The edit to this post is to update info now that I have completed the reassembly of the speedo. A few things changed from my original plan so I am editting those sections so the article reflects the final process and suggestions.
The speedo on my '67 CL77 worked fine, but the face had a strange dark pattern on it and the number 1 on the 10K odo wheel was almost all black. I thought that perhaps the face was faded and for some reason faded unevenly and the odo wheel numbers were deteriorating. The screws that held the face tight were a bit loose and the face would vibrate just a little when the bike ran. I was going to look for a place to send it out, but read all the various speedo threads here (especially Gman's, THANKS!) and with monsoon type rains falling today, figured it was a good day to go in the shop and play with the speedo. Here's what I encountered as I took it apart.
Bezel removal was done slow and easy as Gman recommends. Started with a small fine tip screw driver and worked my way up to a wider blade. I did have to insert a small flat screw driver between the bezel and body of the speedo and slightly pry to get the two separated. Obviously, the factory sealing was still fully intact.
With the bezel off, the glass, inner trim bezel (with nippon seiki on it) were still sealed to the speedo body. I used a razor blade between the flange on the body and the inner trim bezel and slowly separated the two. A paper gasket is between that inner bezel and the body flange and it is apparently glued to both surfaces in the assembly process.
The glass lens was still sealed to the inner bezel. In hindsight, I should have left it that way. But I wanted to thoroughly clean the glass and the inner bezel was thought to be in the way. Probably could have done it with it still attached to the glass. I cut the inner bezel away from the lens with a razor blade inserted between the two. Be careful. Don't cut yourself or scratch the paint on the bezel. My suggestion is if it is sealed well, leave it be and clean it with the two pieces attached to each other.
Once separated, I took a look at everything in prep for cleaning. What I found was somebody had shot either powdered graphite or moly coat in thru the drive hub and that was what made that funky dark pattern on the face. It all washed off with Dawn and water using a soft tooth brush. I used a tooth brush so I would not get any non-uniform patterns on the old paint.
Indicator needle was removed by prying with two screw drivers. I suggest you put the speedo frame in a vise to do this. Then rest the screw drivers on the two screws holding the face to the frame and lightly pry on the needle. It should pop right off.
Now to reseal you need to do things in the proper order. It appears that the factory had a soft rubber gasket that held the lens centered, spaced it properly from the inner bezel and sealed everything on that side of the inner bezel. The paper gasket between the back side of the inner bezel and the flange on the body seals the rest.
The order of assembly was as follows.
Cut a rubberized gasket (matierial available at NAPA) to go between the front surface of the inner bezel and the lens. Thickness of this gasket is 1/16". This gasket is very difficult to cut accurately so it does not show when the speedo is assembled. I used the NAPA gasket because the same rubberized gasket from Pep Boys was white and black. The NAPA gasket is black. It is visible thru the glass so black gasket is the way to go.
I first mounted the gasket to the flange on the inner bezel using contact cement. You could use High Tack, I just did not have any and was not making another trip to the store. Once this gasket is properly positioned, put the glass on top and slip the stainless bezel over it all to make sure everything looks right. The gasket should not be sticking out anywhere in view under the lens.
Clean the lens on both sides with a paper towel soaked in alcohol. It should be squeaky clean.
Using Permatex Super Black RTV gasket, which is the same gray as the face, I installed the lens to the gasket on the inner bezel. Make sure the lens is centered. With the applicator nozzle cut for the smallest hole, put a small bead of RTV around the OD of the lens and gasket (see diagram). This should be a small fillet of RTV. Idea is to secure the lens. Let it dry for an hour. Once dry run a similar fillet of RTV on the OD of the gasket, sealing it to the flange of the inner bezel (see diagram). Don't worry if you get some on the lens. You can trim it off later with a razor blade and clean with alcohol.
When this dries, you will have a lens/inner bezel assembly. Trim any RTV that smeared on the lens with a razor blade and paper towel dampened with alcohol. It is ready to install on the body of the speedo.
Cut another gasket that is the OD of the speedo body flange and with an 3/16" width. That means it will be 3/8" smaller on the OD. Make sure it fits inside the outer stainless bezel and fit everything up dry to check all is well.
Now, put a coat of High Tack on one side of the gasket, or if you don't have it, a coating of contact cement on the flange of the inner bezel. Mount the gasket. Let it dry. Don't use the contact cement as recommended in the directions. Put it on and on surface and then immediately install the gasket. It allows you to position it. It will dry fine in a few minutes. Once that is dry, put another coat of contact cement on the other side of the mounted gasket and attached the inner bezel/lens assembly to the body of the speedo. Make sure the glass is clean on the inside because this is your last chance to get it right. When you position the assembly, put the speedo body in a vise and this way you will have two hands to make sure the inner bezel is properly aligned with the face of the speedo.
Once this dries, you are ready to install the outer bezel. First try it on the assembled body/lens. The inner edge of the outer bezel should rest on the glass. If it does not, you have to trim some of the RTV from the front of the lens/inner bezel. Another trick is to index the bezel while watching for it to lay flat on the glass. I found my had a position it liked better than others.
Now, put a liberal bead (no applicator here, just the tube mouth) of RTV all around the inner recesses of the outer bezel. Idea is to have it extruded out onto the lens and out the back where it will get crimped onto the flange of the speedo body when you put the two together. I put a mark on the outer bezel with a marker and a mating mark on the body for that sweet spot mentioned above to make alignment easier.
Now, the the outer bezel top surface facing down on a paper towel, insert the body assembly into it and push it down until RTV is forced out. It makes a mess, but don't worry about it. While holding downward pressure on the body, start to crimp the outer bezel over the body flange with a screw driver or your tool of choice. I actually used a small nylon hammer. Get at least 4 points crimped (12, 3, 6 and 9 o'clock) and check to make sure the bezel is touching the lens. You can wipe off some RTV now if you wish. But the primary task here is to put it back on the bench and finish crimping the bezel to the body. When the crimping was 99% done, I used a ball peen hammer as a forming tool to press on the crimp. I also went around and lightly tapped the crimp flat to a uniform flat look. No ham fisted hammering here!!
Now you can wipe off the RTV. Alcohol does a great job on a paper towel. Make sure to get it all off the lens. Just wipe it flush around the crimp area since it is sealing it there as well.
Last step is to glue the rubber vibration ring and mounting ring assembly back to the body of the speedo. I first made sure it was properly oriented and marked both pieces with a pencil with alignment lines. Then using a liberal amount of contact cement, I installed the rubber ring on the speedo body with the glue still wet to allow positioning. I then set it in my vise, with the mounting ring resting on the jaws of the vise, put a piece of plywood on the bezel and then about 20 lbs of weight and left it that way for the glue to dry.
I realize this is difficult to envision by reading, so I've made a cross sectional diagram and included it here. Note that I've put spaces between everything just so it is clear which is which. Obviously, there should be no space between sealants and surfaces they are sealing.
Lubing and servicing the internals have been discussed in the referenced threads. So no need to repeat here.
Hope this helps the next guy.
regards,
Rob
CL Speedometer RebuildCL Speedometer Rebuild
Snakeoil
I somehow missed this post. Excellent diagram and instructions. You can reset the odometer while you're inside there, if you need to. None of my speedos belong to the bikes I am restoring so I may reset them. http://www.flickr.com/photos/63154743@N ... 068179860/ G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
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