I rebuilt my Sunbeam speedometer by feel since I had an extra one to
risk damage. The following is what I did. I cannot swear that this is the
best way or even the correct way to do it for my Sunbeam or any other car.
I slightly bent out the tabs of the chrome ring, using a small
screwdriver and keeping pressure on the outside edge of the chrome ring so
as to not distort it. I only bent the tabs out enough to rotate the ring
-- once the tabs line up with the slots the ring will pull off. The glass
follows.
To take off the needle, I learned the hard way by damaging one of the
guages (I tried to pry it off with a pair of screwdrivers and bent the
shaft). I found that the best way was to stick my finger in through the
light bulb hole and rest it on the metal cup that surrounds the magnet.
While holding the cup from rotating, I lightly twisted the needle and
pulled it off. I do not know what the experts do. By the way, a "cup"
may not be the exact description. It is more of a 1.75" diameter disk
with about a 1/8" lip all the way around -- as if the bottom of a can was
sawed off with part of the walls left.
After removing a couple of small screws, the face comes off -- be
carefull not to bend the "0" pin on the face. Two screws on the back of
the guage allow the mechanism to come out -- except that the adjusting rod
for the trip meter must be removed first. First, I would suggest drawing a
picture of the entire stack of springs and washers, etc. of the rod so it
can go back together properly. Second, if you push the gear on the rod
up, you will find a little pin which needs to be pulled out, invariably it
fall out and get stuck on the magnet. Third, at the top of the rod is a
circlip that pulls off and allows the entire rod to be disassembled and
removed. Then the speedo mechanism comes out.
With the mechanism out you will see two gears running off of the
single gear attached to the speedo cable mount. These two gears are
attached to metal rods running through the speedo mechanism housing to
the other end where a small cam pushes and pulls the odometer and
tripmeter levers. There is a small clip at that end which after removal
allows you to pull out the gear, rod and cam. This is what freezed up on
mine. I cleaned it and lubed it with a tube of distributor cam grease I
had (I can't say that this is the best for the application). Then I put
it all back together -- in the reverse order, as they say.
Also, there was an adjusting screw close to the top of the speedo
shaft which pushed or pulled a plate which seemed to adjust the play in
the speedo shaft, and therefore the metal disc. I thought there was too
much play so I tightened it a little. After I put it all back together
and installed it, I found that the needle stuck or would not move quickly
enough. I ended up taking off the glass and face again and reinstalled
it (with a cardboard needle stop I taped in) and ran it without the face,
adjusting that tension screw until it worked freely, without wobble, and
then put it all back together.
I guess that is just about it. Oh, one last thing. I do not know
what the proper procedure is for determining where the needle should go
on the shaft. I left it so that it rested on the "0" pin, with maybe a
very very slight pressure (for all I know any amount of pressure will
advance the deterioration of the spring). It seems to be working
correctly (or at least as close as it ever did). I understand that to
recalibrate a speedo, they replace the spring that the needle and disc
turn against to slow or speed up the rate of needle advancement (I
always thought replacing the gear at the transmission end was how it was
done -- maybe both are alternatives and it depends on availability of
parts).
Good luck.
Jay Laifman
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