{"id":565,"date":"2026-10-21T17:07:03","date_gmt":"2026-10-21T09:07:03","guid":{"rendered":"http:\/\/www.amico-in-affitto.com\/blog\/?p=565"},"modified":"2026-10-21T17:07:03","modified_gmt":"2026-10-21T09:07:03","slug":"how-to-measure-the-clearance-of-babbitt-journal-bearings-4586-745b6f","status":"publish","type":"post","link":"http:\/\/www.amico-in-affitto.com\/blog\/2026\/10\/21\/how-to-measure-the-clearance-of-babbitt-journal-bearings-4586-745b6f\/","title":{"rendered":"How to measure the clearance of Babbitt journal bearings?"},"content":{"rendered":"

If you\u2019ve ever worked with rotating equipment\u2014whether it\u2019s a large industrial pump, a steam turbine, a paper mill dryer, or a heavy-duty compressor\u2014you know how critical Babbitt journal bearings are to keeping that equipment running smoothly. As a Babbitt journal bearing supplier with 18 years of experience, I\u2019ve seen firsthand that even a tiny miscalculation in bearing clearance can turn a seemingly minor maintenance issue into a catastrophic breakdown. Last year, we had a customer send us a failed bearing that caused their entire production line to shut down for 72 hours; the root cause? They had guessed at the clearance instead of measuring it properly during a bearing replacement. That\u2019s why I\u2019m writing this today: to walk you through exactly how to measure Babbitt journal bearing clearance the right way, with the hands-on, real-world tips I\u2019ve picked up over decades of working with these components. No theory-heavy jargon, no shortcuts\u2014just the process that saves our customers from downtime and costly repairs. Babbitt Journal Bearings<\/a><\/p>\n

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First, let\u2019s get on the same page about what bearing clearance actually is, because this isn\u2019t some arbitrary number. Babbitt journal bearings are split (most are, for easy installation) liners made of soft, tin or lead-based Babbitt metal that sits around a rotating shaft. Clearance is the tiny, intentional gap between the inner surface of the Babbitt liner and the outer surface of the shaft. This gap isn\u2019t a flaw\u2014it\u2019s a feature: it holds a thin film of lubricant that keeps the shaft and Babbitt from touching, which prevents wear, reduces friction, and dissipates heat. Get the clearance wrong, though, and you\u2019re in trouble. If clearance is too small, the lubricant film can\u2019t form; the shaft and Babbitt grind together, melting the soft Babbitt metal, and you\u2019ll get what\u2019s called a \u201cwipe\u201d or a \u201cscuff\u201d failure. If clearance is too large, the shaft can wobble or shift excessively, which causes vibration, noise, and even misalignment issues that damage seals, couplings, and other nearby components.<\/p>\n

The first step to measuring clearance is knowing what the correct target clearance should be for your specific bearing and application. That\u2019s where most people skip a critical step: they grab a random bearing gauge and start measuring, without checking the manufacturer\u2019s specifications (or, if you\u2019re replacing a bearing, the original equipment manufacturer\u2019s (OEM) guidelines). For our bearings, we provide a clearance table with every shipment, tailored to the shaft diameter and load rating of the bearing. As a general rule of thumb, the ideal radial clearance for Babbitt journal bearings is usually between 0.001 and 0.002 times the shaft diameter, but this can shift dramatically depending on the load, speed, and operating temperature. For example, a high-speed turbine (running at 10,000 RPM or more) needs a larger clearance to account for thermal expansion of both the shaft and the Babbitt liner. A slow-speed, heavy-duty crusher bearing, on the other hand, needs a tighter clearance to prevent excessive wobble under constant heavy load. Always confirm the target clearance before you start measuring\u2014don\u2019t guess.<\/p>\n

Now, let\u2019s talk about the tools you\u2019ll need. You don\u2019t need a fancy lab setup, but you do need the right tools to get accurate readings. Here\u2019s my go-to kit for every bearing clearance measurement job:<\/p>\n

    \n
  1. A outside micrometer, calibrated within the last 12 months, to measure the shaft diameter. This is non-negotiable\u2014if your micrometer is off, your clearance calculation will be off. I keep two calibrated micrometers on my truck: one for shafts under 6 inches, one for larger diameters.<\/li>\n
  2. Feeler gauges (also called feeler strips) of varying thicknesses, ranging from 0.001 inches to 0.015 inches, with narrow, pointed ends for getting into tight gaps.<\/li>\n
  3. Plastigauge, a soft, plastic (polyethylene) strip that compresses evenly when pressure is applied\u2014this is the most reliable method for measuring clearance on assembled bearings, and it\u2019s something I recommend to every customer.<\/li>\n
  4. A dial bore gauge, if you have access to one, for measuring the inner diameter of the Babbitt bearing. This is ideal for new bearings before installation, but Plastigauge works just as well for most field applications.<\/li>\n
  5. Safety gear: work gloves, safety glasses, and a clean rag\u2014you don\u2019t want dust or oil messing up your measurements, or getting in your eyes while you\u2019re working.<\/li>\n<\/ol>\n

    Before you start measuring, you have to prepare the bearing and shaft properly. If you\u2019re working on a disassembled component, take your time to clean both the shaft surface and the inner Babbitt surface of the bearing with a lint-free cloth and isopropyl alcohol. Any tiny bit of dirt, metal shavings, or old lubricant will throw off your readings, or even scratch the Babbitt liner. If you\u2019re working on an assembled bearing (installed in a housing on site), make sure the shaft is free of burrs or corrosion in the area where the bearing sits. Even a tiny burr the size of a grain of sand can make your measurement look larger than it actually is. Also, make sure the bearing housing is clean and free of debris\u2014if the bearing is sitting crooked in the housing, your clearance measurement will be wrong.<\/p>\n

    Now, let\u2019s get to the actual measurement methods. I\u2019m going to cover the two most common, reliable methods: Plastigauge measurement (for assembled, installed bearings) and bore gauge micrometer measurement (for new or disassembled bearings). I use Plastigauge 90% of the time in the field, because it\u2019s quick, and it gives a direct reading right on the job.<\/p>\n

    Let\u2019s start with Plastigauge, since that\u2019s what I teach our customers first. Here\u2019s the step-by-step process I follow every time:<\/p>\n

      \n
    1. First, confirm your target clearance and gather your tools. Make sure the shaft and bearing are clean and dry.<\/li>\n
    2. Carefully remove any lubricant from the area where you\u2019ll apply the Plastigauge. Oil will soften the plastic strip, leading to an inaccurate measurement. A quick wipe with a dry lint-free cloth is all you need.<\/li>\n
    3. Take a piece of Plastigauge, and cut it to the length of the bearing\u2019s inner surface (about \u00bd inch shorter than the bearing\u2019s total length, so it doesn\u2019t stick out the ends). Place the Plastigauge strip directly on the top of the shaft, along the center line\u2014don\u2019t twist it or fold it, just lay it flat.<\/li>\n
    4. Now, carefully install the bearing cap (the top half of the split bearing) back onto the housing, and torque the cap bolts to the manufacturer\u2019s specified torque. This is another critical step: over-torquing will compress the Plastigauge too much, giving you a false low clearance reading; under-torquing will leave the Plastigauge too loose, giving you a false high reading. I always use a torque wrench for this, and I double-check the torque setting against the OEM guidelines or our bearing specs.<\/li>\n
    5. Once the bolts are torqued, carefully remove the bearing cap (don\u2019t move the Plastigauge\u2014if it shifts, you have to start over). You\u2019ll see a flattened piece of plastic where the strip was.<\/li>\n
    6. Now, take the Plastigauge scale that comes with the kit. Compare the width of the flattened Plastigauge to the printed lines on the scale. The number that matches the width of the compressed plastic is your actual radial clearance. Write that number down\u2014this is the reading you\u2019ll compare to your target clearance.<\/li>\n
    7. If you need to, you can rotate the shaft a few times and take a second measurement at 90 degrees, just to confirm you didn\u2019t have any uneven compression from the bearing cap. If the two measurements are more than 0.001 inches apart, you probably have a bent shaft or a misaligned bearing, and you should investigate further before proceeding.<\/li>\n<\/ol>\n

      The second method is using a dial bore gauge and outside micrometer, which is great for new bearings before installation, or for taking precise measurements on disassembled components. Here\u2019s how that works:<\/p>\n

        \n
      1. Measure the shaft diameter with your calibrated outside micrometer, at three different points along the shaft and at two different angles (0 degrees and 90 degrees) to account for any shaft ovality. Take the average of these six readings\u2014this is your average shaft diameter.<\/li>\n
      2. Set up your dial bore gauge: calibrate it by measuring a standard gauge block that matches the approximate inner diameter of your bearing. This ensures your gauge is accurate.<\/li>\n
      3. Insert the dial bore gauge into the Babbitt bearing\u2019s inner liner, and take the same set of measurements: three points along the bearing length, two angles. Take the average of these six readings\u2014this is your average bearing inner diameter.<\/li>\n
      4. To calculate radial clearance, subtract the average shaft diameter from the average bearing inner diameter. That gives you the total radial clearance (the gap between the shaft and the bearing). For example, if your average shaft diameter is 2.000 inches, and your average bearing inner diameter is 2.004 inches, your radial clearance is 0.004 inches.<\/li>\n<\/ol>\n

        Now, let\u2019s talk about common mistakes I see all the time, because these are the things that lead to bad measurements and failure. First, using a dirty shaft or bearing. I once watched a mechanic skip cleaning a bearing for a power plant pump, and the Plastigauge had a tiny metal shaving under it that made the clearance read 0.006 inches, when the actual clearance was only 0.003 inches. He installed the bearing, and it seized up 2 hours later, costing the plant $120,000 in downtime. Cleanliness isn\u2019t optional\u2014it\u2019s half the battle. Second, over-torquing or under-torquing the bearing cap when using Plastigauge. I always tell customers to use a torque wrench, and to follow the exact torque sequence (usually crisscross, to apply even pressure) listed in the manual. Third, using a worn or uncalibrated micrometer. If your micrometer has a zero error (like it reads 0.001 inches when it\u2019s closed completely), every measurement you take will be off by that 0.001 inches. I calibrate my tools every quarter, and I check them with a standard gauge block before every job. Fourth, guessing at target clearance. Last year, a construction company called us because their new bearing was making noise. They had used the \u201c0.001 per inch\u201d rule, but their bearing was for a high-speed generator, which needs 0.0015 per inch of shaft diameter. Their clearance was too tight, and the Babbitt was already starting to scuff. We sent them a replacement bearing with the correct clearance, and they haven\u2019t had an issue since.<\/p>\n

        Once you\u2019ve measured the clearance, what do you do next? If the measurement is within your target range, you\u2019re good to go\u2014you can lubricate the bearing and install it. If it\u2019s too small, you\u2019ll need to either re-machine the bearing housing (if it\u2019s an oversized housing) or get a new bearing. If it\u2019s too large, you can either install a thicker Babbitt bearing or, for some applications, add a shim, but I always recommend replacing the bearing if clearance is more than 0.002 inches over the target, because excessive clearance leads to vibration and wear that will ruin nearby components.<\/p>\n

        As a Babbitt journal bearing supplier, my job isn\u2019t just to send you a high-quality bearing\u2014it\u2019s to make sure it\u2019s installed correctly, so it works as intended. That\u2019s why I\u2019ve spent years refining this process, because I\u2019ve seen the cost of getting clearance wrong, first hand. Every bearing I ship comes with a clear clearance recommendation based on its application, and I\u2019m always here to answer questions if you\u2019re unsure about measurements on a job.<\/p>\n

        At the end of the day, measuring Babbitt journal bearing clearance isn\u2019t rocket science, but it requires care, attention to detail, and using the right tools and methods. Skipping a step, guessing at numbers, or using dirty parts can lead to costly downtime, damaged equipment, and even safety issues. Whether you\u2019re a maintenance technician, a plant manager, or someone who works with rotating equipment, taking the time to measure clearance correctly is one of the most important things you can do to keep your equipment running smoothly.<\/p>\n

        <\/p>\n

        If you have questions about measuring clearance for your specific Babbitt journal bearing application, or if you need a custom bearing for your equipment, feel free to reach out to our team. We have years of experience working with all types of industrial equipment, and we\u2019re happy to help you get the right bearing and the right measurement process for your needs.<\/p>\n

        Thin Walled Babbitt Bearings<\/a> References:<\/p>\n

          \n
        1. Stout, K. J., and Domblesky, J. P. (2000). Tribology for Engineers. CRC Press.<\/li>\n
        2. American Society of Mechanical Engineers (ASME). (2017). Standard for Journal Bearings for Industrial Machinery. ASME Press.<\/li>\n
        3. Neale, M. J. (Ed.). (2001). Tribology Handbook, 2nd Edition. Butterworth-Heinemann.<\/li>\n
        4. Babbitt Bearing Manufacturers Association (BBMA). (2019). Installation and Maintenance Guidelines for Babbitt Journal Bearings. BBMA Technical Bulletin.<\/li>\n<\/ol>\n
          \n

          Wenzhou Zhengbang Bearing Co., Ltd.<\/a>
          We are one of the most professional babbitt journal bearings manufacturers and suppliers in China. With abundant experience, we warmly welcome you to buy customized babbitt journal bearings at competitive price from our factory. If you have any enquiry about free sample, please feel free to email us.
          Address: Units 1-1 and 3-1, Building 12, Yongxing Nanyuan Small and Micro Enterprise Startup Park, Binhai 2nd Road, Yongxing Subdistrict, Longwan District, Wenzhou City, Zhejiang Province.
          E-mail: zbbearing@zbbearing.com
          WebSite:           https:\/\/www.zb-bearings.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

          If you\u2019ve ever worked with rotating equipment\u2014whether it\u2019s a large industrial pump, a steam turbine, a … How to measure the clearance of Babbitt journal bearings?<\/span>Read more<\/a><\/p>\n","protected":false},"author":304,"featured_media":565,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[528],"class_list":["post-565","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-babbitt-journal-bearings-4f0e-749772"],"_links":{"self":[{"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/posts\/565","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/users\/304"}],"replies":[{"embeddable":true,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/comments?post=565"}],"version-history":[{"count":0,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/posts\/565\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/posts\/565"}],"wp:attachment":[{"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/media?parent=565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/categories?post=565"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.amico-in-affitto.com\/blog\/wp-json\/wp\/v2\/tags?post=565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}