Speedometer reading 35mph at 70mph??

[SteveyP]

Hi all

Once again need some advice please. Driving back from Essex I noticed that the seemingly good speedometer would only go up as high as 35 mph (tops). Bearing in mind I was on the M4 at the time, then I must have been going faster than this at some points.

Any ideas? Do I need a new speedometer? The rest of the dials and warning lights work (I can't say they all work well as the fuel guage reads either completey full, or half empty - I know that is the sender unit though). Everything else 'appears' ok.

Anyone had a similar issue before?

Steve

[Rich Hanlon]

Hi Steve, before I pulled out the starter I would check that neither of the drive cables are kinked,(wheel to lambda-counter or lambda-counter to speedo).

After that i might take off the front wheel and have a look at the state of the plastic cap that fits inside the NS wheel to drive the speedo cable - if the centre of that has rounded off it might be slipping in there rather than driving the speedo.

Next - the famous angle drive?!

[SteveyP]

Thanks for that Rich.

I did think dust cover and/or angle drive originally, but then Chris N thought it could also be a new circuit board required or even a new speedometer job.

I shall start with the basics and work from there then.

Thanks
Steve

[MikeWard]

Steve,

It sounds the same as mine - mine works up to 30mph, sticks between 30mph and 40mph, then will work up to around 55-60mph and won't go any higher.

For reference, my car has had a new angle drive, and lower cable which admittedly were somewhat worn (counter box and upper cable are fine).

Having recently had the binnacle off the car I tested the speedo using a drill and it is still sticking in the same spots - which unfortunately means new speedo. However before I go there, I put a call into Speedograph recently and they have advised me that they may be able to repair/service the speedo head - I need to send it into them to check it over. Will let you know how that goes if you like.

Unfortunately if they can't fix it, then I'll need to stump up for a new one from DMC.

[stunned_monkey]

It isn't that complex, have you tried simply lubing it?

[SteveyP]

All

Thanks for the responses. Mike let me know how you get on with that refurb at Speedograph will you? If no good then buying a new one is an expensive option for the future. Think I'd prefer to have the the actual speedo working than a new digital unit or something.

Steve

[MikeWard]

stunned_monkey Wrote:It isn't that complex, have you tried simply lubing it?

Martin, was that aimed at my response re the speedo head?

SteveyP Wrote:All

Thanks for the responses. Mike let me know how you get on with that refurb at Speedograph will you? If no good then buying a new one is an expensive option for the future. Think I'd prefer to have the the actual speedo working than a new digital unit or something.

Steve

Will do Steve, no problem. P.S. nothing wrong with a GPS digital backup

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[stunned_monkey]

As others have said the angle drive either works or it doesn’t. The speedo head though is a simepl as it gets with a spinning magnet dragging round the needle on a very weak spring. I can’t see how that would get stuck in particular positions unless the pivot itself needed a bit of lubing.

One simple option to check is the drive cap on the front wheel. I’ve had to wrap a layer of insulating tape around a couple of them in the past in order to get a tighter fit in the hub.