1953 NAA Jubilee erratic tachometer

[Whistlin10Speed]

This past weekend I rewired my ‘53 jubilee and corrected the 12v conversion that was done by the previous owner, it runs so much better now and feels like it runs a lot stronger.

I noticed upon the first test drive that the tachometer bounces all over the place and doesn’t really work anymore, what’s strange is I didn’t touch it, the only thing I can see that feeds it is a line directly off the hydraulic pump. Any recommendation on what it may be? It needs to be replaced at some point as it has water in the gauge and is hard to read, just wondering what could cause that being that I didn’t touch it.

 

[old]

This past weekend I rewired my ‘53 jubilee and corrected the 12v conversion that was done by the previous owner, it runs so much better now and feels like it runs a lot stronger.

I noticed upon the first test drive that the tachometer bounces all over the place and doesn’t really work anymore, what’s strange is I didn’t touch it, the only thing I can see that feeds it is a line directly off the hydraulic pump. Any recommendation on what it may be? It needs to be replaced at some point as it has water in the gauge and is hard to read, just wondering what could cause that being that I didn’t touch it.

What you call a line is a simple drive flex shaft that is likely have seen a better day and going bad

 

[Whistlin10Speed]

What you call a line is a simple drive flex shaft that is likely have seen a better day and going bad

Is it a relatively easy plug and play replacement?

 

[old]

Is it a relatively easy plug and play replacement?

Yes if you can find a new one. If you can it is a unscrew both ends and put the new one on

 

[Hemmjo]

Is it a relatively easy plug and play replacement?

You may need to replace the drive cable also. At least clean and lubricate it. There is a flexible shaft inside a hollow flexible tube. If it is dirt, not lubricated, or just worn out, it can case the tach needle to jump around.

 

[Whistlin10Speed]

You may need to replace the drive cable also. At least clean and lubricate it. There is a flexible shaft inside a hollow flexible tube. If it is dirt, not lubricated, or just worn out, it can case the tach needle to jump around.

I went ahead and ordered a new gauge and cable since they both look pretty rough. Thanks for the advice!

 

[Sean in PA]

Cheapest thing to replace is the cable. If that doesn't help then it may be the geared drive unit on the back of the pump or the proof meter (tach gauge) itself. You can disconnect the gauge end of the cable and start the engine and see if the cable inside is turning consistently with the engine running. You can also connect it at the tach end and disconnect it at the pump end and connect a drill to that end and spin the cable inside to see if the gauge itself is smooth or jumpy.

 

[Btzj02]

I went ahead and ordered a new gauge and cable since they both look pretty rough. Thanks for the advice!

Word of caution. Have a way to verify the actual RPM of the engine after you install the new proof meter to verify the proof meter is calibrated correctly. The internal parts of these "new" proof meters are the same for all tractors with only a difference in the bezel and the internal calibration. I had to return two meters before I finally received the correct one for my 8N.