Speedometer failure----any similar experiences?

[gulf 1]

I have 2015 DURATEC,I am finding the Speedo works fine until either I stop in traffic or the weather gets hot then it flutters and dies until I get moving or the weather cools,this leads me to think the problem is heat build up somewhere but would it be the sensor or the speedo head.At the moment the sensor gap is 1mm and the led flashes on every tooth of the gear wheel.If anyone  has any thoughts I would be very grateful.

[Jonathan Kay]

Workshop Notice 572 describes how to modify the wiring to improve reliability. Please send me a Private Mail with your email address if you'd like a copy.

Jonathan

[gulf 1]

Hi Jonathan have sent a pm not sure if you received it as it says your mailbox is full.

Dave

[Jonathan Kay]

Sorry.

Workshop Notice sent. Credit to John Vine on this.

Jonathan

[ScottR400D]

My speedo would ‘drop out’ at highish speeds, 90/100 mph or so. 

The gap was about 1mm and flashed on every tooth. 

Moved it to 0.8/9mm and it’s been fine since. 

Flashing when turning the hub isn’t a sure sign that all is well IME. 

[sjl1]

Happened on my 2017 duratec on saturday, speedo dropped to zero, flickered about and recovered by time returned home, another chore to investigate, assume its sensor on driveshaft

[John Vine]

...assume its sensor on driveshaft

Sounds like the sensor air-gap is either too big or too small. 

I guess that a 2017 car will already have the WN572 earthing mod fitted by the factory? 

Also that it will have this sensor (300A0019A)?  Or possibly this one (CAT-SP-0038AK)? 

Perhaps you could confirm?

JV

[sjl1]

Will take a look tonight ans try and post a photo

[gulf 1]

I have been playing around with different sensor gaps today,originally the gap was 1mm and the Speedo worked fine until stopped in traffic or the weather was hot when the Speedo fluttered or died until it cooled.Dropped the gap to 0.8mm   the led was on all the time,opened up to 0,8-0.85 but Speedo flickered at 30 mph increased gap to 0.9-0.95 and the Speedo works fine.Not been stuck in traffic and not too hot today so I am not holding my breathe that it's fixed.The variation in the gap at any one setting is down to the gear wheel run out.Not sure what happens if the gap is larger than 1mm, I think it was over that when the problem 1st  arose ,in my ignorance I never checked the gap before reducing it.Not sure if increasing the gap will help.

[oldboarder]

For info: Just checked my 2017 Kit built 310S SV.  The workshop note does not seem to have been implemented.

The new "tamiya style build manual shows a slightly different routing of the cable to previous editions.

I seem to have the REAR WHEELSPEED SENSOR - 2017 reference: 300A0019A

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My speedo played up for about 30 minutes last week but has been ok since a stop & engine restart. However I now notice my rev counter , although on zero when ignition off, does not read below 1000 rpm seems to be ok above these figures.

[John Vine]

AFAIK, this is the spec of the pre-2017 sensor. It suggests a max air gap of 2.5mm.

The 2017 Assembly Guide says:

"Remove the outer locknut from the speed sensor. Pass the speed sensor through the bracket and replace the locknut ensuring that the serrated face is against the bracket. Adjust the two locknuts until there is a 1 mm clearance between the sensor and the serrated disc on the driveshaft (this is only an approximate clearance you may have to move the sensor out to get a Speedo reading). Tighten the locknuts without disturbing this clearance. Refer figure 133 or 134 as appropriate."

So the best result could well be in the 1.00-2.00mm range.

JV

[John Vine]

... until stopped in traffic...

What happened then, exactly?  I'd have expected the speedo to drop to zero and stay there.

JV

[John Vine]

The workshop note does not seem to have been implemented.

That's interesting.  Perhaps CC have incorporated the improved earthing circuit in a different way? 

For info, the original WN572 was dated 11/06/14, and marked as issued to "Production, Service and Agents".

JV

[oldboarder]

The car has only done 300 miles so I'll try & last until its 1000 mile service which I intend to use Bookatrack for. Could do this myself but lets see what they say !

[gulf 1]

Hi John

The Speedo was working fine until I stopped when it seems like there is a heat build up as when carrying on after the Speedo jumps around until it seems like it cools then works fine again.Also on a trip to Portugal last year the Speedo was working fine until the temperature rose to 25C ,then the Speedo was jumping around while driving and at 28+ it stopped working altogether until the temperature dropped then it worked fine again,this happened many times while there.During the cooler months there has been no problem.I am wondering whether the gap needs to be larger to allow for possibly expansion of the trigger wheel with the heat.

[John Vine]

Very odd!  I doubt the trigger wheel (aka reluctor ring) would expand significantly.  You could try increasing the gap to around 1.5mm.

Maybe it's not the sensor or air-gap at all, but a poor circuit somewhere?  I'm thinking of things like dry joints or loose connectors.  Or, of course, a duff speedo.

What year and model is your car, and which speedo do you have?

JV

[gulf 1]

Hi John

The car is a 2015 supersport R 2.0l duratec with a caerbont Speedo head.As you say increasing the gap will be my next step,will have to wait for the weather to warm up now.If that yields no rewards then the wiring will be the next thing to inspect.

[John Vine]

Out of interest, is the speedo this one (MY2015) or this one (2005-2015)?

JV
 

[gulf 1]

Not sure which Speedo the only identification I can find are the numbers

71255SM and EE-S33-1B32-16B  which way just be serial numbers.

Dave 

[gulf 1]

Just looked again and the Speedo is the(2005-2015) version.

Dave

[Blacken]

Having made the trip at the weekend from West London to Stoneleigh and back again and only clocking 40 miles on the odometer, l paid a visit to Nick Potter on my trip up to Scotland.

His mechanics quickly raised the car on the inspection ramp and had a look.

They adjusted the gap on the sensor to about 1mm. Nick said that the gap is often too small which can become a problem in hot weather.

Nick runs a nice operation and has a good pair of mechanics on hand. He was able to look at my car at short notice and dealt with the problem with the minimum of fuss. Top bloke!