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Speedo sender unit.


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Can any member confirm that the Inductive sensor on the rear drive shaft is an NPN output. Manufactured by Schneider

XS108B3NAL2  Also the size of the pull up resistor would be helpful.

The new units from C/C appear to be 5.5 mm as opposed to the original unit which is  8. 0 mm thread.

Any information would assist.


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The sensor is NPN, strangely wired to the PNP connection on the speedo, meaning they have to install a 1K pull up resistor. 

The 5.5 mm sensor is way more stable than the old 8, cheaper and if purchased from CC they will include the adapter, so swapping over is simple.   I suspect they have deliberately made the adapter stupidly expensive for what it is to encourage purchasing on the complete kit.  

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Have just tried to fit one of the new sensors,had to remove the bracket to drill out a larger dia. Hole to take the adaptor.Also after fitting to the car realised I needed the later bracket to get the sensor closer to the toothed wheel,so am now waiting for that to arrive.

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Thank you Chris & Gulf 1

I was puzzled by the inputs to the head unit as it was as you state set up for a PNP.

Your Info re new 5.5 units assisted me in trying to understand the cost of an apparent threaded adaptor only as opposed to the complete kit. Do you happen to know the position approximately where the 1K pull up resistor is mounted?

Also a thank you to Gulf 1

Was the bracket you speak of on a Series 3 ?



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My early 360 kits bracket was fine (Oct 2015), strange.

The resistor is located near the speedo.  Caerbont publish wiring instructions on their website, but it’s on the assumption that Caterham doesn’t have anything special.  It also fits the wiring diagram, the caerbont instructions and the need for the resistor.

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New bracket arrived so tried to fit the new sensor but found the bracket would not allow me to fit the anti roll bar drop link.Spoke to Caterham who told me I had the wrong bracket.After arguing that  it was the one from their web site I was told that the bracket is listed under anti roll bar fittings NOT wheel sensor bracket, the logic of that was lost on me.However I have now got the "correct" bracket coming but I fear it may be the same as the one I originally started with.If it is I fear a bodge coming g on.

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The "correct" bracket has arrived but as I feared is the same as the original one on the car.However in the mean time I have fashioned a small bracket that bolts onto the original bracket and positions the sensor nearer to the toothed wheel and allows me to see the LED s for setting up and leaves enough thread on the sensor to  tighten both locknuts. 

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  • 2 weeks later...

Speedo works.

 The problem turned out to be the lack of a 1K Pull up resistor. (£0.14 Pence)

This is not to be confused with the ceramic resistor which is directly behind the tachometer.

The other points that are of note on this voyage of discovery are.

C/C new 5.5mm sensor is sent out with a nylon spacer if you are attempting to fit the unit to a CSR.

It will need drilling out if you wont to use it to bush the existing 8.0 mm hole. However the use of this adaptor masked the led indicator which helps in the setting up process.

So a new bracket was fabricated which allowed the sensor to be aligned to the center of the trigger wheel.

I have not been able to find the original 1K resistor and can only surmise that it was contained in the old ECU or its program.

The read out is rock steady and very accurate after calibrating it.

Thank you to all those who offered information over this problem.


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