broken tach drive sleeve removal

[eil]

Hi guys. Got an interesting one here. The tach drive was leaking oil on my '80 GS850GL, so I set about trying to replace the oil seal. Long story short, the tach drive sleeve put up a hell of a fight and then broke:



I suspect that it might be RTV'd in there. Reasoning that the only way to get it out now would be from the inside, I opened up the valve cover (yet again) and removed the exhaust camshaft. But now that I'm in there, I really don't see how to get it out:



As you can see, I did some tapping, prying and vice-gripping, and all that's managed to do is wreck the soft aluminum of the sleeve somewhat. There's only about 1-2mm of clearance between the gear and the sleeve. Would prefer to avoid messing up the gear if at all possible. I have a new (to me) sleeve that I bought on eBay, but not a new gear. Over in my project thread, Dogma suggested a C-clamp, but that would only work if I could get the gear out of there. (And I'm not totally sure there would be the frame clearance for it in any case.)

Any suggestions on where to go from here? Tools, methods, etc?


If I can get this solved, this old girl might be hitting the road this weekend. But then again, I said the same thing last week...

[WShie]

If you can get a chisel or some kind of wedge between the gear and the sleeve you may get it to move. Had the same thing happen to me. Once it starts to move you can drive it out with a drift. As far as the gear goes maybe 50/50 mine didn't make it.

[tom203]

The baby vice grip (4 inch long) might be able to grab on to a gear tooth and let you pry it free- try grabbing on the lower portion of the gear, where there's no sign of contact with cam gear.

[Agemax]

apply some heat and tap the gear, it may have some sort of sealant in there but there is also an o ring. it could all be dry and a bit corroded.
with some heat it will tap out but it may take a hefty tap to get it moving, it wont damage the head

[recycled64]

I'm a little concerned that the gear and the holder appear to no longer be 'in line' with each other in your excellent picture, the heat idea expressed here is good, and I would consider using a can of 'compressed air' (usually for use in cleaning, blowing dust out of electronics), which gets colder and colder the more you expel it. I would hope that you could 'shrink' the holder that way, and after that use only a very localized pencil flame on the surrounding head material. Fairly harmless, and the less force used, the better. Also, you'll want to try to smooth over the 'nicks' we can see in the holder, remembering that too much pounding could expand (or 'mushroom')the aluminum in that area, pretty counterproductive. Best of luck!

[rustybronco]

I'm going with a combination of heating up the adaptor, or the area around it, with a propane torch then grabbing the exposed shaft on the outside of the head with a pair of 'vice-grips' and whacking them with a hammer - while pulling on the 'grips' inline with the gear's direction trying not to break the exposed portion off.

You can always fit a plug into the adaptors hole until you find a new gear.

[eil]

You guys are awesome. Thanks so much for the suggestions.

The chisel is a no-go, unfortunately. The sleeve is just about the softest aluminum ever made by human hands and it's stuck in there really good.

I already tried tapping and vice-gripping from the inside, but there's just nowhere to gain purchase.

The sleeve and gear are lined up, it's just a bit of optical illusion in the picture. (The engine is tilted forward, but the tach drive is roughly level with the ground.) Although, applying heat definitely sounds like a good way to go.

I'm going with a combination of heating up the adaptor, or the area around it, with a propane torch then grabbing the exposed shaft on the outside of the head with a pair of 'vice-grips' and whacking them with a hammer - while pulling on the 'grips' inline with the gear's direction trying not to break the exposed portion off.

You can always fit a plug into the adaptors hole until you find a new gear.

This sounds like the most potentially productive option. I'm just 90% sure that this will gouge the gear shaft, which must be ungouged in order to not wreck the new oil seal that I bought. Oh well. Hence the temporarily plug like you mentioned.

More suggestions welcome but I'll give this a go, tonight or possibly tomorrow. (Have to procure a propane torch, which is something I've been meaning to have on hand anyway...)

[cowboyup3371]

I used a screwdriver from the inside to help push it out as I was pulling from the outside.

[eil]

I had a few more tries at this, but still no luck. I bought a propane torch. Tried heating the area and pulling the gear shaft with vice grips. No dice, it still doesn't budge. But this could partly be my own inexperience at work because I have no idea how much heat the aluminum head can take before damaging it. I tried levering the gear out with an old screwdriver but all I'm able to do is break off the tips of the gear teeth.

At this point, I would even be okay with breaking the drive gear to get it out but I can't see how to do that either without damaging the head. Pretty much at the limits of my own skills and experience here...

I'd like to ask for some in-person help on this. I don't think there are many regular posters within driving distance of me (Ypsi/Ann Arbor area), but if there are any lurkers who could lend a hand, feel free to get in touch. I can repay you in food, beer, gas money, or any combination of these.

I'll take the bike to a mechanic as a last resort, but since I don't have a truck, I have no good way of transporting it without relying on a friend or neighbor.

[SqDancerLynn1]

Try turning the engine to get the gear into a better position

[eil]

The exhaust camshaft is out, so I can already spin the gear with my fingers. I do appreciate the suggestion, though.

[rustybronco]

Repeat...

then grabbing the exposed shaft on the outside of the head with a pair of 'vice-grips' and whacking them with a hammer - while pulling on the 'grips' inline with the gear's direction trying not to break the exposed portion off.

And if that doesn't work heat up the cylinder head, grip the outer piece with a pair of vice grips and place punch on the vice grips and whack it with a hammer.

It's best if you have two people doing this. One to pull the grips in a straight line, the other to punch in a straight line.

The only other thing I can think of to do is get a SHARP cold chisel and see if you can get a good bite on two of the gears teeth trying to 'punch' it out from the inside. Or possibly grind/cut a groove in the teeth so the chisel can get a good bite.

[WShie]

Mine was broken off exactly the same way as yours. Tried vise grips, made a slide hammer, heated with an acetylene torch, none of these methods worked for me. What did work was a sharp blow with a drift got it moving and then it finally came out. Good luck.

[WShie]

After looking at your picture I think this would work: Use a dremel to cut a groove in your tach gear perpendicular to it's axis about in the center just deep enough to capture a screw driver. Then using a hammer and screwdriver or drift to push the assembly out through the head using the gear as a pusher on the soft aluminum plug.

[eil]

Thanks for the replies and suggestions, see my responses below. I guess I'll just have to noodle with it some more... The offer for a visit is still open, I'm perfectly willing to compensate someone for their time.

And if that doesn't work heat up the cylinder head, grip the outer piece with a pair of vice grips and place punch on the vice grips and whack it with a hammer.

It's best if you have two people doing this. One to pull the grips in a straight line, the other to punch in a straight line.

This is more or less what I was doing... the problem is that the vice grip kept sliding off the end of the shaft when struck. Maybe I just have crappy vice grips? I'm also 90% certain that if the vice grips _did_ hold, this method will probably result in breaking off the gear shaft flush the already-broken sleeve...

The only other thing I can think of to do is get a SHARP cold chisel and see if you can get a good bite on two of the gears teeth trying to 'punch' it out from the inside. Or possibly grind/cut a groove in the teeth so the chisel can get a good bite.

I'll give this some thought the next time I try.

Is it possible to get the gear out of the way by prying it up / down side to side so that the gear would break or maybe the shaft that the gear is pressed onto would break? Maybe using vice grips? In looking at the parts fiche, does it appear to anyone else that the sleeve does not have a ridge or any diameter difference? Additionally, do you think that the sleeve / gear assembly is merely pressed into the head until flush with outer head surface as shown in the first photo and does not come up against a ridge? My thought is, if the opening in the head is simply a machined hole just like a piston cylinder and is same diameter all the way through,could the assembly be driven from the front and into the valve area? Or at least to break it loose, knock it back a bit?

The issue is that the gear has a little nub on the back that goes into a hole in the head. If it didn't, I'd be happy to whack on the gear to just break it and get it out of there. But I want to be careful not to booger up that hole.

And with regard to heat, I am thinking the head will take a lot of it before any possible damage. Just thinking out loud

Agreed, but I've never been a motorcycle mechanic before this, so I don't know exactly how much localized heat it can realistically take. If I damage the head trying to get this out, it will become a parts bike. (Which I'm actually considering already, despite how much I've put into it up to this point.) If I knew all this was going to happen back when all I had was a leaky tach drive seal, I would have said eff it, let it leak.

Mine was broken off exactly the same way as yours. Tried vise grips, made a slide hammer, heated with an acetylene torch, none of these methods worked for me. What did work was a sharp blow with a drift got it moving and then it finally came out. Good luck.

Well, it's somewhat a relief to know I'm not the first this has happened to. Can you tell me, where did you place the drift? On the rear edge of the gear? I tried whacking on the sleeve itself for a bit, but all that does is mushroom the aluminum.

Interested to hear about your slide hammer setup, too. It just occurred to me that I could try to find a keyed drill chuck, secure that to the end of the gear shaft and rig up some kind of slide hammer to it. Probably stands as good a chance at breaking the shaft as getting the whole thing out, though.

Do you have a cut off wheel such as a Dremel? Object of the exercise is to get the gear off and maybe the shaft out of the bushing or plug as well. If that could be done, a socket of a larger ID than the plug could be placed on the outside of the head over the plug to act as a receiver. A "C" clamp could be used to then force the plug into the socket. Or, socket placed as described, fit a bolt through the socket, through the hole in center of plug, a washer and nut then attached on the valve side. Perhaps hold that nut with an open end wrench if space is limited. Turn bolt head (which has a washer or 2 under it to keep from interfering with the square opening in socket) as required. I am thinking the plug would be pulled into the receiver socket.

Yep, the C-clamp trick might work if I can get the gear out. I have a dremel, but I don't think there's enough clearance to get a cut-off disc anywhere near the shaft of the gear. I might be able to cut notches into the "fins" on either side of the gear to get a teeny-tiny hacksaw in there, but I'm very leery of doing that since it might change how oil flows within that part of the head.

After looking at your picture I think this would work: Use a dremel to cut a groove in your tach gear perpendicular to it's axis about in the center just deep enough to capture a screw driver. Then using a hammer and screwdriver or drift to push the assembly out through the head using the gear as a pusher on the soft aluminum plug.

Considered this, but my fear is that the gear will simply spin upon whacking it. Unless maybe I can wedge a piece of wood or something underneath it...

Again, I very much appreciate the suggestions. Hopefully I can find some time this week to try them out. This weekend I'm taking the MSF basic rider course (second time, already licensed) and it's like 12 hours long both days!