1975 Ford 2000 Tach Drive Question

When I got this tractor, the tach didn't work (I've read here that they were prone to early failure); there was no cable attached. I removed the tach drive off the back of the generator, and found that the plastic drive gear had worn smooth in one spot. Ordered a new gear and a tach cable, along with a new instrument cluster since the original was completely bombed-out.

Installed all the bits while rewiring the tractor. Tachometer is not working. There are two possible reasons that I can see, and I'm not sure which of the two (if either) are supposed to be the way they are.

The first concerns the cable itself. Where it screws into the tach drive, there is a funnel-shaped guide that the screw-down seats on. When I screw it down a tiny bit past hand-tight, the funnel-shaped piece is still loose enough that it will tilt about 20 degrees in any direction. Is it supposed to seat tightly, or is that amount of play built in to the system? As a side note, the gauge end of the tach cable does seat tightly so the the funnel-shaped guide on the upper end is tight so that it can't move.

The second question concerns the tach drive assembly itself. When I removed the original worn out gear, I couldn't see any type of packing around it, so I just wiped out all the old hardened greasy dirt, soaked it in some TSP, and scrubbed it down with an old toothbrush. Once it was clean, I put the new gear in, and noticed that there was some play between the gear and the cylindrical housing it sits in. I couldn't see any wear-- the housing looks like it is still perfectly round. I put a small amount of grease on the screw-down access plate where the plastic end of the gear sits, since it was the only spot I could tell that made regular contact with the gear. Screwed it back on the generator. Reattached the tach cable. Started the tractor. Tachometer jumped once to about 200 rpm, then nothing.

Took the tach cable back off. When the tractor is running, the bit in the housing that holds the square end of the tach cable just sits there not spinning, unless you touch it, in which case it spins under your fingertip.

All I can figure is that there was supposed to be some type of packing in the housing that held the gear against the worm drive (that comes out of the generator). Since I don't have any packing (or whatever it was, originally) like that in mine, it only makes contact when you push it.

Any commentary on this whole situation?

I'll be happy to supply pics if what I'm talking about isn't clear.

Thanks

Sorry if I misread but... Assuming you have a generator driven tach........


The worm gear on the back of the generator can be worn out.

I should've noted that the worm gear looks like it's in good shape. Thought about it while I was typing, and immediately forgot it. Shiny with no wear that I can see. The worm screw on it looks to be in perfect condition.

When the tach drive housing is pulled off, you can see the worm gear turns whenever the tractor is running.

The tach on my 5000 quit working so I took the little 90* drive adapter off of the back of the genny. The teeth on the driven gear looked worn so I bought a new gear. Tach worked fine for a while then quit. I bought a complete new 90* drive adapter and put it on. Tach works fine again. Maybe you ought to replace the whole drive adapter- I know they're not cheap- about $40 IIRC but if it makes the tach work it's worth it.

if the worm gear teeth are as tall as the shaft, then it sounds like the housing is worn out. I have seen bad drive gears, bad worm gears, but not a bad housing,, but it doesnt mean that you dont have a bad housing.. with them being full of dirt and grime, anything can happen.

good luck.. Bill

I already had the webpage up to order a new one, thinking that was most likely the answer... Just wanted to hear it from the pros before I dropped the dime.

Thanks !!