![\"arm-1\"](\"http:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2015\/08\/arm-1.jpg\")
<\/a>It’s no secret that bolt-in a-arms for the nose of a purpose built drag car are readily available from plenty of sources. \u00a0Some of those pieces aren’t really dedicated drag race components. \u00a0Some are road-race inspired. \u00a0Some are simply replacement parts and some are just pretenders. \u00a0A select few of those pieces can actually pack plenty of sophistication, particularly for cars that see drag strip duty. \u00a0Case-in-point are the a-arms spread out in the photos in front of you. \u00a0These are top of the heap components manufactured by TRZ Motorsports.<\/p>\nWhy the need for aftermarket upper and lower control arms? \u00a0Simple. \u00a0The stock front suspension components bolted to the nose of your car as it rolled down the Detroit assembly line were never optimized for quarter mile use. \u00a0Vehicle manufacturers were typically conservative when it came to built-in caster (and actually super-conservative in the sixties).<\/p>\n
Let’s stop right here for a minute: What’s caster? \u00a0Caster is the backward or forward tilt of the spindle as you view it from the side of the wheel and tire. \u00a0When caster is positive, this means the spindle tilts backwards, which in turn, places weight behind the tire contact patch. \u00a0If the caster is negative, this means the top of the spindle is tilted forward, which in turn places weight in front of the tire contact patch. \u00a0Caster is expressed in degrees, and measures the amount the centerline of the spindle is tilted from true vertical. \u00a0\u00a0For the most part caster figures seldom go beyond -3\/4\u00b0 (negative), but in almost all drag race applications, positive caster is required.\u00a0 Why is that?\u00a0 Consider positive caster as a way to “self center” the steering.\u00a0 Ponder bicycles for a minute:\u00a0 A comfy long distance touring bike will have a fork that’s kicked out.\u00a0 This fork \u201ckickout\u201d provides a big chunk of positive caster. In turn, the bicycle experiences a significant amount of directional stability.\u00a0 Then take a look at a mountain bike. Here, the fork is much closer to vertical.\u00a0 The benefit of the mountain bike is that it can turn very quickly, however it definitely lacks directional stability. \u00a0The bottom line is, you can easily ride a touring bicycle with your hands off the handlebars.\u00a0 Try it with a mountain bike. It\u2019s not that easy (!!!).<\/p>\n
What about Camber?\u00a0 Camber is the tilt of the wheel at the top (tilting in or tilting out). Camber is expressed and measured in degrees, and looks at the tilt of the wheel from true vertical.\u00a0 If the wheel and tire package tilts out at the top, this means the camber is positive. If the top of the wheel and tire package tilts in, then the camber is negative.\u00a0 The real idea behind camber is to keep the tire planted squarely on the pavement.\u00a0 This creates maximum front tire grip. In theory, it sounds like zero degrees of camber is good but that isn’t always the case for race cars that were originally production line cars.\u00a0 Most production line cars require different camber figures (while at rest) so that good grip and tire wear is maintained as the car travels down the road.\u00a0 Typically, a car with a small amount of negative camber will exhibit better drag strip handling characteristics without killing the tire.<\/p>\n
Back to cars:\u00a0 A stock 1969 Camaro has a factory caster specification of \u00bd-degree + or \u2013 \u00bd-degree.\u00a0 In order to adjust the caster in a stock 1969 Camaro, you transfer shims front to rear or from rear to front. If you transfer one shim (1\/32-inch) from the rear bolt to the front will decrease positive caster by approximately \u00bd-degree.\u00a0 The opposite (transferring one shim from the front bolt to the rear bolt) will increase positive caster by approximately \u00bd-degree. That same 1969 Camaro has a camber specification of \u00bc-degree, + or \u2013 \u00bd-degree.\u00a0 To set camber, you have to add or subtract an equal number of shims from the front and the rear bolts on the a-arm cross shaft.\u00a0 One shim (again, 1\/32-inch) at each location will change the camber by approximately 1\/5-degree. Adding a shim at each end will decrease<\/u> positive camber.<\/p>\n
So far so good, but camber and caster are usually set together.\u00a0\u00a0 What that means is you\u2019ll probably physically run out of room to properly adjust the caster and camber on a the car with stock a-arms.\u00a0 This becomes very apparent when you try to get a reasonable (for drag racing) caster number in a first gen Camaro.\u00a0 To get something like five or six (or even seven) degrees of caster is difficult, if not impossible.\u00a0 That\u2019s one big reason why the TRZ Motorsports A-Arm package is a serious problem solver for drag race applications.\u00a0 When TRZ engineered the control arms, they built in 5-7-degrees of positive caster. TRZ points out:\u00a0 \u201cCaster varies on cars that have different ride heights. \u00a0If the rear of the car is higher than the front, it then has less caster. \u00a0In some cases people can only get 5 degrees or so due to variances in the frames, prior accident damage, front frame damage, or the rear of the car sitting too high.\u201d\u00a0 It all means it\u2019s possible to come up with way more positive caster than stock. Now, with a lot of caster your car won\u2019t like backing up so much, but it sure will track well at speed.\u00a0 Besides, you don\u2019t have to parallel-park a racecar very often!<\/p>\n
Next issue we\u2019ll dig deeper into the \u201cA-Team\u201d.\u00a0 There\u2019s much more here than you might expect.\u00a0 Watch for it.<\/p>\n
Take a closer look at TRZ Motorsports a-arms in the first part of this series.<\/p>\n<\/div>","protected":false},"author":20,"featured_media":17601,"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":[11,9],"tags":[3272,4800,461,706,321],"class_list":["post-17599","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-how-tos","category-tech-tips","tag-control-arms","tag-how-tos","tag-tech-tips-2","tag-trz-motorsports","tag-wayne-scraba"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2015\/08\/arm-1.jpg","jetpack_shortlink":"https:\/\/wp.me\/p42YSK-4zR","jetpack_sharing_enabled":true,"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/17599","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=17599"}],"version-history":[{"count":1,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/17599\/revisions"}],"predecessor-version":[{"id":17607,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/17599\/revisions\/17607"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media\/17601"}],"wp:attachment":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media?parent=17599"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/categories?post=17599"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/tags?post=17599"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/p>\n<\/a><\/a><\/p>\n<\/a><\/a>