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odometer or speedo fault?


lavena

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POBC.

 

Am still running in, or so I thought. Went for a long run today - not my normal home work home. Did about 100kms at a fairly constant speed - mostly motorway speeds.

 

Although the trip is approx 100km my speedo says I only travelled 25kms!

 

I know the speedo works - I calibrated it and checked it so when I am doing 100km/hr that is the speed I am doing.

 

The needle does occasionally wobble so I guessd the oddometer could also "miss a beat". However, a 75% under reading is very significant - could it still be a fault with the sensor or a more fundamental problem?

 

Andy

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The sensor may not be faulty. Try checking the air gap between the sensor and the reluctor ring. IME, the gap setting is crucial for reliable speedo operation. Although the Assembly Guide suggests 1mm, I found that something nearer 0.3mm worked much better. With the ignition on, turn the driveshaft tooth by tooth while adjusting the sensor gap. When the gap is correct, the sensor LED will light up as each tooth passes.

 

JV

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That was my thought - but today I could sit at 100km/h for 5-6 minutes with the needle really steady and still only go 2-3km (rather than 8-10)!!!

 

Still will fiddle with the sensor - it does have a little jiggle, especially at 70km/hr! Also odd that 100km/hr is rock solid.

 

Andy

 

RoadSport 175 SV

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Fitted the new probe, set it at .4mm, LED flashes and speedo needle moves when hub is turned by hand. Also changed all the rear wing set screws for plastic ones. Araldited washers to the two lower Dzus fasteners, to make them into home made wing nuts (thanks for the tip Paul)

While up on stands had a quick look underneath. Small oil leak from gearbox/propshaht seal ☹️ Bugger

 

 

 

 

www.peters7.co.uk

 

 

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  • 3 months later...

Speedo now works well at showing speed, Somerset and back over the weekend, very consistant with Sat Nav, however for every 10 miles covered by the Sat Nav the odometer recorded only 7. Can't multi task, drive, listen to "Senior Management" complain about the cold draughts AND do mental arithmatic all at the same time. Is there a solution?

 

Edited by - Domus on 8 Mar 2011 23:37:24

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I checked my odometer out this weekend after seeing this post and it is also under reading by a significant amount! Read 79 miles for a round trip to Goodwood which is 55 miles away and I took a few detours! Speed indication is about right.

 

Has anyone spoken to CC about this? Good for the insurance I guess but not for the mpg calculations!? I am at the factory on Friday to swap over my exhaust - I will speak to them about it then.

 

Edited by - Garth on 8 Mar 2011 20:13:42

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As per John's suggestion I fiddled with the sensor gap.

 

Essentially I got it as small as possible - if you put it up on stands you can rotate the wheel and there is a little LED on the top of the sensor that flashes. Mine was not seeing all the teeth with it set as per the manual. With a smaller gap - no problem - all teeth register.

 

Now the speedo and oddometer work and are consistent with each other. I did recalibrate the speedo as it was slightly off after the adjustment.

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Hi Domus,

 

I found that my odo would under-read by 25-30% even though the speedo needle gave a steady speed reading (usually about 5% optimistic compared to the satnav and Road Angel). Your gap setting of 0.4mm is about ideal IME.

 

A couple of things worth checking (I can't offer any suggestions about Senior Management though 😬):

 

Are the teeth and sensor tip thoroughly clean? Does the reluctor ring run true through a full 360-deg rotation? I found my reluctor ring was running out-of-true by up to 0.3mm diametrically.

 

JV

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