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Crankshaft sprocket design

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Hi all,

I'm designing my own crankshaft timing sprocket with trigger pattern. I have seen different trigger patterns but due the space I'm limited. At the moment the engine is running with 12-1 but I was wondering if it would be any better using 24-1.

I want to send it to be produce by CNC. Any recommendations on Carbon steel grade?


Attached Files

If you can reasonably fit 24 I'd do 24.

24 is my go to when a disc has to be made as more teeth often isn't necessary, but when I've used 12 the resolution isn't ideal.

More teeth will give better resolution - might be a good idea to check what the ECU you intend to use supports, first?

My minimum preference would be a 36-2, or the optimal is a 60-2. If your ECU cannot support either of these options, then I would question the choice of ECU being used. Most modern reference patterns use a 60-2 and a variant of the Bosch 140 40 cam patterns. Some engine will also have a 36-2 but this doesn't appear to be as common now.

Thanks for all responses,

-The ECU is Link storm G4+

- I can try to see how much area is left on every teeth if I do 36 but it worries me if the smaller area can create any problems while the engine is at hi rpm.

Anyone knows what should be the minimum area or gap between teeth?


It all depends on the sensor - smaller diameter sensors can often sense smaller targets (teeth), I would make the standard gaps and teeth the same size. You would probably be ok with most crank sensors with a 3 - 4mm tooth size. Of course it best to test that, make a prototype and mount it to a drill motor.

The sensor that you are using should have a specification sheet available that provides information on the minimum and maximum tooth dimensions that can be used. Once you have this information you can then design the optimum trigger wheel to suit.

An example

Thanks for all the comments, I’m using the GS100502 sensor.

Following the specification sheet I will have to stay on 12-1. I have done 24-1 and 36-2 designs but the space between teeth is below 10 mm that is the optimal for this sensor. Doing 24-1 with just 2.5 mm tooth width has 7.5 mm between teeth so still not enough.

Does anyone have used this sensor with any smaller distance between teeth? I would like to know the feedback.

Attached Files

That sensor looks a lot like one of the sensors that MoTeC sells. MoTeC Flange Mounted Hall Effect Sensor

If that is the case, I have used these sensors with M1 ECU's on 60-2 trigger wheels and 48 tooth ABS tone rings for wheel speeds without issues. The tooth spacing on those systems are much smaller than the minimum recommendations in that document, more like those shown for the 36-2 trigger wheel.

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