Are there any options to replace CC’s rear wheel speed sensor kit (De Dion)

[prisoner7]

I built a 2023 420 SV.

So, installing the sensor I could tell this was going to give me problems. Those are the thinest wires I’ve seen on a car.

After a driving about 75 miles my speedometer stopped working. And just as I feared, one of the wires broke at the connection point at the Econoseal.

FWIW - when mounting the sensor, I did not do the extra earth connection (Darren at build support said it was no longer necessary). I did add protective sheathing on the cable itself from the connection point on the anti roll bar bracket up to about 10 mm behind the econoseal connector. I have a series of mounting brackets with zip ties to run the cable up to the chassis side connection. Everything is pretty secure…but obviously not secure enough.

This is not a case of the sensor too far from the ring. The gap is about a ‘credit card width’ away. I did look at the “Speedometers” by Tony Whitley and the issue for me is the wire broke at the Econoseal…

Are there any options, or do I just to accept that this is a dumb design with such thin wires.

Thanks.

[Ainsley]

Is there play in the wires, are they bouncing about, are the wires too short putting some strain on the whole thing ?  There must be something causing them to break.

Have you a picture of the installation ?

I finished my build a few weeks ago, done 1400 miles and speedo still works.  I didn't see them as being too thin for the job.

[simon_h]

The wires aren’t too thin for the job as the current is minuscule but they might be a bit fragile for the environment. These sensors are normally used on stationary machines and aren’t designed for automotive use really as far as the wiring goes. All you can do is re terminate it and make sure there is plenty of strain relief so the wire isn’t hanging from the back of the terminal in the plug 

[John Vine]

I'd agree with the comments above re allowing plenty of slack in the sensor cable.  Can you post a pic of your set-up?  

From the earlier (text-rich) Assembly Guide:

 

From the new (pictorial) Assembly Guide:

 

This is how I set up the sensor cable during my build in 2008:

 

And it's still trouble-free after 55K miles!

JV

Edited July 28 by John Vine
speedo cable? Doh!

[prisoner7]

Based upon the above I'm guessing it is how I installed the cable. I'll be more careful with  the next one...thanks to all.

[ian.pursglove]

I must say that I had the same issue early on and the issue was that I followed the guide as to how to attach the [very thin] wire close to the sensor and the suspension travel just ended up pulling it clear and breaking the wire. a change of mounting position and no problems since.

[David Mirylees]

I saw a Caterham at Haynes today fitted with a round GPS speedo with trip etc. A quick google for 'GPS speedo with trip brought up a few options all around the £50 mark.
The one I saw had the GPS pickup positioned on the horizontal seat belt mounting rail. (it was about the size of a 50p coin.)