Shim Measurement 101

Please refer to the shim measurement instructions in our Maintenance Guides for sale on this Site.

  1. We sell shims from several different vendors, Ducati OEM shims being among them. 
  2. All shims are lapped to ensure flat surfaces. This makes any size markings on Ducati OEM shims irrelevant. Likewise customers should NEVER use shim markings on the side of shims to be the genuine thickness. Even on un-lapped shims, Ducati side markings can be off up to .05mm
  3. We use high quality Mitutoyo digital calipers and micrometer measuring gauges. 
  4. All instruments are verified by a known thickness prior to measuring each shim, in this case a 10mm Mitutoyo stock of steel. 
  5. Closer shim measurement tools are verified using a Mitutoyo drop gauge prior to use. 
  6. All shims are re-measured prior to shipment to ensure accuracy. 
  7. Differences in tension on measurement gauges can create differences in measurements as great as .05mm. That means two different people measuring the same shim with the same equipment can have differences in measurements. 
  8. Please realize that .05mm is thinner than the thickness of a human hair. It doesn’t take much for your measurements to differ from ours. 
  9. We recommend that customers purchase shim kits rather than individual shims to avoid delays in services. 
  10. Closer shim measurement tools wear at a rate of approximately .005mm every 150 measurements. Even though they are hardened tool grade steel, so are the shims. Metal on metal contact during measurement results in wear. Unless you have the proprietary bench tool I have for measuring closer shim offsets, there is no way for users to determine wear. I include a piece of paper with each tool that measures the tools to 3 decimal places at time of shipment.
  11. Should customers purchase individual shims, we recommend purchasing one size larger and one size smaller (bracketing) in addition to the thickness needed to prevent potential discrepancies in measurements from disrupting the timing to your valve service. Bracketing your sizes when ordering may cost you a few more shims, but will save in the long run in terms of time and postage expenses.  

NOTE: If customers fail to “bracket” shim orders and find our shims measurements are different than their readings they may return shims for exchange but we will not ship out additional shims without a return of any shims in question to verify discrepancies in measurements. Nor will we get into arguments about whose measurements are more accurate. Again, customers are encouraged to “bracket” their shim orders to account for discrepancies in measuring instruments and measuring techniques. 

An Example:

An example will illustrate discrepencies with shim sizes.

Customer: Hi I ordered a 3.00 but was sent a 3.05 shim.

Desmo Times: I notice that you didn’t bracket your order. Shim tools/measurement techniques can result in discrepancies as great as .05mm.

Customer: I thought the shim sizes would be exact.

Desmo Times: No machine shop can make shims to a precision of 1/100th of a millimeter. Even Ducati OEM shims can vary by as much as .05mm. That means when you order a 3.00mm shim I will ship one that measures between 3.00 and 3.04. We aren’t measuring tire sizes here. The difference between a 3.00 and 3.04mm shim is about 1/2 the thickness of a human hair. So if I measure it at 3.04mm and you measure it at 3.05mm I get an email with a complaint. But if you would have ordered a 2.95mm , a 3.00 and a 3.05mm you ensure you get the shim you need. Better yet, order a shim kit so there isn’t an issue in relying on a single shim.