Video: is my tach broken?

[Guest]

http://www.youtube.com/watch?v=aWRVMpPkX0c

Oh, man. Why me?

I repaired my tach cable a few times by crimping it but the last time I did it the tach is moving around, jump a lot, and at the wrong RPM all the time. So I bought a new cable and the new one does the same. Is my tach dead?

[81ZUKI75]

Tach Problems

Here's what I found when my 750E tach went wonky...

The cable turns a magnet inside the gauge body. The magnet field creates an eddy current that turns a "cup" which is attached to a calibtrated coil spring that is attached to the needle of the gauge.




My "E" model gauges are easy to get into, and what I found was 30 year old gunk between the magnet and the cup. Not your ordinary gunk, just a stcky film.... just enough to create a drag on the cup. Cleaned it up and now it works smooth.

Your's won't be as easy to get at...go here for one method for opening yours. I need to this on my "T" model which is starting to act up too.

http://www.thegsresources.com/garage/gs_inside_gauges.htm

[littleroot]

re: link to cutting my tach

Whoa! Thanks for that link. He did a great job.

I had no idea there is no other way. I do not have the cutting tool though, but I'd be willing to buy one.

Anyone want to recommend the tools I need to buy for this and how much they would cost?

Thanks,
-Bob

[tkent02]

re: link to cutting my tach

Whoa! Thanks for that link. He did a great job.

I had no idea there is no other way. I do not have the cutting tool though, but I'd be willing to buy one.

Anyone want to recommend the tools I need to buy for this and how much they would cost?

Thanks,
-Bob

There's another way in. Take a small screwdriver, stick it in between the lower edge of the metal rim and the orange plastic, twist it. Work your way around the speedo, gradually all the way around until you can get it all bent far enough to open. To reseal it, bend the edge back over. It will look like crap, bit it's hidden out of sight when it's installed in the cluster.

[littleroot]

I hooked up my tach cable to a tach off a gs1000 (I think) and it turned correctly so I guess the cable is OK. Now looking for the right tools to cut the real one open

[Flaming Chainsaws]

I have a spare speedometer that I used for a little bit. While riding, the speedometer needle was bouncing around much like your tachometer but not that much. I cut it open with a hacksaw. But before cutting, I made a line with a pen then took a knife to make a guide for the hacksaw. Takes less than 10 minutes although having a drill press makes things easier. I found lots of debris in there that stuck on the magnet. Cleaned it all off and reinstalled. The needle moves smoothly now.

[posplayr]

[littleroot]

Thanks everyone. I've seen people opening them up using two methods but I have not seen is the inside of the tach. All the examples I've seen show only the inside of the speedo.

[81ZUKI75]

Speedometers and Tachs..

work off the same eddy-current principal. The only difference inside (on mine anyway) is the speedo has a gear to drive the odometer/tripmeter.

Awful picture but I think you can make out the magnet and cup...

[littleroot]

work off the same eddy-current principal. The only difference inside (on mine anyway) is the speedo has a gear to drive the odometer/tripmeter.

Awful picture but I think you can make out the magnet and cup...

Oh that is brilliant. I am now confident enough to cut her open!