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A Broken Valve Shim and It's Aftermath

  • Thread starter Thread starter jrobert94
  • Start date Start date
Before this thread started, I have only seen two cases of shattered shims.

One was my Kawasaki. The shim shattered when the tool slipped off the bucket while the shim was not fully seated.

The second was in another member's bike. He missed a shift, found a false neutral and floated a valve (or three).

I have not examined my inventory of shims, but I would guess that about half of them are "aftermarket", I don't think that really matters.

.
 
Is there any reason why the OEM shims have a chamfer around the upper and lower edges, whilst the aftermarket shims are straight edged?
 
ged said:
Is there any reason why the OEM shims have a chamfer around the upper and lower edges, whilst the aftermarket shims are straight edged?
Click to expand...

having the chamfer makes it alot easier to flick the shim out using a small flat screw driver some aftermarket shims are a pain to get out
genuine ones seem easier to lift ive found

ozman
 
The first thing I thought when I saw my Z1 shims was through carburising. I don't know even if that is how they are hardened. I no longer have access to a metlab but if I did and a broken shim came across my path I would slip in there and prep it and etch for case depth. I would be concerned if the effective case depth were more than 1/3 of the shim thickness. After that I would be looking for diffusion on the grain boundaries and retained Austenite and and and........ Just saying :)
Anyone know a lab with a back door that accepts beer tokens.
 
Grimly said:
Goddamn, you're a met-head labrat. :)
It never lets go.
Click to expand...
This is true. :) Fortunately I learned that some of the longest life parts when checked at end of life would fail on book criteria for structure and cleanliness. There is no substitute for hands on experience and beating suppliers over the head with an ASME chart is foolish. However there are some lines you don't cross and one of them is case hardening a part to the extent that it has no residual core toughness left to absorb the slings and arrows of real life.
 
Did a couple of years as a trainee met-head labrat with British Steel, right after leaving school. I've forgotten a lot of it, but it was wild and exciting stuff at that age, plodding around the iron and steel works taking samples and doing the analysis real-time for production processes.
Some of my lifetime best pics were taken then. If only I had the kit then that I do now, I could really have done it justice.
 
Bumping this back up in the hope of gathering some more information.

Jeff from Z1 mentioned problems with K&L valve shims in the same timeframe as this thread. http://www.thegsresources.com/_forum/showthread.php?230058-In-search-of-shims&p=2185821#post2185821

I've got a bunch of brand new K&L shims and wondering if there is any definitive way to test them? I checked a bunch of shims on a hardness tester and found a couple that were softer than the others by a fair bit so I'm going to throw those away. Wondering if that's good enough or do I need to do something else?
 
The one that broke on me was an OEM shim. I never had any problems with k&l shims, but that could have been just luck of the draw
 
Nessism said:
Bumping this back up in the hope of gathering some more information.

Jeff from Z1 mentioned problems with K&L valve shims in the same timeframe as this thread. http://www.thegsresources.com/_forum/showthread.php?230058-In-search-of-shims&p=2185821#post2185821


I've got a bunch of brand new K&L shims and wondering if there is any definitive way to test them? I checked a bunch of shims on a hardness tester and found a couple that were softer than the others by a fair bit so I'm going to throw those away. Wondering if that's good enough or do I need to do something else?
Click to expand...


That shim in post #39 and the ones Steve pictured looks to be too hard. Softer shims would probably just wear more and not shatter.
Also any grit or grime under the shim would cause a properly heat treated shim to fail as well.
 
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