Erratic Speedo

[Fil M]

Hello All, I have read some of the posts to do with speedo problems. Mine is a bit different. It works fine ..... but only after the first mile or so. If i start the car up the needle pings up to read 60mph (for example) and sticks there .... Im still stationary!! On driving off it drops to zero, pops backup and sticks on another speed begins to behave itself and then sticks again etc. It settles a mile or so down the road and behaves for the rest of the journey. When it behaves I believe it to be accurate.

Thanks again.

[Stationary M25 Traveller]

Is it new and electronic or old and cable driven ?

[charlie_pank]

I think your speedo drive is about to die as mine did. Rather than getting the gearbox out and fitting a new cog, I chose to install a bike speedo. I'm sure there are instructions on BC here somewhere.

 

back here because I want to be.

[Fil M]

It is electronic ... 2001 car .... It could be at the speedo dial end of things ... I tapped the glass and the needle moved to a new position .... I am puzzled by its needle moving on starting up before the wheels turn. I am wondering if this takes the sensor on the wheel out of the equation.I have seen this mentioned in other ''chat entries' I should have mentioned electronic in the first message. There is no thick cable in the centre of the back of the unit. Thanks

[sjmmarsh]

Sounds like it may be sticking. My speedo and rev counter blip when the car is turned on, but return to zero afterwards.

 

Is the mileometer tracking the right distance or is it sticking too? You could borrow a gps system to check this.

 

Steve

 

Steve Marsh

My Caterham Page

 

[Fil M]

Hello sjmmarsh,

Yes I have a sat nav so can check against it. When the weather and salty roads allow i will take her out and check. What did you do to unstick yours?

[sjmmarsh]

Fil M

 

Mine wasn't sticking - but it sounds from your description as if yours might be.

 

My (simple) understanding of the way the speedo works is that it measures pulses from the speedo drive in the gearbox and the faster the pulses, the greater the indicated speed. These same pulses also drive the odometer reading.

 

If your needle is sticking for some reason, you should find that the odometer reading is still correct, even though the indicated speed is all over the place.

 

I don't know what would make it stick though.

 

Steve

[Fil M]

Thanks again Steve,

 

Because of its erratic nature I wondered about a bad connection but couldnt feel any looseness in the plug in lead unit at the back .... however I have found that the two screws/bolts that secure the speedo unit were loose ... if these act as an earth for the unit it could be these are the cause. I have finger tightened them and now await a weather window to test. We have a good covering of snow here but expect it to clear over the weekend so Monday may be my chance. I will post any results. Thanks again.

 

Fil

[sjmmarsh]

Fil

 

I hope it works for you. Let us know when you next get out.

 

Steve

 

Steve Marsh

My Caterham Page

 

[Fil M]

the snow cleared and the rain got rid of some of the salt and the cold breeze dried the road .... so out I went. After tightening up the securing nuts I saw that in the first 300 yards or so the needle sat at zero. The odometer was working though ... the tenths were counting correctly. One light tap on the dial and that was it ... working! It must just be sticking at initial start up for some reason. It condensates in colder air so this could be a link. The next tweak will be to carefully make some breather holes in its casing to let the damp out... at least i know its not at the complicated hard to reach end!!! phew.