BE-FAQ - Bearing measurement marks

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Let me explain why BE Bearings have marks on the surface.

Every BE Bearing is hand measured. The measurement process uses a data logging Mitutoyo drop indicator with a rounded roller bearing tip (P/N: 543-562ACAL). The roller bearing tip is like a wheel that rolls over the surface of the bearing while it measures the bearing thickness. This process leaves a visible mark on the surface of the bearing. The marks left by this process are totally harmless, and you will never be able to feel them with your fingers or measure them with a measuring device.

During the measuring process, after they are measured, each shell is sorted and placed in bins according to every 0.00005 inch difference. The measuring, sorting, and binning allows us to take advantage of the normal distribution curve of bearing thicknesses to create perfectly matched sets of bearings for each customer. Once the bearings are sorted and binned, they are then used to create matched sets. This article describes how we mix and match individual shells to create perfectly matched sets of bearings.

All bearings measured with the new Mahr air gauge will not have marks on them. See the Q&A below for an explanation. These bearings are only available after March, 2023.


Q: Does this process hurt the bearings?
A: No, the marks are only on the surface and do not cause any damage to the shells. You can't even feel them or measure them with other measuring devices.

Q: What if I want a set that doesn't have these marks? Can I get a set that isn't measured?
A: Yes, upon special request, you may obtain a set of bearings that are not measured. However, you might wait a while because all shells are measured when they arrive, and you would have to wait until a future shipment to obtain an unmeasured set. We do not advise doing this. Since the issue of the S65 bearing clearances is exacerbated by tolerance stacking, measuring, sorting, binning, and creating matched set of bearings is the only way to eliminate the bearings themselves from contributing to the bearing clearance problem. If you do decide that you want a set of BE Bearings that hasn't been measured, then you will be giving up the engine replacement warranty offered by BE Bearings. That engine replacement warranty is described here.

Q: Has BE Bearings always measured their shells?
A: Yes, kind of. Since the second batch received, BE Bearings has always measured their shells.

  1. In 2015, the first shells were measured with a Mitutoyo ball-anvil micrometer. This device seemed like a good idea, but proved too time consuming and did not produce repeatable results. Measuring each shell took approximately 21 seconds.
  2. The second device was a Mitutoyo 543-562A drop indicator with a ball-shaped tip. This device is accurate to 0.00005 inch with resolution to 0.00002 inch. This device has been used since 2017. This device proved very reliable and repeatable. The ball-shaped tip seemed to scrape the shells a little more than desired and was eventually replaced. Measuring each shell took approximately 7.5 seconds.
  3. More recently, the ball-shaped tip was replaced with a rounded roller bearing. The roller bearing does not scrape the bearing surface, but does still leave visible marks. There are no harm caused by these marks and they cannot be felt by your fingers or measured with any device that you may have. Measuring each shell takes approximately 6.0 seconds.
  4. Starting March 2023, a new device will be used. A custom-made Mahr air gage will be used to measure BE Bearings. This new device is accurate to 0.0000005 inch, with resolution. Bearings will be measured to 0.00001 inch (1/100,000 of an inch) and rounded up to 0.00005 for sorting and binning parts. This new air gage will use differential air pressure to measure the bearing thicknesses. The new air gage be able to measure, sort, and bin each shell in approximately 6.5 - 7.0 seconds.

Q: Now that I'm used to seeing these measurement marks on my bearings, why don't my new bearings have any marks on them? Did BE forget to measure them?
A: All bearings measured after March, 2023 will not have marks on them. The new Mahr air gage does not leave any marks. BE did not forget to measure them.