Semi-Sphere Valve Shims only in 0.05mm increments - Camhead

I'm trying to get all the valves on my '13 GSA to the same clearance values, but I'm running into a situation I was not expecting. Shims from the factory run in 0.025mm increments, but BMW only sells shims in 0.05mm increments...

I'm not quite following the logic that the factory has the 0.025mm increments, but they're unavailable for the consumer to purchase through the dealer.

If anyone has a 5.375mm shim at the ready, I'd be happy to donate a few bucks to get it from you.

-acs

Pesky problem isn't it. .025mm is only .00098" or about .001" getting pretty close to splitting hairs. I guess they just did not want to stock all those extra shims to the dealers. If you have some relationship with your dealer service department there is a chance one of the techs has the shim in his used but good drawer.

IIRC the K-series uses the same shims, but in smaller increments. Check the fiche.

I'll have to give a call back to the dealer. A box of donuts may in order...

It is definitely splitting hairs at this point as I can get all of my clearances in spec with 0.05mm increment of the shims, but then I'm one shim short of having all the intake clearances at 0.18mm. I know... It's a sickness.

You are correct Jim. I looks like the K1200 and K1300 both share the cam head semi-sphere valve shims. Unfortunately they share the same part numbers and 0.5mm increments.

Not sickness my friend. Sick is when you order metric feeler gauges to give a true clearance reading in 0.010mm steps, instead of using inch with metric conversions in 0.025mm steps. Ask me how I know.

But I digress. I assume you are targeting the middle of the clearance spec for your shim size? Go to shim the next size down and live with slightly more clearance than you targeted, but is still well within specs.

Bill, you mean you don't have a Nm only torque wrench? in reality I don't see anything wrong with metric feeler gauges, & I double check (complete waste of time it seems) all my shims with a metric caliper. Use metric micrometer to check disk thickness etc. .

Where are you guys buying true metric feeler gauges?...I've been looking for a set.

Thanks!

I bought a set made by FACOM several years ago, for maybe $20-25. Snap-On and Mac surely offer a set. Mine are a plain-jane model, but they're offered in magnetic, anti-magnetic, angled, etc.

0.05mm increments is how it has been for 30 years, since the introduction of the K100.

Amazon has a good Proto set that measures to 10 micron steps (.010mm) or a half thou approx. $14.35

1/2-inch x 3-5/16-inch metric blades in steel holder
Sizes: 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, thru 1.00mm

http://www.amazon.com/gp/product/B001HWADG6/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1

Nope, never sprung for the NM wrench cuz I use Snap On tools. Maybe if I worked for the US government I could have afforded it .

I just do the conversion. But.... I do use metric mikes to save conversion time when machining.

Actually, if you want to record the actual clearance (I typically do this for shimmed valve trains) you pretty much need to have that variety. I use a set from BMW that has every 0.02 plus the 5s. It's really nice but a bit expensive; word was that Yamaha sold the same set for a lot less. I haven't needed to look for another one but I should. BMW also has a 0.03~0.10 set that was intended for the F650s.

The BMW ones are longer than the ones shown in the Amazon link. Long enough to go under both intakes or exhausts on an Oilhead.

1 mm = .0393blah"
.5mm = .0196blah"
.05mm= .001blah"
.025mm= .0009blah"

So in other words, you're worried about getting clearances exactly on -some number-, instead of the number that is one thousandth of an inch away from that number?

...a crusty old journeyman toolmaker to me, the lowly apprentice...

"Knowing the difference between a circus tent and a tenth will get you a long way in life"

Hey Mr. ohgood, I think yer sayin' 0.001" is close enough? I agree.

Most of can't tell the difference between 0.0010" and 0.0015" with a feeler gauge anyway.

BTW, I would opt toward loose rather than tight, just for arguments sake.

Consistently the same is more important than exactly on target at .00001 tolerance.

Does not compute. I don't believe the given description as it implies that it covers 96 steps (from .04mm to 1.00mm) but the set is only 25 blades.

Yep... that set goes to 0.10 mm then jumps in .05 mm increment to 1.0mm. Not bad for those who have to have exact metric. I use a set that goes in .001" steps and is also marked with metric values. Close enough for valve shims.

That's what I'm going for - all the same clearances... It's just one intake valve that's going to be slightly off from the others.

Ex R upper 0.36mm
Ex R lower 0.36mm
Ex L upper 0.36mm
Ex L lower 0.36mm
In R upper 0.18mm
In R lower 0.20mm
In L upper 0.18mm
In L lower 0.18mm

Ultimately, I'm working beyond the precision of my measuring device... Factor that in with the error from the accuracy of my measurements and I'm probably getting no benefit from my work. The difference in measurement is really only 0.0007"... Maybe I'm going too far in trying to make things perfect.

Ok...here's how to compute metric gaps 101.

You are trying to measure a gap of 0.800mm. The 0.750mm feeler goes in but the 0.800 does not. So you have a possible gap measurement error between 0.0mm and 0.050mm (0 to .002 thou).

So you take the 0.700mm blade and stack the 0.060mm with it and check the gap. It goes in so you know the gap is over 0.760mm. You keep adding 0.010 step blades to the 0.700mm blade until it does not go in the gap, say it was .700 + .090 = 0.790mm.

Now you have a truly accurate measurement of the gap (between 0.780mm and 0.790mm) and nailed the gap error down to 10 microns (or half a thou) . Stacking blades gives you many more sizes than the number of feelers supplied. Can you see how it works now?

In theory. In practice it doesn't work for me. Oh, I can stack two (or more) blades but when I try to slip the nose of the stack into the item to be measured there is a good chance that I'll mess up the thinner blade. BTDT Might be a personal failing.