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 careful 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).
Jay> To take off the needle, I learned the hard way by damaging one of the
I've had great success by just grabbing hold of that sucker (the needle) and pulling straight out, no need to reach in the light hole. Also, the stop at 0Mph is really a spring, so you don't have to be too careful. To get the correct reading when putting the needle back, I put the needle on pointing to a small white dot you will find just below 0, around -10Mph as I recall... now push straight in the stop with a small knife blade while you push the needle past. This pre-load won't hurt the spring and gives pretty accurate readings. To get better readings, I have left the glass off, driven a known speed (by the tach) and re-installed the needle at that speed.
Also, that end-float adjustment is the solution to a lot of problems, it is critical! I stick a small screwdriver in the cable hole and while rapidly spinning it, you get a feel for how the needle operation is. You need to put the needle on, but only lightly to do this. It has been suggested the kerosene is a good lube for the bearings. I know SAE30 is not! I used WD-40 last time.
I never disassemble the trip counter shaft, there is a small roll-pin that attaches the black plastic shaft, remove it and the shaft and you can just get the instrument out of the case before disassembly, then it just un-screws.
I also never bend the chrome ring, just hang on and twist. Be sure to repaint the needle and clean the glass and it will be like new!
Gary Winblad '64 Tiger '66 SV Alger San Jose