{"id":7798,"date":"2014-09-04T09:53:30","date_gmt":"2014-09-04T16:53:30","guid":{"rendered":"http:\/\/www.racingjunk.com\/news\/?p=7798"},"modified":"2016-11-30T12:00:56","modified_gmt":"2016-11-30T20:00:56","slug":"axle-essentials-for-racing-and-performance-part-1","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/axle-essentials-for-racing-and-performance-part-1\/","title":{"rendered":"Axle Essentials for Racing and Performance, Part 1"},"content":{"rendered":"

\"Axle<\/a><\/p>\n

Axles?\u00a0 What\u2019s the big deal? Once you see a racecar that just pitched a wheel (most often with a chunk of the axle attached), you get a far better understanding of why axles are critical.\u00a0 It\u2019s also the reason why most race sanctioning bodies have rules that lay out what you can and cannot have when it comes to axles (case in point:\u00a0 some sort of positive axle retention device, which translates into no c-clips).<\/p>\n

\"This<\/a>
This is what a set of quality axles look like once forged, machined and heat treated.<\/figcaption><\/figure>\n

But let\u2019s start from the beginning.\u00a0 Original equipment automotive axles are typically manufactured from 1055 or 1541 steel. Typically, they\u2019re on the borderline between a medium and a high carbon steel with a relatively large manganese content. 1055 has a carbon content between 0.50%-0.60% while 1541 has between 0.36-0.44%. The cabon content allows the shaft to be induction hardened. It\u2019s also easy to work with.\u00a0 These original equipment axles are induction hardened up to the bearing mount surface (next to the flange — induction hardening is used to selectively harden areas of a part or assembly without affecting the properties of entire component).<\/p>\n

\"Two<\/a>
Two different types of heat treat are commonly used when it comes to axles.<\/figcaption><\/figure>\n

With induction hardening, the axle shaft passes through an electromagnetic coil. Eddy currents are generated within the metal, which in turn heats the shaft.\u00a0 The shaft is then quenched.\u00a0 This hardening process leaves the shaft with a surface hardness of 55-58 Rockwell, penetrating to a depth of approximately 0.150-.300 inch.\u00a0 The core of the axle remains relatively soft, but the surface is very hard \u2013 almost brittle.\u00a0\u00a0 So far so good, but this type of axle, with a soft flange is better suited for folks smacking curbs than it is to handle the shock loads of something like a drag race car.<\/p>\n

\"This<\/a>
This Mark Williams photo shows the austempering process they use on their Hi-Torque axles.<\/figcaption><\/figure>\n

But curbs and potholes aren\u2019t the biggest concern for a racecar (or even a street-strip machine). Factors for these applications include determining how much of a load will be placed on the axles at launch, the overall weight of the various drivetrain pieces (more on this down the road) and of course the size of your budget.\u00a0 <\/b><\/p>\n

Calculating the amount of torque applied to an axle is easy:\u00a0 Take the engine torque output and multiply it by both the transmission first gear and rear end gear ratios.\u00a0 If it\u2019s an automatic, the multiplication factor from the torque converter should also be added in the mix.\u00a0 In the sum total, it\u2019s really not that unusual to see figures of more than 10,000 foot lbs. of torque transmitted to the axles.\u00a0 That\u2019s a bunch.<\/b><\/p>\n

With these kind of loads there\u2019s more to it than simply the tensile strength of the material. The ductility of the axle shaft itself plays an important role: The torsional load presented to the axle is so large that it must be able to twist and rebound like a torsion bar instead of being too stiff and ultimately snapping.<\/b><\/p>\n

Rewind a couple of paragraphs.\u00a0 Recall that induction hardening used on OEM axles?\u00a0 While it might be great to combat impacts from curbs and potholes, something else is needed for racecar and super high performance pieces.\u00a0 We turned to Mark Williams Enterprises for information on axle performance and especially ductility:<\/p>\n

To achieve the kind of ductility necessary for racing purposes, Mark Williams Enterprises exclusively employs an Austempering process on its Nickel-Chromium-Molybdenum alloy Hi-Torque axles. This heat-treating process involves submerging the axle in a molten solution at over 1500 degrees (F) and then quenching the components in a molten brine solution. This results in a material structure known as Bainite \u2014 it proves far superior to the Martinsite structure that comes with the ordinary heat treating and oil-quench process that are commonly employed (that results in a more brittle axle). Other important benefits of Austempering include the axles having higher impact and fatigue strengths, have a resistance to hydrogen embrittlement, and having a more uniform hardness plus increased wear resistance.\u00a0 In the end, the choice of materials coupled with the Austempering process provides an axle with an ultimate tensile strength of 225,000-253,000 psi along with exceptional ductility (the ability to change shape or form without breaking). The shaft surface hardness is approximately 50 Rockwell, which proves to be far less brittle than an induction-hardened carbon steel axle.<\/p>\n

\"This<\/a>
This is the second type of hardening process used with axles. It\u2019s called Induction Hardening<\/figcaption><\/figure>\n

OK.\u00a0 If all of that is necessary to build good axles, why do you see \u201cAlloy Axles\u201d advertised so cheaply?\u00a0 The reality is, those components are actually produced by an OEM axle forging company. The main business of that company is to manufacture axles for the heavy truck and construction industries.\u00a0 And yes, the material used is a carbon steel, common to original equipment axles axles.\u00a0\u00a0 In this case, the manufacturer produces an axle blank.\u00a0 The company selling those inexpensive alloy axles cuts the axle to length and then splines it. These axles are made from the same material as stock axles and receive the same heat treatment. The only real difference is that they are available in shorter lengths and with different splines. Now you know why they\u2019re cheap. And you get what you pay for.<\/p>\n

Next week, we’ll talk about splines.<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Axles? What\u2019s the big deal? Once you see a racecar that just pitched a wheel (most often with a chunk of the axle attached), you get a far better understanding of why axles are critical. Learn more about them in the first of this four part series.<\/p>\n<\/div>","protected":false},"author":20,"featured_media":7801,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5011,3465,11,9],"tags":[1280,1277,1314,4800,1279,461,1278],"class_list":["post-7798","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-chassis-suspension","category-drag-racing","category-how-tos","category-tech-tips","tag-aftermarket-parts","tag-axles","tag-axles-101","tag-how-tos","tag-induction-hardening","tag-tech-tips-2","tag-wayne-scrabe"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2014\/09\/Axle-1Feature.jpg","jetpack_shortlink":"https:\/\/wp.me\/p42YSK-21M","jetpack_sharing_enabled":true,"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/7798","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/comments?post=7798"}],"version-history":[{"count":7,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/7798\/revisions"}],"predecessor-version":[{"id":33227,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/7798\/revisions\/33227"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media\/7801"}],"wp:attachment":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media?parent=7798"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/categories?post=7798"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/tags?post=7798"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}