{"id":17136,"date":"2026-06-05T09:56:12","date_gmt":"2026-06-05T00:56:12","guid":{"rendered":"https:\/\/tsrjp.com\/en\/?post_type=tips&#038;p=17136"},"modified":"2026-06-12T11:39:54","modified_gmt":"2026-06-12T02:39:54","slug":"blog27","status":"publish","type":"tips","link":"https:\/\/tsrjp.com\/en\/tips\/blog27\/","title":{"rendered":"Grade 1 Bolt Conversion and Its Effects."},"content":{"rendered":"\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">Threads are classified by \u201cgrades.\u201d<br>Simply put, these grades are standards used to control the amount of clearance and play between mating threads. In Japan, thread grades are generally classified as follows:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-small-font-size\">Grade 1 \u2192 Minimal clearance and play<\/li>\n\n\n\n<li class=\"has-small-font-size\">Grade 2 \u2192 Standard general-purpose fit<\/li>\n\n\n\n<li class=\"has-small-font-size\">Grade 3 \u2192 Larger clearance between threads<\/li>\n<\/ul>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">It should be noted that Grade 2 threads are used in the vast majority of industrial products, including motorcycles and automobiles.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"1536\" height=\"1025\" src=\"https:\/\/tsrjp.com\/en\/wp-content\/uploads\/2024\/07\/20240720-P1112939-1536x1025-1.webp\" alt=\"\" class=\"wp-image-2585\" srcset=\"https:\/\/tsrjp.com\/en\/wp-content\/uploads\/2024\/07\/20240720-P1112939-1536x1025-1.webp 1536w, https:\/\/tsrjp.com\/en\/wp-content\/uploads\/2024\/07\/20240720-P1112939-1536x1025-1-300x200.webp 300w, https:\/\/tsrjp.com\/en\/wp-content\/uploads\/2024\/07\/20240720-P1112939-1536x1025-1-1024x683.webp 1024w, https:\/\/tsrjp.com\/en\/wp-content\/uploads\/2024\/07\/20240720-P1112939-1536x1025-1-768x513.webp 768w\" sizes=\"(max-width: 1536px) 100vw, 1536px\" \/><\/figure>\n\n\n\n<h3 class=\"wp-block-heading u-mb-ctrl u-mb-10\">Did You Know? A Grade 1 Bolt Can Actually Fit a Grade 2 Threaded Hole!?<\/h3>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">In general, bolts and threaded holes are designed to be used with the same thread grade. However, in practice, it is possible to install a Grade 1 bolt into a Grade 2 threaded hole.<\/p>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">In fact, we at moto rockman initially considered manufacturing our products with Grade 1 threads. The reasoning was simple: reducing thread clearance could help minimize positional variation and runout.<\/p>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">However, after evaluating and testing the idea in real-world applications, we found that the concept offered not only advantages but also several drawbacks.<\/p>\n\n\n\n<h3 class=\"wp-block-heading u-mb-ctrl u-mb-10\">Grade 1 Threads Do Not Necessarily Mean Higher Performance.<\/h3>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">As thread clearance decreases with a Grade 1 thread, surface contact and friction increase. As a result, issues such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-small-font-size\">Galling (thread seizure)<\/li>\n\n\n\n<li class=\"has-small-font-size\">Reduced ease of assembly<\/li>\n\n\n\n<li class=\"has-small-font-size\">Poorer serviceability<\/li>\n<\/ul>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">become more likely to occur. This is especially problematic when threading into aluminum components.<\/p>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">And perhaps the biggest issue of all is cost.<br>The manufacturing process itself is not significantly different between Grade 1 and Grade 2 threads. However, most thread-rolling equipment is set up and managed around Grade 2 specifications because they are the industry standard. Adjusting production specifically to achieve Grade 1 tolerances for a single customer inevitably leads to a substantial increase in manufacturing cost.<\/p>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">There is another important point as well. Even if thread clearance is reduced, clamping force does not increase. The clamping force generated by a threaded fastener is primarily determined by four factors:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-small-font-size\">Friction<\/li>\n\n\n\n<li class=\"has-small-font-size\">Lubrication condition<\/li>\n\n\n\n<li class=\"has-small-font-size\">Seating surface condition<\/li>\n\n\n\n<li class=\"has-small-font-size\">Tightening torque<\/li>\n<\/ul>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">The slight increase in friction caused by a Grade 1 thread has very little effect on actual clamping force. For that reason, switching to Grade 1 threads does not change the specified tightening torque.<\/p>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">In fact, proper lubrication generally has a far greater influence on fastening performance than thread grade. We\u2019ll cover that topic in more detail another time.<\/p>\n\n\n\n<h3 class=\"wp-block-heading u-mb-ctrl u-mb-10\">What Is the Role of a Bolt?<\/h3>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">Reducing clearance can certainly improve precision.<br>But if that\u2019s true, why aren\u2019t Grade 1 threads commonly used in engines, where accuracy is critical?<br>The answer is simple: that job belongs to the dowel pins.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Bolts<\/strong> \u2192 Provide clamping force<\/li>\n\n\n\n<li class=\"u-mb-ctrl u-mb-10\"><strong>Pins<\/strong> \u2192 Provide positioning accuracy<\/li>\n<\/ul>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">Each component has its own role.<br>If you try to achieve positioning accuracy through the threads alone, you end up introducing other problems, such as:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-small-font-size\">Reduced assembly efficiency<\/li>\n\n\n\n<li class=\"has-small-font-size\">Increased risk of galling<\/li>\n\n\n\n<li class=\"has-small-font-size\">Higher manufacturing costs<\/li>\n<\/ul>\n\n\n\n<p class=\"has-small-font-size wp-block-paragraph\">That\u2019s exactly why the vast majority of industrial products still use Grade 2 threads today.<br>Grade 2 isn\u2019t the standard because it is merely \u201cordinary.\u201d<br>It became the standard because, after balancing performance, manufacturability, serviceability, and cost, it proved to be the most practical solution.<\/p>\n\n\n\n<h3 class=\"wp-block-heading u-mb-ctrl u-mb-10\">Conclusion<\/h3>\n\n\n\n<p class=\"u-mb-ctrl u-mb-10 has-small-font-size wp-block-paragraph\">When it comes to bolt customization, the following upgrades are generally more effective than converting to Grade 1 threads:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"has-small-font-size\">Changing from 8.8-grade to 12.9-grade high-strength bolts<\/li>\n\n\n\n<li class=\"has-small-font-size\">Replacing steel bolts with titanium bolts<\/li>\n\n\n\n<li class=\"has-small-font-size\">Replacing corroded bolts with new ones<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"author":1,"featured_media":2584,"template":"","class_list":["post-17136","tips","type-tips","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/tips\/17136","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/tips"}],"about":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/types\/tips"}],"author":[{"embeddable":true,"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/users\/1"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/media\/2584"}],"wp:attachment":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/media?parent=17136"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}