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How It Works: Positraction Limited Slip Differentials
Positraction or Limited Slip Differential Limited Slip Differentials (LSD) significantly increase the traction and performance of Jeeps, trucks, 4×4s, and RWD vehicles on the street, at the strip, or on the trail. Positraction is what General Motors called its limited slip differential, the term has come to refer to LSDs in general. How Do Limited Slip Differentials Work? An LSD’s main job is directing torque where it’s needed. When you’re driving in a normal manner a positraction limited slip differential is pre-loaded and provides equal traction to both wheels. Mashing the throttle, taking a tight corner aggressively, or working through loose gravel trails will result in the limited slip differential limiting wheel spin across the drive axle by permitting the axle shafts to spin at different speeds while continuously trying to balance the application of torque between the two axles. This results in transferring more power to the wheel with the best traction which enhances the grip, control, and the predictability of the vehicle. Are There Different Kinds of Limited Slip Differentials? Yes. In their static state, when traveling in a straight line where wheel speeds are identical on both sides, all limited slip differentials provide equal traction to both tires. The difference between LSD types is how each unit applies torque when additional traction is needed. Clutch-Type Limited Slip Differential In regular circumstances a clutch-typeunit, like the Yukon Dura Grip, uses an array of springs to apply pressure to the side gears which puts pressure on the clutch packs in the outer part of the carrier. Both axles get equal pressure and both tires get equal traction. When a tire starts slipping, the clutch packs are engaged with differing resistance. The clutches compensate to maximize traction between the tires, transferring more torque to the tire that has the best grip while reducing torque transfer to the tire that has less grip. All Dura Grip units are four-spring designs built with a high-strength nodular iron case, forged 4320 chromoly spider gears, and high-quality composite clutches. The Dura Grip positraction limited slip differential is engineered for long life and is completely rebuildable. The clutches can be replaced to bring the unit back to its original performance level, or different clutches and spring rates can be used to fine tune the Dura Grip’s performance to better match the style of driving/racing you are doing. The Yukon Dura Grip is transparent in its traction enhancement, coming online only when the edge of adhesion is reached and slippage occurs. This makes it ideal for daily drivers that will be driven hard on the street and see extended action on the trail or at the track. Yukon Dura Grip Specs Four-Spring Clutch-Type LSD High-Quality Composite Clutches Tough Nodular Iron Case Forged 4320 Chromoly Gears Fits All Gear Ratios Choose from Four Levels of Spring Pressure When Rebuilding Each Unit is Quality Tested and Assembled in the U.S.A. Recommended Gear Oil: Non-Synthetic 80W-90 GL-5 1-Year Warranty Against Manufacturing Defects Gear-Type Limited Slip Differential A gear-type LSD, like the Spartan Helical LSD from USA Standard Gear, have no frictional surfaces to initiate torque transfer. It uses floating helical-cut worm gears that operate in pockets and mesh together. Under normal driving conditions this type of LSD acts like an open diff. When acceleration or wheel slippage occurs, axial and radial thrust is applied to the helical gear pinions in their pockets. Under these loads, more torque is transferred to the tire with the best traction, in a progressive manner, as torque is withheld from the tire that is slipping. The Spartan Helical LSD provides smooth engagement, quiet operation, and requires no maintenance. The unit’s 10-pinion design has a strength advantage over an equivalently sized 6-pinion or 8-pinion unit because it has more points of contact and a greater surface contact area to deliver optimal load distribution. This LSD is built tough. The Spartan Helical LSD is a fully assembled unit featuring a forged 8620 grade steel case and stout 8620 alloy internals for superior durability. Spartan Helical LSD Specs Fits Dana 30 Front Differentials 27 Spline, 3.73-And-Up Ratio Enhanced Off-Road Grip, No Compromise of On-Road Drivability Maintenance Free, No Clutches to Rebuild Low Noise, Smooth Engagement, Linear Traction Forged 8620 Grade Steel Case, 8620 Alloy Internals for Superior Durability Recommended Gear Oil: Non-Synthetic 80W-90 GL-5 Use of Friction Modifiers Not Recommended Assembled in the U.S.A. 1-Year Warranty Against Manufacturing Defects Because they give your ride that extra bit of bite, limited slip differentials are ideal for daily drivers that will be driven hard on the street and see extended action on the trail or at the track. Whether you’re facing mud, loose gravel, or steep inclines on the trail or slippery snow or rain on the road, the Spartan Helical LSD will ensure you have unrivalled traction and supreme confidence in your vehicle. Shop Limited Slip Differentials Or Call Now 866-631-0196 Spartan Helical LSD Yukon Dura Grip
How It Works: Pinion Bearing Preload
Pinion bearing preload is a critical step in the differential overhaul process because if you get too heavy handed you have to backtrack and start over. Further, getting this procedure right sets the stage for each following step of reassembly. It should be noted from the get-go that there is a difference between the minimum torque value for the pinion nut and the pinion bearing preload. The process starts by securing the nut to the pre-described minimum torque, then measuring preload and tightening in small increments as required until the target preload is attained. Pinion Installation Basics Starting with a bare pumpkin, oil the front and rear pinion bearing surfaces in the diff housing then drive the pinion races into the housing using a pinion bearing race driver until they are fully seated. Clean and apply high quality silicone to the races. TIP Treat pinion bearings and bearing races as a mated pair? If you have to change out a pinion bearing remember to install new races as well. Install pre-oiled front pinion bearing and pinion seal. Follow that up with installing the pinion gear and crush sleeve. Next, install pinion the yolk onto pinion splines making sure not to damage the pinion seal when tapping the yoke into place. Finally, apply oil to the pinion nut washer or thrust surface of the pinion itself, put some thread locking compound on pinion threads or threads of the pinion nut, and hand start the nut. Torque Value Versus Preload Tighten the nut until you can feel resistance when turning the yoke back and forth, check torque load. Typical starting points are 55 lb-ft for 3/8-inch bolts/nuts, 75 lb-in for 7/16-inch bolt/nuts, and 125 lb-in for 1/2-inch nuts/bolts. TIP Tap the end of the pinion gear with a punch to ensure the races are fully seated, shake it to evaluate for excessive play. Once you’ve confirmed the nut is properly torqued check for preload. Using a dial-style inch-pound torque wrench spin the nut/pinion to get a running measurement of how much torque it takes to spin the pinion. We’re talking about the running friction or rotating friction of the assembly, not necessarily brake torque. Check, tighten, and check the preload as you go and continue to tighten until you reach the desired/required pinion bearing preload for new bearings as indicated on the accompanying chart. Sneak up on the proper measurement, if you over-torque the pinion nut and get too much preload you will need to replace the crush sleeve and start again. Preload Importance As mentioned earlier, this is the first step of the journey, getting off on the right foot is all the more important. Stability is the end goal of proper preload. Getting this step right prevents the ring and pinion gear from moving in a vertical, horizontal, or diagonal manner. Going too far out of spec will entice gear movement under load when accelerating or in release of load under deceleration, resulting in the reduction of backlash, which causes undue wear, binding, obtrusive noise, and/or driveline vibrations. Shop Gear Set & Install Kits
4WheelToHeal Charity T-Shirt Design Contest
In conjunction with ICON Vehicle Dynamics and Dynatrac, Yukon is supporting Trail Hero and 4WheelToHeal charities by hosting a T-shirt design contest with participants ranging in age from 4 to 15. 4WheelToHeal is a non-profit organization dedicated to serving wounded and disabled veterans of all branches of military service. Their mission is dedicated to taking wounded and disabled veterans/service members from all branches of the military to off-roading events. These events include: four wheeling, rock crawling, mud bogging, off-road racing, shooting, and camping. Our mission is to boost morale, introduce warriors to the fantastic off-road community and give them an experience they will never forget. A full 100% of donations goes toward supporting warrior events. All proceeds from the contest will go toward 4WheelToHeal and the winner will be given family swag packs from our brands as well as have the shirt for sale as the Trail Hero Charity Tee. Drawing submissions will be accepted from July 4th (Independence Day) to August 7th (Purple Heart Day). Click here for more information
New Product: Yukon High-Capacity Aluminum Allison Transmission Pan
Superior cooling is essential for reliable transmission shifting, whether you're on the road, on the trail, or towing heavy loads. Yukon's high-capacity transmission pan is designed with an impressive 11- to 12-quart capacity and strategically placed ribs to significantly enhance its cooling capability. Made for Allison 1000, 2000, and 2400 series automatic transmissions commonly found in 2001-2019 Chevy 2500/3500 pickups, this transmission pan not only performs exceptionally but also looks the part. It features a durable black powder coat finish, high-quality aluminum construction, a magnetic stainless fill plug, and an additional 1/8" NPT plug. While it might seem like you’ll need to flip your truck to impress your friends, your mechanic will certainly appreciate the innovative design and top-notch quality of this transmission pan. It's a valuable addition for those who demand optimal performance and reliability from their transmission.
How To Use A Dial Indicator
The keys to properly using a dial indicator are precision and patience. The payoff is a long-lasting driveline. The dial indicator is one of those specialized tools that has an intimidating reputation, but as with many things, understanding the components of the tool and how they work is half the game. A dial indicator typically measures the backlash of a ring and pinion gear. It can also be used to measure runout, the untrue movement (wobble) of a rotating object like an axle, cam or crankshaft journal, wheel, brake rotor, or the input shaft of a manual transaxle/transmission. Precision is important because in ring and pinion jobs we are dealing with shims that can be paper sheet thin… as thin as three thousandths of an inch. The first step to dial indicator enlightenment is understanding the workings of the tool. Anatomy Of A Dial Indicator When measuring backlash in a ring gear the placement of the dial indicator is key. High-pinion and low-pinion applications have the drive side gear teeth on different sides of the ring gear. This will determine where the dial indicator is set up because measurements are made on the drive side of the tooth. The Setup A dial indicator is like a high-tech erector set. It can be extended and articulated in an array of angles. Setting up the unit starts with the magnetic base which is placed on the housing and then all the armature is configured to position the tip at a 90-degree angle on the drive gear tooth with the plunger in proper alignment with the gear’s rotation angle. A vast majority of dial indicators have magnets that you position to align the plunger and ring gear tooth. In whatever manner the base of your dial indicator secures to the housing, it must maintain a stable platform because every proceeding step relies on the accuracy and consistency of this starting point. Here, the diff housing makes a great anchor point but other applications may not offer so obvious mounting possibilities. The arm can be moved up or down the main shaft while also being adjusted inward and outward within the housing to more precisely line up the tip and the tooth face. This is where your erector set experience comes into play. There is an adjustment knob behind the dial that allows the dial assembly and plunger to swivel to better match the actuation of the tip with the angle of the gear tooth when the ring gear is moved. The goal is to make as much of a straight line measurement as you can. Tighten everything down to limit flex and be sure the tip is resting on the tooth face… any play or preload in this area will produce false readings. Also, be sure the plunger is not rubbing against the adjacent tooth which may also result in a faulty measurement. Shop Yukon dial indicators and measuring tools here. Measuring You can measure with the existing readout or zero-out the tool by loosening the bezel clamp and rotating the bezel. When measuring backlash on a ring gear be sure you’re only turning the gear and not the pinion which may influence the readout. Clamping or otherwise isolating the pinion is a good idea. When measuring a ring gear, the gear is rotated in both directions to produce freeplay. The amount of the movement is measured as straight-line travel by the tip and plunger. Even the runout of a ring gear can be evaluated by measuring the amount of movement the gear produces back and forth between the thrust bushings. Reading The Dial Most dial indicators have a one-inch stroke, meaning the plunger will only move one inch within the tool. The dial indicator’s range is denoted in the dial. The dial also has units of measure or accuracy indicated, typically in drivetrain operations a 1/1000 of an inch is the preferred unit. The main or outer dial is joined by the smaller revolution counter dial which indicates how many times the needle has gone around the outer dial. So, if the main needle travels around the outer dial twice the revolution dial will read 2. Or 0.200 inches. If the larger needle progresses past zero to 30 on the big dial, the total reading is 0.230 or 230 thousandths of an inch. Total Movement The amount of positive movement and negative movement indicated reveals the total movement. So, the measurement is made from the static beginning with the plunger engaged then it moves inward and outward and the number of units measured in each direction are added together. For instance, if the needle moves from plus five thousandths of an inch to minus 90 thousandths of an inch, the total needle movement is 15 thousandths of an inch. Additionally, if the needle moves 10 thousandths of an inch to the negative side and then five thousandths of an inch to the positive side the total movement is again 15 thousandths of an inch. Once you successfully set up the dial indicator measuring other gear sets will be super easy as long as they have the same pinion arrangement i.e. high pinion or low pinion, as the basic setup of the tool’s armature has been established and you’ll only need to fine tune the tip-to-tooth relationship. Dial indicators deserve a place of honor in your tool case. They expand our capacity, allowing us to do more jobs. They add quality to our work, by enhancing the accuracy of our actions. The end result is a job better done that will last for years to come, a win-win in anyone’s book. Shop Yukon Differential Tools
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