Wacky Tach!

[Jeff396]

I have a '66 Triumph motorcycle where Lucas, The Prince of Darkness, still reigns supreme. What's the joke, spit on the ground and it will still stop running due to moisture!/w3tcompact/icons/smile.gif My brother used to own a motercycle shop where he made a pretty good living totally rewiring British motorcycles.

Jeff

 

[billboe]

Hayden,

That makes sense to me...

/w3tcompact/icons/frown.gifOUCH! I just called the dealer... $83.04 for the sending unit!


Billboe

 

[billboe]

<font color=blue>And I'm disappointed that you didn't entitle this thread "Wacky tachy".</font color=blue>

I guess I missed that one... I also recently had to replace the air vent cock because the knob fell off. You can imagine the subject titles that I could have used there! /w3tcompact/icons/wink.gif

Billboe

 

[billboe]

Yeah Bob, I was wondering that also!?!? When I removed the sending unit, the bolts weren't totally tight, so, that could have been the culprit. However, the bolts weren't that loose!?!? It seemed that the "key" just didn't insert far enough... I just hope a new sending unit will not have the same problem...

Billboe

 

[billboe]

The sending unit I have mentioned before is referred to the "CASE,H/METER DRIVE" (part #: 38240-34660) in the parts manual. I know this cable is attached to the tach because the tach moves when I turn the cable by hand. I just think it is interesting that it seems to also drive the hour meter... I assume the hour meter operates at a constant speed when the cable is turning (no matter the engine RPMs) and that it doesn't turn faster when the engine is turning faster...

I would have assumed that the hour meter was an electrical clock and not driven mechanically...


Billboe

 

[hayden]

Nope, the hour meter actually counts engine rotations. It's calibrated to count hours at your 540 PTO RPM engine speed. Interesting way of measuring time, isn't it. But when you really think about it, engine wear is really a function of the number of times the thing goes around so it makes sense that there is less cumulative wear over the course of 1 hour at 1000 RPM as compared to 1 hour at 2600 RPM.

Either way, it seems there are lots of "hour" meters that work this way.

 

[Bob_Trevithick]

Just as an amusing aside here, when my first little tractor, a GT235, was delivered, it had no hour meter.. so I had the dealer install one. A few days later, after returning from a vacation, I was surprised to find that my tractor now had 216 or so hours on it. Seems the mechanic hooked it to a wire that was always hot. oopsey! /w3tcompact/icons/smile.gif

Bob Trevithick

 

[Bird]

<font color=blue>I would have assumed that the hour meter was an electrical clock and not driven mechanically</font color=blue>

Just depends on which tractor you buy./w3tcompact/icons/wink.gif My '95 B7100 was an electric clock, and while it was wired right; not like Bob's, on a wire that was always hot/w3tcompact/icons/laugh.gif, it sure would keep running if you left the key on, even with the engine off. But my B2710 is like Hayden described (and what your tractor has).

 

[billboe]

Ok... I'll give this thread a bit more life...

I ended up replacing the sending unit (carver's saved me a few buck and a drive to the dealer) and my tach still doesn't work properly /w3tcompact/icons/frown.gif! I did another close inspection of the cable and found no problems/w3tcompact/icons/crazy.gif. I removed the new sending uint to make sure it wasn't having the same problems as the old one (it wasn't, it was still looking good!)/w3tcompact/icons/crazy.gif... The only thing left is the tach itself!?!? Any thoughts!?!?


Thanks!

 

[Kubota3710]

Did you ever find the fix?

Mine on an L3710 just went wacky also. Turn key off and it settles above 3000 rpm. Start the tractor and it vibrates in the high 3000s. It has 750 hours and I recently got it so I don't know if the cable has ever been lubed.

Anyone else had this one or know what likely cause?

Thanks, Rich