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Posted: Fri Jan 21, 2011 7:05 pm Post subject: Bouncing speedometer needle: Possible causes?
Got another tech question that's puzzling me: My old '79 TS185 is pretty much restored and looking/running good, with one exception: At certain speeds, usually around 40-50 or so the speedo needle tends to bounce around somewhat erratically. It doesn't swing from end to end, but moves back/forth in 5-10mph increments. I've cleaned & lubed the gears in the hub & use new cables, but remain puzzled.
The only other possibility I can think of is something in the speedo itself is off. If so, what does one look for and how are these old speedos disassembled? Looks like the chrome trim ring would have to be ever so gently pried off.
Joined: Dec 26, 2007 Posts: 1283 Location: Scottsdale, Arizona
Posted: Mon Jan 24, 2011 5:01 pm Post subject:
There's not much you can do about it. The needle movement was damped by a coiled tension spring. Those springs lose tension over time and allow the needle to float around. A rough road probably makes it bounce around a lot. You might try an instrument shop for repair or find a new instrument. My GT500 tach did the same thing, so I know what a pain it is.
You can repair most of them if you have enough patience and a steady hand.
Usually have to pry the case or bezel off to get to the insides.
The old lube inside hardens after several years and makes them erratic.
Once inside, use two teaspoons to remove the needle, and be careful not to get any solvent on the faceplate.
Soak the works in solvent and re-lube, and you should be ok.....unless there is major rust.
Does your speedo look like this?
http://cgi.ebay.com/ebaymotors/SUZUKI-TS185-TS-SPEEDO-SPEEDOMETER-NOS-/160519042397?pt=Motorcycles_Parts_Accessories&hash=item255fae355d
Posted: Wed Jan 26, 2011 6:38 am Post subject: My speedo looks like this picture-plus a question
brewsky wrote:
You can repair most of them if you have enough patience and a steady hand.
Usually have to pry the case or bezel off to get to the insides.
The old lube inside hardens after several years and makes them erratic.
Once inside, use two teaspoons to remove the needle, and be careful not to get any solvent on the faceplate.
Soak the works in solvent and re-lube, and you should be ok.....unless there is major rust.
Does your speedo look like this?
http://cgi.ebay.com/ebaymotors/SUZUKI-TS185-TS-SPEEDO-SPEEDOMETER-NOS-/160519042397?pt=Motorcycles_Parts_Accessories&hash=item255fae355d
Although I don't have a tachometer, the speedo shown here on the left appears to be the same:
Posted: Wed Jan 26, 2011 7:48 am Post subject: Re: My speedo looks like this picture-plus a question
jws3 wrote:
brewsky wrote:
You can repair most of them if you have enough patience and a steady hand.
Usually have to pry the case or bezel off to get to the insides.
The old lube inside hardens after several years and makes them erratic.
Once inside, use two teaspoons to remove the needle, and be careful not to get any solvent on the faceplate.
Soak the works in solvent and re-lube, and you should be ok.....unless there is major rust.
Does your speedo look like this?
http://cgi.ebay.com/ebaymotors/SUZUKI-TS185-TS-SPEEDO-SPEEDOMETER-NOS-/160519042397?pt=Motorcycles_Parts_Accessories&hash=item255fae355d
Although I don't have a tachometer, the speedo shown here on the left appears to be the same:
I am not sure I follow you. Two teaspoons? Does the needle have to come off? Also, what kind of solvent & and what kind of lube does one use?
Too bad there isn't a DIY article. Have yet to see one.
Thanks.
There are some threads on the honda305 forum with pics etc. I will look them up and post some links.
The 2 spoon trick allows you to remove the needle without bending it, as they are pressed on and hard to get a hold of without bending.
Just place something thin on the face to protect it and position the spoons 180 degrees as close to the shaft as you can, and pry up with both at the same time, allowing the needle to pop off.
You can lever the bottom of the spoons on the screws that hold the faceplate on.
If you remove the needle and plate, you can submerge the assembly in solvent without damaging the paint and coating on the plate.
If there are any plastic gears, it might not be good to submerge them in solvent, just use spray carb or brake cleaner or the like.
You can use mineral spirits, gas, carb cleaner or whatever to clean the old gunk out.
Use grease on the gears and light oil on the pivot bearing surfaces.
You can spin the works with a drill (usually in reverse) to check the operation for smoothness.
There will probably be a tiny phillips screw in the end of the tripmeter knob that secures it to the shaft.
First , to get it apart, remove the knob, and separate the plastic housing from the metal base by prying something under the plastic edge, working all around the circle, a little at a time.
Don't worry if some of the plastic edge breaks off, you can seal it with RTV, and the joint is probably hidden in the mount anyway.
Here's a Flicker link to some photos of a Honda rebuild:
http://www.flickr.com/photos/63154743@N00/4162196953/in/set-72157622068179860/
Several threads on this site: Type in "speedo repair" and click on "all terms"
http://www.honda305.com/forums/search.php?mode=results
They are all similar on the inside, as far as I've found so far.
The speedo cable drives one part of a "bellhousing shaped flywheel", and the needle shaft is connected to the other part.
One of them has a magnet, and the speed of the magnet spinning past the other drives the needle shaft, against the resistance of the spiral spring.They are not physically connected.
You can actually calibrate the correct speed reading by adjusting the tension of the spiral spring.
The speedos with plastic housings are easier to work with than the ones shown, as you don't have to bend any metal bezel to get it apart.
Posted: Wed Jan 26, 2011 11:24 am Post subject: Very helpful--got a follow up
brewsky wrote:
Here's a Flicker link to some photos of a Honda rebuild:
http://www.flickr.com/photos/63154743@N00/4162196953/in/set-72157622068179860/
Several threads on this site: Type in "speedo repair" and click on "all terms"
http://www.honda305.com/forums/search.php?mode=results
They are all similar on the inside, as far as I've found so far.
The speedo cable drives one part of a "bellhousing shaped flywheel", and the needle shaft is connected to the other part.
One of them has a magnet, and the speed of the magnet spinning past the other drives the needle shaft, against the resistance of the spiral spring.They are not physically connected.
You can actually calibrate the correct speed reading by adjusting the tension of the spiral spring.
The speedos with plastic housings are easier to work with than the ones shown, as you don't have to bend any metal bezel to get it apart.
Thanks for taking the time. The Flicker link does show what from the outside looks similar. Unfortunately, the Honda305 link came up blank. What search parameters did you use so I can recreate it?
I have a metal encased speedo. I see some members have apparently used a service in CA to repair or rebuild theirs. I wonder if that is a better path, since even if I do get it apart and discover something I have no parts to repair, nor are internal parts even shown on the parts diagram. About the most I could do is try to carefully clean it and lube it.
Joined: Jan 05, 2011 Posts: 145 Location: Heanor, UK
Posted: Wed Feb 02, 2011 12:55 am Post subject:
There is a spring that pulls the needle back to zero but there is also liquid silicon which slows the needle down, you normally see it when the speedo has been upside down for a time, you get a stain on the face where the silicon has leaked out, your problem could be a slight offset by the magnet cups. _________________ Life begins at 40, head on the tank for 45.
http://www.youtube.com/watch?v=x5XShCZ6Jsg
Posted: Wed Feb 02, 2011 6:00 pm Post subject: No stain, but the magnets are a possibility. (more)
skungheeney wrote:
There is a spring that pulls the needle back to zero but there is also liquid silicon which slows the needle down, you normally see it when the speedo has been upside down for a time, you get a stain on the face where the silicon has leaked out, your problem could be a slight offset by the magnet cups.
I suppose the only way to know for sure is to take the speedo apart as some have described or, perhaps better still, send it to a repair/restoration place!
Posted: Wed Feb 02, 2011 8:07 pm Post subject: Ouch. Don't want that.
JG122 wrote:
just wanted to add, that if you do nothing, the bouncing will eventually cause the needle to break...
you'll still have the hub in the middle to estimate speed though
I've heard around that there is a place in San Diego called "Foreign Speedo" that can restore it. Ordinarily, I'd like to try it myself, but seeing as how replacements are hard to find a few bucks may be worth it. I'll be calling them shortly.
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