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From: Ian Howell
Fromemail: javelin_technical_services@msn.com
Category: Technical
Remote Name: 81.178.77.240
Date: 07 Feb 2006
Time: 07:58:21
Rob: - It sounds like general dirt on the needle bearings. They are simply sharp points that run in 'jewel' type bearings, as in clockwork clocks. The whole mechanism is pretty simple - a magnet mounted on a circular plate is revolved by the speedo cable and 'drags' with it, against the action of a hairspring, the spring-loaded disc with the speedo needle attached. The faster the cable turns the further round the scale the needle is dragged. A good clean may sort things out. Do you have access to a local clockmaker? They usually have an ultrasonic cleaning bath which 'shakes off' the dirt in a bath of solvent. Not usually expensive. It is a fiddly job, but it is possible to clean these yourself - but there is a grave risk of damage to the hairspring. Avoid using special lubricants as the bearings are meant to run 'dry' and the residues will only collect dirt. Hope this may help. Regards Ian H