Shift Cut Sensors

Angerole, Inc have supplied shift cut sensors to many top level teams and race car constructors. On this page we set out the different styles we make, how the system works, what you're going to see in your data system and offer some getting started advice. Please feel free to email us with any questions you may have.

We make two basic styles, knob and linkage. Both work just fine with all common engine management systems. Please click on either picture for a larger view.

Please click here for a PDF installation drawing of our knob style shift cut sensor

Although we make both types and stand by anything with our name on it, we prefer and recommend the knob style because:

• It produces a better signal
• It has better immunity to inertial and resonance effects
• The cockpit is a less harsh environment for the sensor than the engine bay
• The ECU is typically also in the cockpit so wiring is simplified

Our shift cut system comprises two basic components, the sensor and the amplifier. Whichever sensor style you choose, it comes with the amplifier and the mating Deutsch Autosport connectors.

Here is a view of our amplifier:

Inside this high quality, machined from solid case is a custom amplifier board. Importantly, our amplifiers feature user-adjustable gain and offset, making it easy to tune the shift initiation threshold and driver feel.

Shown below is an example of the output from one of our sensors:

Here, the red trace is the shift drum position and the blue is the output from our shift cut system. You're looking at a sequence of up and down shifts. The plot's Y-axis is in volts. In this particular case, the engine management is made by EFI Technology whose ECUs require a downward edge to initiate the shift event. Consequently, we set the amplifier's offset at about 3.5V so that there's plenty of room for the signal swing and tuned the amplifier gain to give about a 1.25V edge each way.

We would like to draw your attention to the excellent signal to noise ratio: the actual shift events show up as clean and well defined with a magnitude 20 times or more the background noise. This is a result of careful design and is the best guarantee of reliable function, meaning the absence of false shift events.

We would like to emphasise:

• Setting the gain and offset as described above is easily done by turning a potentiometer with a small screwdriver, taking just a few moments. You do not need to send the amplifier back to us. We supply instructions with each amplifier.
• Our shift cut systems are ambidextrous in that they can be installed to produce either a positive or negative swing on an upshift. As described above, EFI requires a downward swing, Motec and most others require an upward swing. It makes no difference to the sensor which will work just fine either way.

Our standard shift knob is designed to slip over and bolt to a 3/4" diameter tubular shift lever. The wire is arranged to run down the centre of the tube for tidiness and for protection. Most of the time, it is easy to incorporate this or our linkage sensor into an existing car. Sometimes it's not and for special circumstances we are pleased to offer custom solutions. The photo below shows a custom shifter we designed for Multimatic.

It is important to understand that we supply the shift cut sensor. Provided it supplies a usable signal to your engine management system our job is done. If you break your gearbox doing flat shifts because you set your cut strategy up badly, that's your problem and not ours. This said, we want your installation to be a success and offer below some pointers we have found over time to be significant. Feel free to use them at your own risk.

The data plot below shows a car accelerating through 4 gears leaving a corner with the shift cut operating. From bottom to top, the traces are throttle (note that the driver is nailed flat through 3 upshifts), gear position, speed and engine revs.

It happens this car was set up with equal cut dwells in each gear, meaning the engine cut time was the same regardless of the rev drop between gears. On the face of it, it looks like the match between cut dwell and rev drop is good for the 2nd to 3rd shift but the post shift rpm oscillation for the 3rd to 4th and 4th to 5th shifts suggest the engine was cut too long for the rev drop. That's what it looks like. Actually, we have found that right around the time the shift looks perfect on the data, the driver will start to complain the shifter is kicking his hand and the dog rings will start to wear quickly.

It seems to be desirable for the engine to still be off (and therefore still slowing) as the next gear is selected. Dwell does not seem to be critical provided there is enough. We recommend you start with plenty of dwell and shorten it as you gain experience. Often, we end up with about 100ms dwell when the rev drop is over 1000rpm (say 1st to 2nd) dropping to about 70ms when the drop is about 600rpm, as would be typical for a shift into top gear. We have never seen a bit of post-shift oscillation cause any problems.

We have also found it is productive to tune the amplifier gain and cut threshold value such that the driver has to pull quite hard to start the cut event. This both helps to prevent false cuts and tends to produce a faster shift because the linkage and drum indexing mechanism are preloaded before the engine cuts.