Triumphrat

Mrsinister

I was riding today (79, 750 Bonne) and my tac stopped working, it seems that the ring on the back fell off? My manual shows a ring that goes over the rear of the tac gear box. When I slide the gear that hooks up to the tac cable it slides back down and doesnt work. If I slide it up into the box and hold my finger pushing the gear up into the chamber and start it, the tac works, but stops as soon as i remove my finger. Do I just need to get the cap that goes over the back or is it supposed to be open on the rear side of the gear box?

Side question if it is supposed to have a cover on the back there is very little room to get in there Do I have to take of the tac box?

Sinister

Sunshine Jim

"a ring that goes over the rear of the tac gear box"

? theres a ring there? is your tach driven by a cable or electric?

if it's a cable drive off the engine theres a "ring" on the tach cable end to fasten the cable to the tach that rattles loose and slides down the cable. if so it slid down into that mess of cables and wire, just trace down the cable and you should find it. it might have slid down all the way to the motor tach drive and look like it's part of that assembly. make sure the square end of the interior cable is fully seated in the tach before you tighten that 'ring' often referred to a "ferrule" (ferrill is how you often hear it)

Mrsinister

The tach is driven by a cable.
If I understand correctly There should be like a o ring that is attached to the cable itself and you take that and tighten it to the tach gear that the tach cable its self slides on to?

Also If i miss understood you, the gear that the tach cable slides onto should be free flowing> and if its not connected it should slide right out of the gear box to where the end is exposed and hitting the engine case? Theres no plate or screw covering from the oppisite side of the cable that stops the gear from sliding out.

Snakeoil

Okay, I know it's not just me.

Mr. Sinister (or Mrs. Inister) either grew up with us in the 60's and 70's and had a much worse drug problem than we had, is much younger than us and has a bad drug problem now, or immigrated here with Latka Gravas but does had yet to develop Latka's command of the English language.

Mr. or Mrs.,
A mechanically driven tach is fastened to both the tachometer and the tachometer drive on the engine through a mechanically driven cable that is contained in a vinyl covered flexible metal sheath. Each end of the sheath has a swaged flanged fitting that butts up to the cable connection on both the tachometer and the tachometer drive. On the tachometer end there is a knurled nut that I believe you are calling a "ring" or "o ring". It screws to the back of the tachometer and holds the cable and its sheath in place. A similar knurled nut is also what holds the other end to the tachometer drive gear on the front left side of the engine case. In that end of the sheath there should be a small drive shaft about an inch or so long that looks like a screwdriver on one end. Screw both of the the knurled rings onto the tachometer gear drive and tachometer and take the bike for a ride.

If this fixes your problem with the bike, we will all be very happy. If you are still in high school and work very hard to get an "A" in English this year, we will all be even happier.
regards,
Rob

Mrsinister

Well I've been going on what I think things are called. So i guess that makes me an idiot in robs eyes.
I dug out the manual which I should of done in the first place, and the schematic of the tach gear box tells me this about my problem.
I am missing a bushing between the driven gear and the spade that connects to the Tach cable end. If I get the bushing it should hold the driven gear in place and stop it from coming out the opposite end?
Or am I still missing a piece?
Because on the box itself there are 4 indents on the backside of the gearbox where it looks like something slide Behind the driven gear, it looks like a emd cap not to different like the one you thread on to the Driving gear side just minus the threads.

If this still sounds like crap jumble I'll just ask some other people who arent going to be rude.

oh and im on a lot of drugs having a way better time than you.

Caulky

I`m not sure what your problem is.
But assuming the tacho assy is similar to earlier models.
Have you lost the threaded cap from the driving gear, or is it the driven gear?
If it is the driven gear, which is most likely, there is a spacer (disc) which pushes the pinion up to mesh with driving gear.
This assembly is held together by a Welch washer.
This Welch washer needs to be given sharp tap with a hammer to fit it. It is convex in shape, but when hammered in it makes an interference fit into the body.

Snakeoil

Mrsinister,

Sorry I ruffled your feathers. I was simply busting your chops. Go back and read your first emails and see if they make any sense to you. In my short time here I feel confident in saying that anyone on this forum is more than willing to help you with your problem. But if we have a hard time decyphering what you are trying to tell or ask us, you won't get a lot of valuable help.

To show you that I mean what I say, attached is the exploded view of the tach drive assembly. I think Caulky has identified your problem. Referencing the attached diagram, which is for a '76, I believe it is the welch washer that you probably lost along with the thrust cap. These are parts 18 and 19 on the diagram. This would explain your ability to push up on the driven gear Part 17 to re-engage the spade, part 22 that drives the tach cable.

If those parts are all there, then you lost the drive side of the tach drive which would be parts 15 (end cup) and it's mating o-ring part 16. An o-ring by the way is a rubber (generic term because material varies with application) sealing ring with a round cross-section. The end cup threads into the end of the tach gearbox housing Part 8 (OEM mistake) on the diagram and part 10 on the parts list.

Last piece of advice I have is learn to laugh at yourself. If you get pissed off at every person that busts your chops, you're going to be wasting a lot of time better spent having a good laugh.
regard,
Rob

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pookybear

Hello mrsinister,

Sometimes thing look good when written and end up reading not
so well. I am sure Rob did not mean to get you upset. In his
defence I did have to read your post three times to get to the
problem. That is alright, it is just a thing about the right words
to use.

As for the problem the welch plug fell off of your tachometer gear
box down on the engine. This is a small plug like a freeze plug
in a car engine. However, the welch plug has no sides and is just
a cupped disc. The disc is installed with the cup side out and then
give a slight tap to expand the disc in the hole. It help if a little
sealer is used as well. And yes there is another part missing in
the tachometer drive as well it is a small spacer that keep the
driven gear in mesh with the driving gear. This is what the welch
plug keeps in place. As for the size of the welch plug, I have
forgotten been to long, but I ordered it from Napa. I just made
up the spacer needed and greased up the assy.

It would help you to remove the tachometer drive from the engine
case to do this job. Just take the large retaining screw off the
end of the tachometer drive, remove the driving gear and then
you can get to the retaining nut that holds the drive box to the
engine case. CAUTION, this nut is a reverse thread, it is a
clockwise turn to loosen!!!! When you get the case off you
can take it to Napa to size up the proper welch plug and it will
be easy to install it as well.

I hope this helps you out. And everyone please remember we
all started wrenching at one point and we did not have all the
answers when we started.

Pookybear

Sunshine Jim

I'm on drugs too but none of mine are fun anymore.

sigh...

what we need, it looks like is a thread with some good illustrations. I tried the manual but the illustration is the tach head and cable, no detail eh?

so is there a good instrument exploded view somewhere on the net?

anyone got one they could post?

hang in there sinister we're trying to help,

Rob is probably a casualty of all the "I've got this whatchamacallit that fit's into my thingamabob and it won't spin right, what's wrong with it?" requests.

Sunshine Jim

"Ask and ye shall receive"

eya Snakeoil, that's a beauty illustration, what's it out of?