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...

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-mic...chanist-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/B0..._m=ATVPDKIKX0DER&pf_rd_r=04JFPQJ2YJBSMT1HQ01Z

 

[hcritz]

I bought one of the digital mics from H.F. Checked it against a high dollar one and it's pretty spot on. It will do inches and MM...so that's nice.
Even came in a nice case with a spare battery.
Was on sale for $39 i think.

 

[mike_of_bbg]

Well, it's really all a matter of personal opinion and analysis in the end, IMO. How accurate do you need and expect it to be, and how OFTEN are you going to use it? I have my $20 digital calipers, and the $10 metric micrometer linked below. Both seem as accurate as anything I've used in the past. The calipers are 6 months old so I can't speak to the battery life yet. But my local dollar store also sells all sorts of button cells including 2032s, 2016s, and LR44s (which IIRC the calipers take) in multi-packs for $1. I'd have to go through a LOT of batteries to reach $130. Not too worried about the battery dying in the micrometer

I bought both tools and used them several times over a 1-week span solely for the purpose of examining my GS550 motor internals, and they've been in a drawer since. If I used calipers/micrometers daily, year-round in my hobbies or work I might well feel differently. But they did very well and I trust them to be accurate. For occasional use I can't imagine a better buy. Maybe I just got lucky, but I'm glad looking back to have the extra $$$ in my pocket.

Having two different measurement tools to compare each other to is also very helpful in developing trust. When micometer measurement = caliper measurement = printed shim or feeler stack size, dead on, every time, that will truly increase confidence more than just shelling out a lot of bucks. No matter what you pay for a measuring tool, compare it to a known control every time you use it!

 

[posplayr]

Well, it's really all a matter of personal opinion and analysis in the end, IMO. How accurate do you need and expect it to be, and how OFTEN are you going to use it? I have my $20 digital calipers, and the $10 metric micrometer linked below. Both seem as accurate as anything I've used in the past. The calipers are 6 months old so I can't speak to the battery life yet. But my local dollar store also sells all sorts of button cells including 2032s, 2016s, and LR44s (which IIRC the calipers take) in multi-packs for $1. I'd have to go through a LOT of batteries to reach $130. Not too worried about the battery dying in the micrometer

I bought both tools and used them several times over a 1-week span solely for the purpose of examining my GS550 motor internals, and they've been in a drawer since. If I used calipers/micrometers daily, year-round in my hobbies or work I might well feel differently. But they did very well and I trust them to be accurate. For occasional use I can't imagine a better buy. Maybe I just got lucky, but I'm glad looking back to have the extra $$$ in my pocket.

Having two different measurement tools to compare each other to is also very helpful in developing trust. When micometer measurement = caliper measurement = printed shim or feeler stack size, dead on, every time, that will truly increase confidence more than just shelling out a lot of bucks. No matter what you pay for a measuring tool, compare it to a known control every time you use it!

A Digital Micrometer that switches inches to mm has been indispensable for me working on these old GS's in the last two years. I dont have one but the HF units while inexpensive seem to fill the bill.

 

[Agemax]

you are all getting way too deep here. if a shim is 2.65mm and your top of the range calipers measure it exactly then fair play, but if your $30 calipers measure it at 2.643mm then so what? you are still gonna be well within the tolerances of the suzuki recommendations. lets face it some racers set their valve clearances wide as a benchmark anyway, some set em tight!
a few hundredths of a mm aint gonna change the way your bike runs

 

[makr]

you are all getting way too deep here. if a shim is 2.65mm and your top of the range calipers measure it exactly then fair play, but if your $30 calipers measure it at 2.643mm then so what? you are still gonna be well within the tolerances of the suzuki recommendations. lets face it some racers set their valve clearances wide as a benchmark anyway, some set em tight!
a few hundredths of a mm aint gonna change the way your bike runs

Dude, please dont take the fun out of a bunch of geeks talking tools. Geez


Personally am a micrometer fan. Olde school vernier, not digital. I have both, just like the olde school way.