{"id":33375,"date":"2016-12-06T11:42:41","date_gmt":"2016-12-06T19:42:41","guid":{"rendered":"http:\/\/www.racingjunk.com\/news\/?p=33375"},"modified":"2016-12-06T16:17:02","modified_gmt":"2016-12-07T00:17:02","slug":"how-to-select-gear-ratio-combos-for-better-performance-2","status":"publish","type":"post","link":"https:\/\/www.racingjunk.com\/news\/how-to-select-gear-ratio-combos-for-better-performance-2\/","title":{"rendered":"How to Select Gear Ratio Combos for Better Performance"},"content":{"rendered":"<p class=\"jetpack-slideshow-noscript robots-nocontent\">This slideshow requires JavaScript.<\/p><div id=\"gallery-33375-1-slideshow\" class=\"jetpack-slideshow-window jetpack-slideshow jetpack-slideshow-black\" data-trans=\"fade\" data-autostart=\"1\" data-gallery=\"[{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-1.jpg&quot;,&quot;id&quot;:&quot;33361&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;Click Here to Begin Slideshow\\n\\nA long time ago, there wasn\\u2019t much to think about when it came to gear ratios. Bigger was better. Out back, you had to pack (at least) a set of 4:11\\u2019s to be somebody. The reality was, you didn\\u2019t have much choice either; for example, if you were a GM guy all you could get inside a close ratio Muncie was a 2.20:1 first gear set. GM Powerglides offered a bit of choice as they came in either a 1.76:1 or a 1.82:1 low gear format. Choices weren\\u2019t all that different in the Ford or Mopar camps either, although they had better (deeper) first gear ratios in their transmissions. It\\u2019s true you could mix and match certain transmissions with different engines, but that usually meant a mix of adapters, release bearings and other not-so-standard hardware.\\n\\nThat was then. Today things are very different. From a mechanical perspective, ratio choices for both the rear axle and the gearbox are extensive. Equally important is the fact that modern tuning, particularly with electronically fuel injected engine combinations, takes the engine torque curve, the transmission gear ratios, torque converter slippage (and indirectly, the torque converter stall speed), rear axle ratio and tire roll out (diameter) dimensions into consideration as a total package. That\\u2019s not the end of it either; overdrive transmissions are commonplace. Tires are available in a zillion different combinations. When all of the factors are tallied, it\\u2019s easy to see the combinations can have a decisive effect upon how your car runs.\\n\\nAs you can well imagine, there\\u2019s a veritable truckload of recipes. The mix can include the engine torque curve, the transmission gear ratios (along with the torque converter stall speed), the rear axle ratio and the overall diameter of the rear tires. Over the course of this short series, we\\u0026#8217;ll take several hypothetical and real, common combinations and show the effects of the variables. We\\u2019ll show you how these variables intertwine and how you can crunch the numbers to work out the right ratios for your modified car. \\n\\nFirst, look closely at the rolling stock fitted to a modern high performance car. It will seldom be 26.5 inches in height. If you spin back the clock, tires with diameters two, three and even four inches bigger were the norm. Nostalgia hot rods tend to be great examples \\u2013 they often roll on rear rubber that\\u2019s 30-inches tall or greater in height. Today, a street-strip car might wear set of P275-60 rear tires. They\\u2019re typically 28 inches tall. Changes in tire height from 26 to 28 to 30 inches aren\\u2019t minor changes in the overall combination. They can have a considerable effect when figuring rear axle ratio. We\\u2019ll dig into this deeper in the second part of our series.\\n\\nBut before we get there, one of the first points to consider in the overall combination is the RPM of the engine at approximately 60 miles per hour. Just how fast is that engine under your hood turning? Not long ago, cars came with very short axle ratios (high 2-series ring and pinions were common). Coupled with 1:1 high gear (a typical pre-overdrive automatic or manual trans), the engine could be turning well below 2,000 RPM. Factor in an overdrive, as found on most later production vehicles and plenty of street rods, and the engine will be running just off idle. As you imagine, when you whack the throttle pedal at 60 MPH in an application such as that (2-series ring and pinion, overdrive automatic), the engine response will prove lackluster \\u2013 particularly if the engine has been modified \\u0026#8211; we understand that an automatic will drop down a gear when this happens, or with a stick, you can drop down a gear or two, but that\\u0026#8217;s not the point. Worse yet, the engine speed could easily be well beneath the torque curve, which often ends up translating as worse-than-expected fuel economy numbers.\\n\\nOn the flipside of the coin is the combination that, for example, turns 3,500 RPM or more at 60 miles per hour. Performance is, to say the least, lively with a combination such as this. Sure you might live with it for a once-a-month hop to the local drag strip, but using such a car with regularity can get old real fast, and given today\\u2019s gasoline prices, it can get real expensive too. \\n\\nWhen it comes to selecting the right gear ratio for your hot rod or street machine, the real place to begin is the engine combination. For the sake of comparison, we decided to include a very lightly modified rebuilt Ford 302, a GM Performance Parts ZZ4 crate engine and a slightly hopped up 376 cubic inch LS small block. While these combinations might not exactly match the hot rod you have in the garage, the information proves thought-provoking. By the way, these aren\\u2019t real engines, simply hypothetical combinations. The torque figures for each look like this:\\n\\n\\nTorque Chart\\n\\n                                    302                            ZZ4                             LS                            \\n\\nRPM                 Torque \\u0026#8211; Lb-Ft         Torque \\u0026#8211; Lb-Ft         Torque Lb-Ft\\n\\n________________________________________________________________\\n\\n\\n2000                           266                             352                             435                            \\n\\n2500                           270                             365                             465                \\n\\n3000                           295                             402                             520                \\n\\n3500                           314                             405                             545                \\n\\n4000                           315                             400                             555                \\n\\n4500                           307                             390                             560                \\n\\n5000                           290                             355                             540                \\n\\n5250                           269                             338                             480                               \\n\\n                    \\n\\nIn the example above, we have three very different engine combinations along with three very different torque curves (no surprise). The torque peaks vary for the displacement and it makes sense that each of these engine combinations will really work better with a specific transmission and rear axle ratio package. The reality is, the overall driveline gearing package should be designed to match the torque characteristics of the engine. If it isn\\u2019t you won\\u2019t have much fun driving the car.\\n\\nIt\\u2019s clear the large displacement LS engine listed above isn\\u2019t lacking when it comes to torque. Note the figures: It produces almost 170 more torque (Lbs-Ft) at 2,000 RPM than the little 302 produces and just off idle; the largest displacement engine produces more torque than the ZZ4 does at its peak. The ZZ4 is no slug either, but you\\u2019ll note the torque curve isn\\u2019t nearly as \\u201cfat\\u201d as the hypothetical LS. The reality is the LS combination can easily get by with less gear (transmission and\\\/or rear axle) than the little 302. There\\u2019s a downside, however: If you use too much gear (a high numerical gear set) the result will usually end up as fried tires with the bigger engine combination. This is something you can\\u0026#8217;t take lightly when choosing gear ratios.\\n\\nDecades ago, one of this writer\\u2019s magazine assignments was to assemble a dozen winning tips from a dozen winning racers. Bill \\u0026#8220;Grumpy\\u0026#8221; Jenkins was one of the first racers interviewed. I held Jenkins in great esteem at the time \\u2013 still do \\u0026#8212; and even though he\\u2019s no longer with us, his depth of knowledge is still worth sharing. Although his exact words escape me, Bill noted that far too many drag racers over-geared their combinations (buzzing them as they went through the lights). He felt many racers failed to take engine torque and the actual power band into consideration. Jenkins went on to point out that in many cases, a little bit less rear gear could actually make a given car quicker, faster, more consistent and, ultimately, more reliable. Although Jenkins\\u2019 knowledge was geared toward drag racing, it still applies equally well to street driven hot rods and street-strip cars. Bottom line? Taming a rear axle ratio might actually make your car a better (and quicker) high performance machine.\\n\\nSo how do you figure it all out? There are plenty of online calculators out there that crunch the numbers for you, but in our next issue, we\\u2019ll lay out a few basic calculations you can use at home. They\\u2019re not complicated and they can put you right into the performance zone for your specific gear ratio package. Watch for it.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-2.jpg&quot;,&quot;id&quot;:&quot;33362&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 1&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;The characteristics of the engine mounted in your engine compartment definitely have an effect upon gear ratio selection.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-3.jpg&quot;,&quot;id&quot;:&quot;33363&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 2&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;A honking blown first generation Hemi or a monster cubic inch shotgun Ford is going to have a torque curve far different than something like a relatively mild LS crate motor.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-4.jpg&quot;,&quot;id&quot;:&quot;33364&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 3&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;Keep the features of your engine in mind when considering different gear ratios.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-5.jpg&quot;,&quot;id&quot;:&quot;33365&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 4&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;Another major factor in the selection of gears is the back rubber. Big tires such as the Hoosiers on this \\u201832 are extremely tall.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-6.jpg&quot;,&quot;id&quot;:&quot;33366&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 5&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;While the drag radials on the Buick in this photo aren\\u2019t as big as the Hoosiers, they\\u2019re still plenty big.&quot;,&quot;itemprop&quot;:&quot;image&quot;},{&quot;src&quot;:&quot;https:\\\/\\\/www.racingjunk.com\\\/news\\\/wp-content\\\/uploads\\\/2016\\\/12\\\/Gear-7.jpg&quot;,&quot;id&quot;:&quot;33367&quot;,&quot;title&quot;:&quot;How to Select Gear Ratio Combos for Better Performance 6&quot;,&quot;alt&quot;:&quot;How to Select Gear Ratio Combos for Better Performance&quot;,&quot;caption&quot;:&quot;Compare these large tires to the super short rolling stock found on the \\u201940 coupe in this photo. It\\u2019s not hard to find a diameter range of six, seven or more inches in street tires.&quot;,&quot;itemprop&quot;:&quot;image&quot;}]\" itemscope itemtype=\"https:\/\/schema.org\/ImageGallery\"><\/div>\n","protected":false},"excerpt":{"rendered":"<div class=\"mh-excerpt\"><p>A long time ago, there wasn\u2019t much to think about when it came to gear ratios. That was then. Today things are very different.<\/p>\n<\/div>","protected":false},"author":20,"featured_media":33361,"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":[11,3470,4879,9,5012],"tags":[1623,4800,41,4888,461,321],"class_list":["post-33375","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-how-tos","category-news","category-slideshow","category-tech-tips","category-transmission-clutch","tag-gear-ratio","tag-how-tos","tag-news","tag-slideshow","tag-tech-tips-2","tag-wayne-scraba"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.racingjunk.com\/news\/wp-content\/uploads\/2016\/12\/Gear-1.jpg","jetpack_shortlink":"https:\/\/wp.me\/p42YSK-8Gj","jetpack_sharing_enabled":true,"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/33375","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=33375"}],"version-history":[{"count":1,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/33375\/revisions"}],"predecessor-version":[{"id":33480,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/posts\/33375\/revisions\/33480"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media\/33361"}],"wp:attachment":[{"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/media?parent=33375"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/categories?post=33375"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.racingjunk.com\/news\/wp-json\/wp\/v2\/tags?post=33375"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}