Speedometer needle bouncing

[LeRoy]

Hey y'all

 

I recently put together a 1947 d24, during the install I took the center cable out of the speedometer cleaned it, shot a little wd40 through the sheath, greased the cable and put it all back together. Now my needle bounces 5 mph above and below the speed I think I'm traveling. Other than being really dirty the cable and outer sheath seemed to be fine. Any ideas?

Thanks Andy

 

[Dan Hiebert]

If you used "regular" grease, it is too thick, and makes the needle bounce.  Although extremely messy if you aren't super careful, graphite lubricant is probably best for speedometer cables.     

[LeRoy]

I used some spray white lithium grease 

[OUTFXD]

I suggest Dry Silicone.  and dont spray it on the cable but into the speedometer via the speed cable port.

[nonstop]

There is also a wick that is on the back of the speedometer.  It comes out near where the cable screws in.  The ones in mine were dry.  I soaked them in light oil, and that stopped the needles from bouncing.

[rallyace]

The bouncing comes from either binding of the cable or one of the magnets inside the speedo unit either losing its magnetism or is missing. More often than not, it is in the speedo cable. You are dealing with a 75+ year old part here and it will need a little TLC to get it working properly. If you used a grease, your best solution is to remove the drive inner cable and thoroughly clean it and lube it with a graphite lube. You can also use a very light oil like 3 in 1, but beware, it will very likely loosen any old lube in the sheath and your problem will probably return. Sometimes it is easiest to remove the entire cable assembly and thoroughly clean out all of the old lube that is in it, relube it and reinstall it. Grease, as was mentioned before, it is too thick and will cause bouncing. The best lube is a graphite lube. Messy but it works the best. Good luck with your repair.

[Sniper]

They make a graphite based lube specifically designed for speedometer cables.  DORMAN 03344 for example

 

 

[keithb7]

My speedo bounces too. I removed my cable assy. It Spun nice and smoothly in its casing. I lubed it with light oil anyway. Re-installed. Immediately no better. 
 

The ”wick” comment has my attention. I’ll go look for it and try that. 

[soth122003]

I've had problems with bouncing speedo's before as well. If the bounce was light (5-10 mph) it was usually the wick that was dry. Heavy bounce (10 to 30 or 40 mph) it was the cable binding. I used white lithium for the cable. Clean the cable with a lint free rag and the sleeve with a degreasing agent then lightly lube the cable with lithium and slide it back into the sleeve. The wick on the other hand uses a light weight oil like 10 and it can be a bite to get to without making a mess. The Plymouth service manual states every 10,000 miles or once a year for the speedo cable and wick should be lubed.

 

Joe Lee

[JBNeal]

additional information - speedometer cable lubrication

[busycoupe]

I used a ZoomSpout oiler to put oil into the little tube on the back of the speedometer.  That was 10 yeard ago, the needle is bouncing again slightly.  Time to crawl ubder the dash again.

[Tom Skinner]

Oil The Wick in the Back of The Instrument Panel. Fixed.

[keithb7]

My 1938….I don’t see a wick. Is  someome able to steer me towards a wick?

 

Edited October 24, 2022 by keithb7

[Los_Control]

Well, I would think if you had one .... would be on the very top most point & most difficult to get too.

 

 

Here is a shot of a spare speedo I have .... I think it is the original for a 1949 B1C truck. ..... Just saying it would be on the very top where difficult to see.

The light bulb location would be different between a 38 car & 49 truck .... But you should be able to reach up there & feel it?

 

Possible they did not have it in 1938, but will give you a idea what to look for.

 

[keithb7]

Thanks for the info. I went back in to take another look. Nothing up top either. I’m not seeing anything. 

[soth122003]

Hey Keith,

Just checked my motors manual 35-53 models. All it said about lubing the speedo was lubing the cable and the wick on top of the speedo cable input. Now yours may not have one, but I would check on the top where the cable screws in and on the top part of the extruded housing on back of the speedo. Mine is on top of the speedo cable input about halfway between the cable and the end of the connection housing and usually you can feel it. The wick housing is sometimes just a tube inset into the speedo and might have fallen out. Yours might not have one, but you might want to use a mirror to check for sure.

 

Joe Lee

Edited October 24, 2022 by soth122003

[DJK]

I used Marvel Mystery Oil to lube my wick, works great. Also used Sylglide on the cable, no bounce.

[Pete]

My '39 Plymouth does not have an oiling wick on the speedometer. I just lube the cable with graphite.

 

Pete

 

[LeRoy]

22 hours ago, Pete said:

My '39 Plymouth does not have an oiling wick on the speedometer. I just lube the cable with graphite.

 

Pete

 

I put several drops of oil on my wick yesterday and it smoothed things out a fair amount but there's still some bounce. I'll pull the cable out today, clean the casing well with brake clean and lube with graphite.

[DJK]

I actually removed the wick, filled the cavity with MMO, then reinstalled the wick.

[LeRoy]

I spent some time on my speedo and finally have significant improvement. 

I cleaned the cable and sheath with brake cleaner yet again. Relubed with the liquid graphite and used a zoom oiler on the little tube on the back (there's no wick in mine, just an empty tube).

That didn't make any difference so I took it apart again. In the process of taking it apart I brushed my finger across the back of the speedometer and realized the part that sticks out actually spins with the cable. I spun it back and forth and found it was pretty stiff. I soaked a rag with brake cleaner and let it soak around that joint. After it freed up some I re-oiled with the zoom oiler and now the needle is steady. I assume whatever was used on the wick in the past had set up somewhat and made that joint sticky.

 

If the speedometer was out of the car it'd probably be a much easier clean up task.

 

Thanks for the suggestions.

Andy

[soth122003]

Here your go Jim.