Accurately measuring thickness of shim

[Johnny K]

Looked up in the search forum but couldn't find an answer. I have a digital caliper and have done valve adjustments. My question is when I am measuring the thickness of the shim with my caliper, should i make a real good snug fit or just a light fit on the shim. Almost all of my shims are not numbered but have put them in tiny clear bags with labels on the bag itself. Just not sure how much pressure to measure with. Would a micrometer be more accurate?

[Ponderosa]

Caliper vs Micrometer...

The Micrometer will be more accurate, as you can measure at wear point, center of shim. But a caliper will do, I used both and got very little difference, usually then mark them with magic marker if original marking is gone..

[Agemax]

neither will be completely accurate unless they are calibrated. but they should give you a reasonably good measurement for your needs as shimming has a tolerance so a few hundredths of a millimetre wont affect your clearances

[Nessism]

I use a micrometer to measure my shims since there is production variation between them and the shims are labeled to some rounded off increment. If you have a good selection of shims, many times you can find one to get the clearance ‘just right” when installed. A high quality set of calipers can be used as well but in my experience, a micrometer is the right tool for the job.

[posplayr]

Use your caliper to measure a feeler gauge to get a feel for pressure sensitivity

[bwringer]

To get the feel for how hard to press and for the repeatability and calibration of your calipers, measure a few shims of known size -- ones with a marking you can read.

I use a set of cheepo digital calipers (the ones you can get at Harbor Freight for <$20) and they work great. Really. (Hint: if they're squirrely, change the battery.)

I used to use a micrometer, but it's slow and converting barleycorns to mm was getting on my nerves. I flippin' hate inches, and it seems that metric micrometers all cost $200.

However, I did see a digital micrometer in HF the other day for about $40...

[gggGary]

I'm with the digital caliper is fine and these tolerances aren't critical. Hint I have a large set of shims and no 8 valve motors to shim anymore. Maybe 40 shims total................ Sold to a good offer, Thanks Todd!

[mike_of_bbg]

I used to use a micrometer, but it's slow and converting barleycorns to mm was getting on my nerves. I flippin' hate inches, and it seems that metric micrometers all cost $200.

However, I did see a digital micrometer in HF the other day for about $40...

http://www.sourcingmap.com/25mm-micrometer-caliper-gauge-mechanist-measure-tool-silver-black-p-2568.html

and while you're at it:

http://www.sourcingmap.com/steel-metric-thickness-feeler-gage-gauge-002100mm-p-21339.html

Though that .02mm feeler is like foil If you google you should be able to find a free shipping or $3 off coupon code for sourcingmap.com.

I found my digital caliper was pretty much dead on with that micrometer, and both were within .01mm of the printed shim sizes on those where the printing was still readable.

[Dave8338]

I think it all is determined by the quality of the tool your using.

Money spent on high quality mics or calipers, is money well spent.

[Suzuki_Don]

(Hint: if they're squirrely, change the battery.)

Jim, --- SQUIRRELY

Explanation please!!!!!!!!!!!!!!!

[posplayr]

Jim, --- SQUIRRELY

Explanation please!!!!!!!!!!!!!!!

The digital caliper display gets erratic when the battery gets low.

[hampshirehog]

The digital caliper display gets erratic when the battery gets low.

Glad that one's cleared up - I was imagining it starting pinching your nuts

[bwringer]

Glad that one's cleared up - I was imagining it starting pinching your nuts

Any pinching would be operator error...

[Nessism]

I bought two sets of those $16 Harbor Freight calipers (they are knock offs of the well respected Mitutoyo #500-196-20) and they went though the battery in very short order. Replaced the battery, no big deal, but it was dead again in only a matter of months so obviously the electronic mechanism is power hungry. The real Mitutoyo's have excellent battery life, measured in years, not months, so apparently it's not a free lunch getting those HF imitations. One of my HF calipers is still working great but the other is a little buggy, after I dropped it, go figure. I also bought a set of the real Mitutoyo digitals and some mechanical Mitutoya dial calipers (which are my hands down favorite). The digitals are nice to jump between inches and metric but those mechanical calipers are a thing of beauty - solid feeling and they always go back to exactly zero, unlike the digitals which often hang up in between zero and the first increment due to round off error.

Regarding measuring shims, any half way decent micrometer will measure in .0001" increments which is 10 times more accurate than a pair of calipers. Since shims are only about .002" between steps, the micrometer is the tool to use if you want to hone in on those shims that are between the steps.

Seems funny to write all this anal drivel about splitting steps between shims since so many folks around here refuse to even check their valves. As long as their bike starts they ride. Maybe people like me should learn a lesson going the other way?

[posplayr]

I bought two sets of those $16 Harbor Freight calipers (they are knock offs of the well respected Mitutoyo #500-196-20) and they went though the battery in very short order. Replaced the battery, no big deal, but it was dead again in only a matter of months so obviously the electronic mechanism is power hungry. The real Mitutoyo's have excellent battery life, measured in years, not months, so apparently it's not a free lunch getting those HF imitations. One of my HF calipers is still working great but the other is a little buggy, after I dropped it, go figure. I also bought a set of the real Mitutoyo digitals and some mechanical Mitutoya dial calipers (which are my hands down favorite). The digitals are nice to jump between inches and metric but those mechanical calipers are a thing of beauty - solid feeling and they always go back to exactly zero, unlike the digitals which often hang up in between zero and the first increment due to round off error.

Regarding measuring shims, any half way decent micrometer will measure in .0001" increments which is 10 times more accurate than a pair of calipers. Since shims are only about .002" between steps, the micrometer is the tool to use if you want to hone in on those shims that are between the steps.

Seems funny to write all this anal drivel about splitting steps between shims since so many folks around here refuse to even check their valves. As long as their bike starts they ride. Maybe people like me should learn a lesson going the other way?

Well to continue that thought;

I have a Central Tool #6425 (Made in US with Swiss electronics) and have been amazed at how I can take a feeler guage out and this thing nails the thickness weather 0.010", 0.040" or whatever. Battery life is amazing considering I leave it on 1/2 the time.

Holey Crap this think costs $300 bucks !!! I remember spending less than $100 maybe $120

http://www.handsontools.com/Central-6425-Electronic-Digital-Caliper_p_6930.html

Well I bought my brother the equivalent for less than $20 and worked almost as well. The main difference is the #6425 has 1/2 of a 1/1000" resolution and comes up with and extra 1/2 digit, the HF model is limited to 1/1000" resolution. I don't know about it's battery longevity

This is the model Ed is referring to.

http://www.amazon.com/gp/product/B001C0ZPNO/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000RUA6LQ&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=04JFPQJ2YJBSMT1HQ01Z