Bill,
I've been doing a LOT of work on my speedo lately, and I've learned a lot about
them. The needle is driven by a flat disk that is in turn driven by a spinning
magnet--i.e. magnetic coupling--driven by the cable. The needle shaft is
(apparently) hardened steel that sits on brass 'bearings' (actually, just holes
in brass fittings). A light, concentric, watch-type spring resists the magnetic
driving force and should return the needle to its stop.
I can only speculate, but some possibilities are (since your odometer is still
working):
- something has gotten stuck in the needle mechanism; possibly between the
driven disk and its housing
- the needle pointer has some loose from the needle shaft (it's just a press
fit)
- the spring is broken or has come loose from its moorings (would probably
cause the speedo to read VERY high, and needle to not return)
- something has gotten stuck in or gunked-up the brass holes where the needle
shaft rides
Getting the speedo apart is not too difficult; you have to remove the tripmeter
reset knob (small roll pin), unscrew two screws in the back, remove the glass
cover, needle and faceplate, and it helps to remove the housing for the high
beam indicator. Then, the mechanism can be gently canted to remove.
The car's polarity is not an issue.
Bob
----- Original Message -----
From: "William Woollen" <deckhand42@hotmail.com>
To: healeys@autox.team.net
Sent: Tuesday, June 2, 2009 10:05:47 AM GMT -08:00 US/Canada Pacific
Subject: [Healeys] Speedometer question
Greetings Listers,
I confess to being a lurker but now have a problem that someone may have
encountered before.
After a short drive last weekend, my speedometer needle started to hang up and
would not return to zero. The odometer still seems to be counting properly.
I have a 1965 BJ-8 that has been converted to negative earth.
Any help would be appreciated.
Best Reqards,
Bill WoollenHBJ8L29101
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