Speedo

[simpzimmer]

My speedometer isn't very stable. It jumps up and down and doesn't really give an accurate reading always. Any advice? Also, I just bought one on e-bay for $30. I understand that they're not made any longer. Did I get a good deal?

 

[Alan_Myers]

Hi,

Most likely cause of the speedo jumping around is that the cable is dry and needs lubrication.

To lube it, remove hang it up, tape a small plastic bag around the end to act like a funnel and put some oil in it, working from the gearbox end of the cable.

Use pretty heavy weight oil and try to estimate when enough has gone in to lube approx. the bottom half to two thirds. Reverse the hanging so that the gearbox end is down, and let extra oil drip out for a couple days. The reasoning here is that the spinning cable will tend to pull the oil up toward the speedo, and you don't want oil getting inside the speedo or in the cockpit.

An alternative to the plastic bag trick is an oversize syringe-like tool that's used to lubricate motorcycle and bicycle cables. These are available at some motorcycle shops. They come with rubber plugs for one end, that are sized to seal around different size cable sheaths. This tool is faster and gives more control over how much oil is injected into the cable, than does the plastic bag trick.

I'd try cable lubing before messing around with the speedo or having it rebuilt. Probably 8 or 9 out of 10 times, it's the cable and not the speedo.

/ubbthreads/images/graemlins/cheers.gif

 

[Geo Hahn]

I got my new inner cable from a local shop who specializes in repairing speedos for old cars. His advice was to use grease, just take a handful and draw the cable thru, then insert into the housing. I had always heard to use graphite (for the reason Alan cited of oil migrating into the speedo head) but I am now using the greasy kids stuff and everything seems fine.

BTW, $30 for a working speedo sounds fair. Do not throw the old one away as there are quite a few parts in there which you may someday need to repair another unit. Also, the old one would be good practice to learn how to tear down, clean and reassemble one.

 

[Andrew Mace]

I've been told by at least one world-renowned Triumph expert (John Kipping) that a long-dormant used or even NOS speedometer might well need cleaning and relubrication before it's truly "fit" for service. Not an absolute given, but a strong possibility.

As for greasing the cable, be very sparing in use of the grease, lest ye receive a nasty note about too much grease found inside your speedo/tach, said note in the box Nisonger uses to ship your rebuilt instrument back to you! /ubbthreads/images/graemlins/blush.gif

 

[dklawson]

As Andrew said, if the gauge has not been used for a long period, the lube inside the gauge can dry up and/or the odometer pinion gears can seize to the diecast housing. It's a good idea to have it cleaned by a local speedo shop before putting it into service.

On my LBCs I've found that if the cable is dry, you may need to inspect the cable's outer jacket for cracks and tears that let in water. If it's damaged (and you don't want to replace it) you can sometimes get by with things as simple as wrapping a protective layer of electrical tape over the degreased damaged area.

I use a modest amount of gear oil on the cables. I don't use grease because it tends to get too stiff in cold weather. As mentioned, don't overfill the cable with any lube as it can work its way up into the back of the instrument.