Broken tachometer needle

I've read a couple of threads about repairing or replacing needles. I've already been advised that this is pretty tricky and that just replacing the tach or the whole cluster is a better idea. I may end up doing that, but I thought I'd explore the repair route first. That won't cost anything and, if it's trashed already, what's the difference?

I think that I could glue the needle back together with some epoxy, but will it operate properly? Since this is an entirely mechanical device that relies on a very delicate spring, won't the heavier weight of the repaired needle affect how it responds?

I also read that the needle could be replaced with one from a Ford Escort or similar. The same question about the weight of the needle would apply here. Also, I'm afraid to pull very hard on the round base of the needle. Can it be popped off without damaging the parts below?

Lastly, in it's current broken state, the needle aims just a little below the peg at "0." Is it is supposed to be "wound" one or more times before resting on the peg or does it start there from a completely slack position?

Thanks!

 

read: http://xjbikes.com/Forums/viewtopic/t=14948.html for how to take the cluster apart. Yours is slightly different but very similar.

read: http://xjbikes.com/Forums/viewtopic/t=15303.html for what you'll find once in there. Go ahead and clean/lube the instrument BEFORE trying to fix it.

I wouldn't use epoxy; use a solvent-type plastic cement (model airplane glue, the liquid kind.) Or even CA (superglue.) Epoxy heavy. You can lightly glue the needle and it should not affect the instrument.

Before you pull the nub of the needle off, mark the magnetic drum with an "indexing mark" corresponding to the position of the needle. Then you don't have to worry about the "preload" thing. That is, if you even need to pull it off. Better if you can manage to not.

Once you've read through both of the above articles, post up any additional questions, or feel free to PM me; I've got quite a bit of mechanical instrument experience (although not always by choice. Tachometers don't like me.)

 

Thanks, Fitz. I should probably also add that I experienced a loud whine in the tach, but I think that did not start happening until after the needle was broken. On the other hand, I guess some other failure of the instrument could have caused the needle to break???

I replaced the tach cable just before leaving on this trip.

 

Could be your cable being dry. They tend to hang and wind up then release spinning the needle wildly and end up breaking it off.

 

I suppose, although the cable was brand new - installed a couple of days before - and I lubed it liberally before I hooked it up.

Thanks.

 

if you want to just skip the whole procedure, i have a working tach from an extra 550 maxim gauge cluster if you're interested.

 

Here's what I do.
When your done you can't tell it was broke.
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You can fix it ... you just need to put your Precision Hat on.
Mask the face of the Speedo off with some Aluminum Foil followed by some Paper towel.
Get some 5-Minute Epoxy.
Epoxy a Tooth Pick to the underside of the fragment.
Just to the butt-end and hold it perfectly straight until the Epoxy cures and the Tooth Pick becomes part of the former indicator that broke-off.

Next.
Mix a SMALL amount of Epoxy and use another Tooth Pick to "Coat" the glued-on Toothpick.
Build-up a nice "Bead" of Epoxy from the break to the tip of the glued-on Tooth Pick.
Cover the repair with a coat that will built-up and form the new Speedo Needle.

While the repair bead is almost cured and still a little bit flexible ... nip-off the end with a pair of fingernail clippers to the correct length.
Leave it alone after using a Razor Blade to remove any Epoxy that starts to drip-off and fall on to the paper towel.
In other words ... clean-up and "Shape" the underside ... flat.

When it's done getting cured ... do a final shaping and "Roughing-up" of the surface with a brand new Emery Board. Your wife should have plenty.

Once you have finally shaped and lightly sanded the surface ... paint it.

Get the paint from the "Testors" (Trademark Brand) Paint Rack at a Hobby Shop.
The matching Red is: "Italian Red"
An alternative Needle indicator color is: Florescent Yellow.

While you are at the Hobby Shop; pick-up a tiny paint brush (Artist type) to use putting-on the paint over the repair job.

Don't try to get the repaired Needle painted all in one sitting.
Apply a first coat.
Let completely dry.
Emery board out any "Pulls or wrinkles"
Apply second coat.
The second coat might do the trick.

If it needs a third coat ... wait for the second coat to dry.

New Speedo Needle Indicator.
Cost: 10 Bucks or so!

Change the Bulb colors to anything that is available with pre-colored bulbs.
Red, Blue and Orange are nice.

Take your time and do a nice job.
Wipe the Bulb Holders with a Q-Tip soaked in Armoral.

PS: A two-tone Indicator with the tip painted DayGlo color and the needle body stock is trick.

Use some 3M Vinyl Masking tape to mash-off the Red Line area of the tach and add some Red color to the Tach.

 

There ya go! Probably the best solution. But be sure to clean and lube it before you install it so it doesn't just pack up on you in a few hundred miles.

That's the "scream of death" remember how I said tachometers hate me? I've had three of them do that now; two were "saved" by cleaning and lubing although one of those which now has 5000 more miles on it is beginning to holler again on chilly mornings. One of them fragged its input bearing/bushing and couldn't be fixed.

 

I was able to disassemble then clean and lube both the tach and speedometer. I went and bought some Super-Glue to fix the needle thinking that the instant bonding of that product would be an advantage. I was very surprised when it wouldn't bond at all. It did say that it doesn't work with polypropylene or polyethylene, but I didn't think the needle would have been made out of either of those.

My only option at that point was a two-part quick setting epoxy. I was already worried about the extra bulk so I didn't use Rick's toothpick method. I just gobbed a little on the end and help it in place for several minutes. Then I mixed up a little more and laid a coat over the whole thing. Finally, after it had set up a bit, I very carefully trimmed away some of the excess with an exacto knife. It isn't perfect. Sort of like a needle with some scar tissue. Then I painted both needles and put them back together.

Good news: the whine is gone!

OK news: the tach seems to be reasonably accurate at idle.

Bad news: the higher the rpms, the less accurate the tach is. This is what I suspected would happen by adding weight to the needle. The magnet spins inside there and pulls on this very delicate spring. The weight of the needle has got to be a critical element in that whole equation.

I'm going to try and find another tach (a couple of you have already offered) and just swap it out, then keep this one as a spare.