Speedo

[JNC]

Last night when pushing the high end of the Speedo the needle was all over the place ! . I have a five speed box , Were the wheels turning to fast for the Speedo ? Does it have an electrical sensor ? . Any ideas 

[Garry7]

How the speedo works depends upon the age and configuration of the car.

How old is your car?

I have lots of experience (not all good) of the rear wheel driven electrical sensor version fitted to the newer cars - mines 2011.

[JNC]

My car is 2012

[ScottR400D]

When I first pushed my car to higher speeds, around 100mph, the speedo kept dropping out. I moved the transducer a little closer to the segmented disc and it's been fine since.

[Jonathan Kay]

Check that there's a wire coming from the sensor in the gearbox (rather than a wire from a wheel or a mechanical cable coming from the gearbox).

For the electronic drive from the gearbox:

1. Have a good look and play with the speedo sensor at the gearbox and the wiring.
2. There's a wiring fix and a Workshop Notice (available from JV). (But I thought that the symptoms were failure and fuse blowing rather than dropping out.)

For the electronic drive from near a wheel:

1. There's great advice from JV on getting the clearance right. Same point as ScottR400D's.

Jonathan

[JNC]

Thanks all ! , tonight I removed the sensor at the rear offside wheel cleaned the area and made sure all was ok , I checked the tightness of all the bolts refitted the sensor , found the only earth removed cleaned refitted and tested all seems ok now. I will fit the extra earth when Gary7 sends the CC PDF . 

[JNC]

Thanks Garry7 I have got the CC PDF of wire mods, It looks a very easy job to do. It's a bit worrying that if the sensor fails it blows a fuse and cuts out the engine  !!.  Thanks again chaps.     

[JNC]

Update !! . Fitted extra earth wire readjust sensor done the light test and road test started off ok then erratic again ! . Today went on a earth hunt following black wires to earthling points clean and retighten them , Found the main earth to the bell housing very loose I thought this is it the cause of the problem  NO IT ISN'T . Now what ? Please help. Is it time to buy a new sensor ?.

[John Vine]

Rather than buy one (they cost around £70, I believe), is there someone you can borrow one from, a least to run a test?

Another possibility is that the speedo itself is faulty.  When mine first started playing up, CC were able to lend me one -- it fixed the problem.

JV

[JNC]

John when I did the sensor light test by hand all seems to be ok plenty of flashing  if it's to close to the cog the Speedo does not work at all  so it suggests the sensor is working ? . So do you think it's the Speedo its self .

 

[John Vine]

When you say "plenty of flashing", did the LED light up for every tooth?  Clearly it needs to, but if it does, it suggests the sensor is working ok.

James Gibson (ex CC Aftersales Manager) offered to lend me a speedo after I'd reported endless problems with mine (needle dipping to zero whenever I applied the brakes or used the indicators, and stopping working completely after about 50 miles of high-ish speeds).  The new speedo worked perfectly, and CC seemed content to let me keep it FOC.  All this was some years ago, before I was aware of the official earth mod, so I don't know whether it was entirely the speedo's fault.  Late in 2014, I had some chassis repair work done at CC.  On the journey home, the speedo was waving about like a semaphore flag. I checked the air gap - 0.5mm.  Then I applied the WN572 earth mod and all was back to normal.  I can only assume that the chassis repair had affected the speedo circuitry and earthing in some way.

So, if you can persuade CC to lend you a speedo, at least you could eliminate one more variable.

JV

[JNC]

John what's the importance of cutting the earth wire and only using the new earth From the sensor ?

[John Vine]

The standard sensor earth is via a long loom wire. It was this wire that was believed to be picking up stray electrical interference, which confused the speedo.  Earthing the sensor directly to the chassis avoids this.

JV

[Silverback]

Same here today. Speedo has been rock steady reliable since birth (2014) but today's shakedown at Bedford saw the speedo become erratic above 100mph to then die completely only to live once again on the (admitedly) more sedately run home.

Perhaps it was the shock of the sunny weather!

[JNC]

I spoke to Tony at CC today, I am convinced it's down to the Speedo now but Tony thinks it's more likely to be the sensor ! So I've got one in the post on sale or return ! He wasn't to keen on letting me try a Speedo but I still think that's where the fault lies. I found a thread via Google about a chap who also had the same problems who managed to take the Speedo apart  he reported dry solder joints and success after resoldering the joints the main problem was unrolling the bezel without making a mess of it. He reported to return it to the manufacture was about half the price of a new one. 

[tomwood]

Interesting. My 2013 Supersport has development similar issues after its long winter rest in the garage. Dial wavers around all over the place as it approaches 80. Also been cutting out completely intermittently.

John, assuming mines the same, where is the sensor to be found and which rear wheel is it?

thanks, Tom

[tomwood]

Sorry John, just noticed you said offside wheel. I'll take a look at that.

is there any chance I might be able to trouble you for that CC guide you mention?

Tom

[JNC]

Ping me your email and I will send it

[tomwood]

Cheers John, got your message, many thanks.

[JNC]

New sensor fitted lastnight , done the light test and the light is brighter than the original one , I went out for a test drive and all looks good again ! Very steady no flickering .