I'm working on my speedometer out of my 50 model truck right now. The needle moves freely, but the drive part, that the cable turns is gummed up and works real stiff. What's a good thing to do to loosen the mechanism up? Lubes, penetrating oils...?
or mineral spirits (paint thinner) don't get it on the needle or face or odometer or you'll be painting them again. I put speedo cable lube on mine when I did it a decade ago. it got "sticky" again and started bouncing so I have to do it again, but mines not in a sealed case at all so it might just be all that Mojave Desert road in their messin it up.
Here's my speedo repair technique: remove bezel and glass, get speedo out of case. Get a tin can or something that allows you to set the speedo down with face up and secure balance, and study how you are going to hold the thing so neither your fingers nor the liquids to be used can touch the face or odometer. That stuff is VERY delicate and easy to destroy. Near the cable end, on what amounts to the speedo's main bearing, is a tiny brass plug. Get it out--I usually manage to extract them unhurt by threading a tiny machine screw into the cup--and extract the piece of felt within. I then repeatedly flood this lube well with first kroil then WD40 as it frees up, sometimes liquid wrench if I feel something thinner is needed. You want lots of fluid to go in there and then leak out the bottom to dissolve and wash out the petrified lubricant and crud. When the shaft will spin freely by finger twirl--you should be able to get 5-10MPH easily by finger--soak several times with carb cleaner and then brake cleaner to remove all those miracle solvents. When drained and dry, I fillerup with Marvel Mystery Oil, based on my scientific observation that the only real speedo tech I ever saw in action used something that sure looked like MMO. The multiple screwdriver tip sets you can get at discount stores contain a Canadian Robertson tip (square) that fits early Ford speedos and allows you to motor them up. You can also do a very rough test based on the supposed RPM of your elecric tool, based on the speedo's calibration of 1,000 RPM=60 MPH. Here's a ratio test page: http://www.speedometershop.com/rep-pag.htm
Great. I have it apart and I see the little brass plug, so no problems there..... what is kroil and where do I get it?
Only comment I can offer is CAREFUL winding up that speedo with your electric drill. Here in Canada we've got zillions of square drive (Robertson) bits for screwdrivers and drills. Work great to spin up speedos, BUT, make sure you've already got it cleaned up and lubed. Although the speedo part is basically a magnetic cup (attracting the spung wound needle), the odometer is mechanically gear driven directly off the input shaft. Spin that sucker too fast, with sticky odo gears, and you can strip off odo teeth before you even think about it!!! Ask me how I know!!!
Interesting. How do you crimp the bezel back over the body of the speedo when you're ready to put it back together?
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