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4 Reasons The Ford 9-Inch Is The Ultimate Performance Differential
The iconic Ford 9-inch has been the go-to diff for hot-rodders since day one. The brilliance of the unit is its ability to hold power, its quickness in changing gears, its vast range of available gear ratios, and the ease in which it can be setup. Shop our Ford 9-inch differential products here. The Ford 9-inch was produced from 1957 to 1986 and came standard in a wide variety of Blue Oval cars and trucks. As one would expect, the aftermarket has kept the 9-inch alive, offering its own versions of the long-standing design. Spotting A Ford 9-Inch The Ford 9-inch is a dropout-style differential. Looking at the pumpkin, or center section, you’ll notice the gear set is accessed through the center cover on the pinion side of the axle where the driveshaft connects, not from the back over like a more common carrier-type of rear end. Early, pre-1966 9-inchers have a round housing where later versions of the 9-inch had a hump integrated into the housing. All 9-inches are not created equal. Ford produced diffs with many different widths ranging from 57 ¼” to 69 ¼” measured from the outer flanges on each axle tube. While on the topic of spotting Ford 9-inchers, it’s worth mentioning there is a Ford 9 3/8” diff. None of the parts interchange with the 9-inch. This pretender can be identified externally by the top horizontal rib curving down at the end… which is kind of frowning, like people do when they realize it’s not a ‘real’ 9-inch. Holding The Power “In real world applications OE third members were produced in many different configurations and materials,” says Gus Pyeatt, RANDYS Worldwide tech support specialist. “The majority were just a common grey iron with minimal ribbing, these start to see fairly significant deflection in a light car around the 300-horsepower mark, less in heavy cars and trucks. There were some factory HD or “N” nodular iron cases that had much more pronounced webbing. These will usually hold about 400 horses in a street car application before seeing significant deflection. Aftermarket cases enjoy a huge jump in rigidity even when reducing weight by going to aluminum. The power handling in these custom cases more than triples to the 1,200 range. Add in big bearing cases with 10-bolt pinion supports and thru-bolted caps, and you see many 9-inchers that hardly notice 2,000 horses being thrown at them.” Other Ford 9-Inch Performance Advantages Beyond corralling horses, the Ford 9-inch’s performance advantage includes its ease of serviceability, and for early hot-rodders, its versatility. These founding father enthusiasts had the ability to drive to the track with highway gears, then swap in another third member with deep gears and a spool, race or do their shenanigans, then swap back at the end of the day. According to Gus hot-rodders also liked how lightweight the stamped steel “banjo” housing was and its ease in adapting to other applications. “Sheetmetal is much easier to weld on and otherwise alter than cast iron. As time went on, ratio selection exploded, allowing the circle track racers to fine tune gearing from track to track all but making the old “quick change” rears obsolete.” The 9-inch’s design benefits performance from a ‘bigger is better’ standpoint as well. Ford 9-inch diffs feature larger diameter ring gears which creates additional distance between the centerline of the ring gear and the centerline of the pinion gear, known as hypoid distance. This relationship impacts performance. “The key here is hypoid offset,” says Gus, “The vertical offset from the axle centerline. It’s not something that is adjustable, it’s engineered into the gear set and housing. It’s a balancing act, the more the offset, the larger your tooth contact on the gears, which has the effect of strengthening the rear end assembly. The offset also changes how the pinion shaft is loaded, with 0 offset the pinion shaft sees the load at a 90-degree angle, as the offset is increased the angle is reduced, and becomes more in line with the pinion shaft, which allows for a shorter pinion shaft to handle the leverage.” The Ford 9-inch pinion gear features a stub on the gear end. The stub is supported within the housing (red arrow) via a pilot bearing. “Ford went so far as to further improve that side load issue by adding a third bearing which splits the load between the two bearings rather than using the single bearing as a fulcrum. The gear end of the pinion features a stub that provides additional support to the pinion via that third bearing, along with splitting the load this setup also benefits performance by limiting gear deflection under high-torque loads.” Shop our Ford 9-inch ring and pinion gear sets here. It should be noted that there is a slight drop in efficiency with hypoid offset but it’s nominal. Nevertheless, there are some on the interwebs that characterize this inefficiency as blasphemy and liken the 9-inch to a boat anchor. “We are talking 1% to 2% difference,” says Gus. “For some users that change will be a minimal concern, for a competitive team it may be a deal breaker. But it is enough of a concern that good old corporate average fuel economy helped force the 9-inch out of production.” The Ultimate Gear Swapper The Ford 9-inch’s removeable front gear case makes swapping gears incredibly easy. Simply unbolt the gear case, lift it out, and move it to the workbench. This way all the assembly and setup can be done more comfortably on the workbench rather than under the vehicle as in most carrier-type diffs. When it comes to gear ratios, the sky is the limit. There are more available gear ratios for the Ford 9-inch than most any other differential. Offerings ranging from the low 3s to mid 6s, in increments that measure down to tenths of a ratio make it easy for the Ford 9-inch owner to swap gears and tune their traction with unrivaled precision. Troublesome Troubleshooting It’s not all roses and unicorns with the Ford 9-inch. Troubleshooting can be difficult in a Ford 9-inch because you have to commit to removing the entire carrier where in a typical GM 10- or 12-bolt carrier diff you can simply pop the cover off and glean the inner workings for any worn or broken parts. The caveat here is some aftermarket 9-inch diffs are outfitted with rear ‘inspection’ covers for just this scenario. Easy Gear Pattern Adjustments In a Ford 9-inch the pinion gear and accompanying small parts are installed in their own separate, detachable sub-housing, often referred to as a cartridge or pinion support. This arrangement promotes easy adjustments to gear set alignment. Here we see the retaining bolt being loosened to remove the adjuster lock, a Yukon side adjuster tool, and the adjuster being manipulated. Further, the 9-inch has screw-type adjusters rather than shims, which makes dialing in the gear set all the more easier because you don’t have to worry about preloading the shims to evaluate gear tooth alignment. Simply tighten or loosen the adjuster nuts on both sides of the housing to move the gear until proper alignment is achieved…. No shim hammering, no headaches. Time Is On Your Side Although Ford ceased production in ‘86, the aftermarket has not missed a beat, developing parts for the diff that take full advantage of all the advancements in technology, materials, and manufacturing through the ensuing decades. Some of these revelations include aftermarket cases made from tough nodular iron and billet aluminum not the gray iron used in the originals. The aftermarket Ford 9-inch differential at left consists of a Yukon nodular iron case, Yukon aluminum pinion support, and a Yukon yoke. The aluminum pinion support allows the use of a larger-than-stock bearing, further enhancing the unit’s durability. Beyond the diff, the evolution of axle technology will also impact the strength and longevity of the diff. The use of chromoly and other materials and the development of custom axles with more splines than stock offerings all make for a more robust differential. Even the ring and pinion gears themselves have not escaped as larger gear sets are being made from exotic high alloy steels. Enthusiast drivers are the big winners. They get a diff that can hold more power and live longer than the originals could ever dream of. The possibilities are endless and we appreciate all the Ford 9-inch brings to the table. In fact, RANDYS Worldwide and its Yukon Gear & Axle brand offer tons of Ford 9-inch parts so you can properly build and gear your diff to match your power levels and driving habits. Ready to step up to the big time? Let us help. Shop Ford 9-Inch Gear Sets
How It Works: Dropout Vs. Carrier-Type Differentials
A pumpkin is a pumpkin, right? We’re talking about differential housings not jack-o’-lanterns; and hold your horses all are not created equal in the eyes of the drivetrain gods. While diff housings all do the same basic thing: house the gears that make forward motion possible, there are two different designs at work here. Dropout Differentials Dropout differentials, also known as third members, can be readily identified by their removable front center section. The ring and pinion gear set in a dropout diff is contained within a carrier assembly that can be removed or dropped out for easy access. The iconic Ford 9-inch is a dropout or third member type of differential and GM, Toyota, and Chrysler also offer dropout diffs. The ribbed housing is a quick giveaway that this is a Ford 9-inch. Along with the OE Ford 9-inch, there are tons of custom aftermarket Ford 9-inch configurations. The General has dropouts but many of them date back to the 1950s and are not relevant today. Toyota dropout-style diffs consist of the 7.5” rear, 8” rear, 8” high pinion, 8” clamshell, 7.5”, 8.5”, T100 IFS, and numerous 9”, 9.5”, and 10” offerings. In the Mopar world dropout differentials are called banjo-style diffs because someone thought the assembly, when pictured with an axle shaft, had the look of the infamous stringed musical instrument. The Chrysler 8.75” is the automaker’s most popular dropout-style diff. Of course, Dana manufactures a number of dropout style diffs that appear in vehicles across numerous brands. In some circles a front-loading dropout-type diff is known as a pig-style diff. While on the subject of slang, our friends across the pond call the ring gear a “crown wheel” … hey, as long as we’re on the same page it’s all good. Perhaps the main inherent advantage of a dropout diff is easy gear swaps. The gear swap advantage boils down to where you do the work. Since the gear case center section can be unbolted and removed, all the ring and pinion gear installation and tedious setup can be done away from the vehicle on a workbench. It’s more comfortable and access to, and applying leverage on, the key components is much easier. Carrier Differentials Carrier differentials have a cover on the backside of the pumpkin that is unbolted to gain access to the ring and pinion gears and other internal workings of the diff. GM’s 10-bolt and 12-bolt differentials are common examples of carrier-style diffs, which may be referred to as Salisbury differentials by those who speak the Queen’s English. The fact that the gears are visible on the backside of the housing is a telltale sign this is a carrier-type differential. Carrier-type differentials are more popular and they have some strengths when compared to a dropout diff. Troubleshooting is one. Looking for broken or worn parts in a carrier diff is as easy as removing the back cover where in a dropout you have to commit to a full gear case removal to see what’s going on. It should be noted that some custom aftermarket dropout diffs have rear inspection covers to address this concern. There is a less common concern for carrier diff drivers who wheel on the weekends; the diff cover. Traversing craggy terrain can result in the stock diff cover being peeled back like a can of sardines. A protruding rock or tree stump can also spell doom by way of impact damage. The answer: Yukon Hardcore Performance Diff Covers. They look great and are constructed from thick-walled high strength nodular steel to protect lockers, gears, and axles from extreme impacts as well as deflection caused by flex in the housing. Hardcore Performance Diff Covers come with a durable powder coat finish, magnetic drain plug, quality gasket, and high-strength steel fasteners for easy bolt-on installation. Knowing what dropout and carrier-type differentials are and a general idea how they work will help you make more informed installation decisions as you have the knowledge and vocabulary to talk straight with your mechanic. Shop Re-Gear Kits
YA WU-07-08
Introducing Yukon Stage 2 Re-Gear Kits For Jeeps
Yukon Gear & Axle® Stage 2 Re-Gear Kits consists of front and rear Yukon ring and pinion gear sets, installation kits, and front and rear Yukon Hardcore Diff Covers. The kits can be ordered in gear ratios ranging from 3.73, 4.11, 4.56, 4.88, 5.13, and 5.38. They are available in a variety of Rubicon and non-Rubicon applications for JK, JL, and JT Jeep Wranglers and Gladiators. A big benefit of these kits is how they allow the savvy Jeep owner to move to a more aggressive gear ratio if they choose. Whether you’re optimizing the performance of your current setup or dialing in a big-tire upgrade, Yukon has all the bases covered. The kits are application-matched so you get all the right small parts needed for a complete installation with one easy-to-order part number. Stay tuned as Yukon will be expanding this kit program to include versions that bundle additional components for enthusiasts who want even more of that go-anywhere capability when the trail calls. Shop Yukon Gear & Axle Staged Re-Gear Kit For Jeeps Yukon Gear & Axle Stage 2 Re-Gear Kit Delivers Yukon front and rear ring and pinion gear sets Front and rear installation kits Front and rear Yukon Hardcore Diff Covers