engine - will cut fuel and spark - if engine is over revved, so missing a shift should not be a problem even if we have no transmission controller. Is this correct?
The vendor replied:
It will only be limiting RPMS on driving the engine up the rpm.. when you downshift and drop the car into gear our system will not allow a downshift if the engine under drive circumstances would indeed go past and exceed a safe engine rpm value in our system. Your fast ecu cannot safeguard this scenario.
3. I am also interested in the circumstance when the driver is in the car, the engine is running, the car is in neutral, and the driver reaches over and accidentally hits the shifter, and the car engages into 1st gear. Is this true, or is there some safety aspect that you must do to eliminate the car from entering neutral by accident?
The vendor replied:
There most definitely is a safety mechanism built in. Let’s say you had buttons on the steering wheel for shifting as well as your stock shifter with micro switches in place. If you were in neutral you could hit any and all of the buttons / lever and no shift would occur until you push a button (usually put on the dash) and pull the lever for an up shift or the up shift on the steering wheel.. this is the safety mechanism for not accidentally going into gear when in neutral.
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