| 51f1 | -- 11-23-2009 @ 5:18 PM |
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Why does my 1951 truck speedometer pointer bounce? I have a NOS speedometer The pointer bounces below 25 mph. The slower, the more it bounces. Above 25 mph it is rock solid smooth. Richard This message was edited by 51f1 on 11-23-09 @ 5:21 PM
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| 40guy | -- 11-23-2009 @ 5:36 PM |
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This is common with old speedometers. The bounce at low speeds is due to the fact that the speedometer has spent most of its life in this range and the internal components are more worn in this area than others i.e. higher speeds. I have never known the bounce to be a problem and the only remedy is probably a complete rebuild with new gears etc. However; I just let em bounce.
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| carcrazy | -- 11-23-2009 @ 7:37 PM |
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You might want to try lubricating the speedometer cable. Pull out the inner cable and if it is frayed, replace it.
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| 51f1 | -- 11-24-2009 @ 2:08 AM |
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The cable and the speedometer are new. I have pulled the cable and lubricated it. There shouldn't be any wear on either. Richard
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| mvillebob | -- 11-24-2009 @ 12:36 PM |
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Richard, The lube should help. Also, make sure there are no sharp turns in the cable housing. Lets us know what happens with the lube. Best,
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| 37RAGTOPMAN | -- 11-24-2009 @ 4:58 PM |
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Make sure you use GRAPHITE LUBE on the cable, you could also remove the speedo and use a drill and lube the drive unit when the speedo is upside down, do this very carefully, [ make sure you are going in the right direction ] ,I have freed up quite a few speedo using this process, it might be in the shaft,that come out of the back. make a square drive from a old scewdriver,and a grinder, and see if the shaft coming out of the speedo is hard to turn, if it is a few drops of oil might free it up, hope this helps 37RAGTOPMAN LETS HEAR HOW YOU MADE OUT,,,
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| tudorbilll | -- 11-24-2009 @ 11:24 PM |
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You can buy the fluid and fill it yourself.Comes whith instructions. I did mine about 15 yrs ago.Be carful taking it dont break it. its not a fun place to work they never are. Get a trouble lite and take a look.the air in that little line is pushed buy the gas in the tank.more gas more push. the air in the line in turn pushes the fluid up in the tube. Even when your done I would keep track of miles I drive.After a fillup you can go about 150 miles,you have a 14 gal tank so you drive on about 10--11 gal.
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| supereal | -- 11-25-2009 @ 6:00 AM |
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As the cable is new, be sure it isn't just a small bit too long. If it is, it will cause needle jumping from being jammed in the sheath and/or at one end or the other.
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| 51f1 | -- 11-25-2009 @ 7:29 AM |
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Why does this problem occur only below 25-30 mph? I installed the NOS speedometer and a new replacementcable over a year ago. I haven't devoted my full time to this problem as it is part of a long-time body-off total restoration of my truck, which I just finished with the installation of a new bed. When I installed the cable, I felt that the inner cable was a bit long and ground off some of the speedometer end. I later loosened (backed off) the attachments on both ends in case that was forcing the cable too far in and causing binding. Those two actions seemed to help by confining the bouncing to below 25-30 mph. I think that I will connect my drill motor to the lower end and spin the cable to see what happens. If the speedometer works o.k., that means it may be a problem with the drive gears (unlikely) or the Chinese inner cable is still too long (more likely). But why does the problem occur only below 25-30 mph? Anymore ideas? Richard
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| JebNY | -- 11-25-2009 @ 6:04 PM |
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Turning slower the resistance is allowing it to grab. Jim... 1950 F1 Stake
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| supereal | -- 11-25-2009 @ 6:17 PM |
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Even though the speedometer is NOS, that doesn't mean it is OK. Many instruments were replaced at dealers when they had problems in new cars, and were put back on the shelf. I bought a NOS clock for my '47, and it was delivered in an original box. It was beautiful, but didn't run. I've fixed several of these, so I took it apart and found that the winding coil points were burned. I fixed it, and it now runs fine, but I know it had been used in a car sometime. I had hoped that a $250 clock would actually be NEW old stock. When speedos jump, it can involve either the body of the thing where the shaft enters, or the gap between the disks. Even it is truly NOS, I'd suspect it needs cleaning and lubrication.
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| 51f1 | -- 11-26-2009 @ 4:41 AM |
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I have the same impression of NOS stuff, especially if the box has been opened. The reason some of it's still around is it was found defective and put back on the shelf. I have a NOS Ford windshield washer that had obviously been removed from it's box. The check valve that fits into the reservoir cap was defective. A bit of epoxy fixed that. But this NOS speedometer was never removed from it's box before I got it. Thanks, everyone, for your advice. Richard
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| trjford8 | -- 11-26-2009 @ 8:23 AM |
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Richard, this speedo sat on the shelf for for over 50 years. The grease(lube) in the speedo has probably solidified or become very sticky by now. If you have ever encountered an old can of grease that has been around this long you will see that it is very sticky and the lubrication qualities are less than desireable.Your speedometer, even though in the box, was exposed to air and a variety of temperatures.This causes the lube to coagulate(sticky) and this is probably the source of the needle bounce.
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| 51f1 | -- 11-26-2009 @ 10:41 AM |
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But I lubricated it! Richard
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| trjford8 | -- 11-26-2009 @ 12:07 PM |
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Rich, lubricating it does not remove the old grease and may or may not soften it up.
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| supereal | -- 11-26-2009 @ 2:33 PM |
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Speedometers are like clocks. They need periodic cleaning and lubrication. They were not made to last 50 or more years, in any case. If they were, they would have been designed with bearings in the housing.
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| 51f1 | -- 12-03-2009 @ 1:45 PM |
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Well guys, we must have frightened my speedometer with all this discussion. With 2,050 miles on it, it decided to quit bouncing below 25 mph. Now it's rock solid throughout it's range. I give up. I have no clue. Richard This message was edited by 51f1 on 12-3-09 @ 1:46 PM
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| supereal | -- 12-03-2009 @ 2:22 PM |
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I'd go along with Tom's observation. It is likely that driving loosened up some hardened grease. Most speedos that bounce do so more often as the temperature drops. I have a very long cable in my '47 that reaches back to the overdrive on the rear axle. It, too, starts to jiggle a bit when the temps drop.
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| 51f1 | -- 12-04-2009 @ 4:26 AM |
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The temperature here recently dropped into the 40s. That's when the bouncing stopped. I attributed it to the cool weather. It warmed up, but the bouncing didn't return. Like I said, I have no clue. Richard
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| alanwoodieman | -- 12-04-2009 @ 9:41 AM |
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had a similar problem with a 57 x-brand auto, there was a small hole in the back/bottom of the speedo case, shot a little WD40 in the hole and it worked like a charm, as I suspected the grease was hard
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| JebNY | -- 12-04-2009 @ 2:04 PM |
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Never had it happen to me but I have heard of problems using WD40 on speedometers and clocks. It works for awhile then gums up worse than before. You need to clean the mechanism out the best you can and then use a light oil like they use on sewing machines. Jim... 1950 F1 Stake
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| Stroker | -- 12-04-2009 @ 2:56 PM |
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I've used a lot of "snake oil" in my day, and WD-40 we have to remember was only intended to be a Water Displacing product. I have a couple of favorites that I have come to rely upon as solvent/lubricants: Aero Kroil is expensive, but a pretty decent product that creeps well into little spaces, and leaves a little lube behind without a gum residue. My "homebrew" is simply 50% hydraulic fluid (not brake fluid), and 50% acetone. I'm also a fan of Marvel Mystery Oil, and I've found that if you are lubing really delicate stuff, it works well with the 50% acetone thinner mentioned above. For sticky starter Bendix drives, I've had really good luck with "Dri-Slide", which is mainly sold in gun shops. There used to be an aerosol product called "Tri- Flon", which was Teflon-based, but I haven't seen it for a few years.
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| supereal | -- 12-05-2009 @ 10:53 AM |
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Starter drives should be kept absolutely dry, without any lube, as it tends to accumulate enough grime to cause the drive to stick. WD40 is as much solvent as lubricant. Its best quality is that it takes a long time for it to evaporate and/or harden. It can be used to oil clocks, etc, by squirting some into the cap, or other container, then apply it to the pivots with the point of a toothpick dipped into the stuff. If you just spray it over the works, it may free it up, but eventually will require a solvent bath to get it clean.
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