Fixing a slow tachometer

[bmlbytes]

I had a tachometer that would very slowly go up to the RPMs and then go very slowly back down. The tach is pretty much useless like this, but a new tach will cost around $130. The tachometer and the speedometer are pretty much impossible to get into to try to repair. I found a guide on this site somewhere that said to dremmel it open then epoxy it closed when you are finished.

Here is what I did to fix the tachometer. I used a Dremmel to cut the plastic right under the glass. I suppose using a fine toothed hacksaw would also work in this situation. After that I took the two screws holding the unit to the case off. Now I had access to the mechanical parts of the tach. I sprayed it all with some Liquid Wrench Penetrating Oil. The tach started spinning freely after that. I used some WD-40 to clean everything, and to keep it well lubed. I put it all back together, then used some 7 minute epoxy to glue the window back on. With the plastic sleeve and the foam rubber thing that goes around it back on, you can not even tell that I worked on it. The tach works perfectly now.

Also, if anyone is going to do this, the oils do not hurt the gas gauge that was found on my GS550L. Oil does not conduct electricity or interfere with magnetics, and the gas gauge is an electrical system. WD-40 will actually clean electrical contacts.

I am very pleased with the results. You can not tell even a little that the gauge was cut and glued back together. The tach was bothering me, because I get obsessive about things working properly, even if they are kind of useless. Now I can rest assured that I have a working tach, that I will likely never use (I mean who looks down at the tach before shifting anyway).

 

[chuck hahn]

Could have just took the cable off the nipple and bent the spray hose on a can of your Favorite penetrating oil and squirted it up in there. Worked for me. Also take a piece of welding wire and use it like a gun cleaning kit to pull a small piece of rag thru the cable jacket to clean it out. Some say to lube the cable and reinsert, but i leave mine dry..oil and "lubes" tend to gather dirt and turn into the same sticky paste you had just removed.

 

[Buffalo Bill]

I learned somethin'?but need more accuracy

I learned somethin'?but need more accuracy

About slow tachometers, a mechanical tach is by nature behind the actual RPM during acceleration. Maybe by as much as 1000RPM during hard acceleration?
I sometimes would prefer a digital tach, so I my shift points will be accurate.
Do you know of a small one I could put on my 1100G?
Bill

 

[bmlbytes]

Could have just took the cable off the nipple and bent the spray hose on a can of your Favorite penetrating oil and squirted it up in there. Worked for me. Also take a piece of welding wire and use it like a gun cleaning kit to pull a small piece of rag thru the cable jacket to clean it out. Some say to lube the cable and reinsert, but i leave mine dry..oil and "lubes" tend to gather dirt and turn into the same sticky paste you had just removed.

Yes I tried that with no success. After opening it I could see why. The tach cable spins a magnent wich then spins another thing at a slower pace. That part turns the needle. That second part was the part that was gummed up.

 

[boingk]

Good trick, bmlbytes. I need to get some lube into my tachometer as its kinda erratic sometimes. I'm a big fan of lanolin lubricant, try it for yourself and you'll never use anything else. WD40 is still good as a penetrating lube though, and is a good degreaser to boot.

As for a digital tach, a quick eBay search turned this up:

http://cgi.ebay.com.au/M-SPEC-52MM-...=AU_Car_Parts_Accessories&hash=item1e5b53f89c

CHeers - boingk