engineer wrote on 11/07/12 at 13:12:22:

I wish I had all those things to work with that you have. I am out of the trade, and all I got at home is a vise and a few files. LOL
I would make my own new piece if I could. The piece cost about $8, and hopefully it'll last another 18k miles.

justin_o_guy2 wrote on 11/07/12 at 20:52:32:

That's what I was afraid of when it happened. Between that piece, the chain adjuster and the oil pump gear, you got a pretty nice clusterf.ck waiting for you in a small area.
Perhaps I find me a piece of quality tool steel and whip out my file and make my own part.

justin_o_guy2 wrote on 11/08/12 at 09:07:04:

I concur that there could be a little more meat on it and bigger radius, but not much as there is little room for improvement. The biggest improvement would be proper steel and heat treatment.
Concerning the making your own part, the biggest challenge on that part would be the oval shaped hole in the middle made an exact fit to the shaft. I noticed there was some slop to it, but not from wear. It was that loose when new. A little too much slop for my taste as this aided the fracture point with jamming the edged part of the shaft on the inside of the part right where it broke. Kind of like laying glass on an edge and breaking it off. The tolerances should be tighter than that, no doubt about it. There is no reason for that much slop, not even thermo expansion.

I understand that there might be people thinking what do I know compared to engineers at Suzuki, but I tell you that this part is definitely a shame for any engineer or whoever else decided to put it into mass production like that. The way it broke apart says it all.
If it had been manufactured like the gears in the transmission or some parts in the motor, it wouldn't break like that.
The design of the cam chain tensioner issue just as hideous.

I say it again: I am still convinced that the piece was not properly annealed. I used to make sheet metal stamping tools and during my education we we're shown examples of improper annealing after hardening the stamps and they just busted like that piece here.
Looking at it shows that it broke like a piece of porcelain. Putting the halves together, and they fit almost without a visible fracture line.
That tells it all.

Annealing steel is pretty much a matter of timing. Unlike with hardening you don't use oil to quench it. The oil provides a slower cooling that if you would use water it could crack or warp the piece you're working on. The red glowing piece is too hot to cool it too fast.
Also when you stick in the oil, don't hold it stationary, but move it around in the bucket to avoid heat pockets that surround the piece and would not provide sufficient cooling power. The part would not get hard and simply stay soft.
Annealing goes by color, meaning slow heat up with a flame and observing when the color of the steel changes. When the piece starts to get golden, get ready. Then follows purple and in the bucket it goes immediatly. When it turns blue, depending on the steel you are perhaps too late and the part already lost the integrity you want. This process keeps a layer of hardness on the outside, but maintains the toughness of the original steel structure it had before hardening.
This is pretty much the old school way.

Quenching in oil is not an annealing method, it is a hardening method, and it doesn't bring the temperature down slowly. In fact it's quite the opposite. Oil-quenching is used because it's the fastest method to bring the temperature down and this is what hardens metals.

Brass is different though. Simply heating it is enough to anneal it and it doesn't matter how you cool it - so dipping it in oil is fine. Don't try that with anything else because it will harden it. Annealing is typically done in an oven that can slowly bring the temperature back down, much slower than just leaving it in the ambient temperature of a room. A2 is an air-hardening steel that will harden all by itself in the air after heating it so to anneal it you MUST use an oven.

I still think there are too many teeth on that thing..

ralfyguy wrote on 11/13/12 at 08:33:06:

Any time you 2 want, I got scrap that you can play with.
You can modify the existing teeth or flip it over and make a whole set of new teeth.
the plunger is case hardened so you'll need a carbide tool to cut it or a grinder.

ralfyguy wrote on 11/13/12 at 10:06:34:

The only spare of those is in 2 pieces like yours.
I thought we were discussing the cam chain adjuster plunger.