Bouncy Speedo`

[Fer]

Hi Folks,
the car I am looking to buy has a bouncy speedo. When I took it for a test drive, it had a habit of reading between 20 and 30, whilst driving along. This is not only disconcerting, but kind of licence threatening too.

Any ideas what the cause is, or more importantly what the fix is.

[docevi1]

most of the cars I've driven do this. The Speedo cable on the Westie will probably be a mechanical unit running from the gearbox to the back of the speedo unit. Could be a knackered cable / pickup or worn speedo unit. Not that expensive bits wise (cables ~ £20, rebuild speedo uni ~ £100), but fitting will be a swine and if the trouble is in the 'box, well good excuse for you to change it

As for licence threatening, use the RPM of the car - you can get the cars speed quite accurately from the RPM since when the clutch is engaged everything is connected. The other thing with these cars is the engine note/exhaust. You soon get used to hearing speeds from the exhaust note in the various gears and it makes it easier to cruise at 30mph as you can hear when the engine note changes.

[Mutant Rat]

Quite often, it's the speedo cable binding inside its sheath.

Disconnect the cable from the back of the speedo and withdraw the inner cable. You'll probably find it is covered with dry, grey gunge. Spray with WD40, wipe clean with an oily rag, lightly oil the cable and reinsert it in the sheath, making sure it is carefully fed all the way back down to that it engages with the drive at the gearbox end. Reconnect the speedo head, and you should find it is much improved!

[flossythepig]

Mutant Rat said:

Quite often, it's the speedo cable binding inside its sheath.

It may also be an indication of imminent breaking of the cable. That happened in my Midas, the cable came out of the crashed donor (3000 mile only).

Hugh

[Fer]

Thanks for the advice, as luck would have it, the builder of the car had worked out the rpm/gear/speed and had a nice little card. I am now a dab hand at my 550 times table!