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Tech Tidbit: Common Steel Groups for Axles
Typically, steel is rated by the SAE or the ASM according to its particular elements. Proven and standardized “recipes” are issued a four-digit number. The first two signify the steel group, i.e. carbon steel, nickel-chromium-molybdenum steel, etc. The second two indicate the carbon content in hundredths of a percent, which is variable according to end use. 10XX, 11XX, 12XX, 15XX = The carbon steel group. Most standard OEM axles are 1040 grade. OEM axles are generally heat treated to 40 Rockwell in the center with the outer layer at 55-60 Rockwell to a depth of about .180 inch. These grades all carry from 1.00-1.65% manganese. The industry differentiates these steels by their carbon content, i.e., “low carbon” and “high carbon” steels. The last two digits “XX” indicate the carbon content of the steel. A “30” indicates 3% carbon, “40” indicates 4% carbon, and so on. 13XX = This manganese steel group contains 1.45-2.05% manganese. If it contains 1.6-2.05% manganese, it can be called an alloy steel. This grade is used by aftermarket axle builders because the high manganese content allows for more flexibility during the heat treating process. Some 15XX steels have 1.6-2.05% manganese. 41XX, 43XX, 47XX, 86XX = The nickel chromium-molybdenum group. An alloy containing .65-.95% chromium, .2-.3% molybdenum and 1.55-2.0% nickel. Chromium increases hardness and the elastic limits (when the material is quenched), as well as increasing corrosion resistance. Molybdenum and nickel also increase hardness. “H” Rated = There is a whole range of “H” rated steels that will match the composition of the standard type, such as 1340, but will contain a measure of silicon. Silicon comes from quartz and sand and when mixed into steel it adds a measure of hardness and can improve or increase the heat treating options. 1340H, for example, has .15-.30% silicon. “M” Rated = These are modified steel, where the “recipe” of a rated steel has been given slight enhancements to improve or alter its characteristics. Two are commonly seen in the axle world, 1541M and 4340M (a.k.a., 300M). Comparison of Steel Properties* SAE Grade Tensile Strength Yield Strength 1040 120,000 psi 106,000 psi 1050 162,000 psi 146,000 psi 1541H 181,000 psi 164,000 psi 4340 228,000 psi 210,000 psi *Typical, as used in the actual product, including all heat treatments. Some specific recipes might be higher or lower. This represents an industry average. Popular Resources: Limited Slips: Gov-Lock vs. Yukon Dura Grip Identifying Borg Warner Transfer Cases Limited Slips vs. Differential Lockers vs. Spools
Tech Tidbit: U-Joint Specs & General Applications
It’s obvious u-joints are a critical component in any driveline so understanding their key mesurements and general specs is important. We have put this spotter’s guide together to answer some of the basic questions regarding universal joints. Parameters such as cap diameter, ring diameter, and the availability of adapters are outlined. There is also a listing of common applications for each class of u-joint. U-Joint Diameters & Specs U-Joint Cap Diameter Snap Ring Diameter Adapter Available 1110 Series 1 1.718 1310 to 1330 1310 Series 1.063 2.375 1310 to 1350 1310 Series 1.063 2.375 1310 to 3R 1330 Series 1.063 2.781 1330 to 3R 1330 Series 1.063 2.781 7260 to 7290 1330 Series 1.125 2.781 1330 to 7290 1330 Series 1.063 2.563 1350 Series 1.188 2.563 1410 Series 1.188 3.125 Mechanics 3R 1.125 2.563 Detroit 7260 1.078 2.125 Detroit 7290 1.125 2.625 General Applications General Motors: 1310 Series: Small passenger car, 1/2 & some 3/4 ton trucks. 1330 Series: Large passenger car, medium 1/2 ton trucks. 1350 Series: 3/4 & 1 ton trucks. Mechanics 3R: Late passenger cars and 1/2 ton trucks. Kevlar Drive Shaft: Rear – DAN 5-212X Front – DAN 5-213X. Ford: 1110 Series: 4 & 6 Cyl. passenger cars. 1310 Series: Small passenger cars & many 1/2 & some early 3/4 ton trucks. 1330 Series: Large passenger cars & many 1/2 & 3/4 ton trucks. 1350 Series: 3/4 & 1 ton trucks. DAN 5-2011X: Small Early Mustang. Chrysler: Detroit 7260: Small & medium passenger cars & many 1/2 & 3/4 ton trucks. Detroit 7290: Medium & large passenger cars & many 1/2, 3/4, & 1 ton trucks. 1350 Series: Some 3/4 & 1 ton trucks. 1410 Series: Late 3/4 & 1 ton trucks. Toyota: DAN 5-1510X: 1/2 ton 4WD trucks.
Size Matters: The Ring Gear To Pinion Tooth Relationship
Whenever the gear ratio in a differential is changed, pinion diameter changes. There are two things that must change in order for the gear ratio to change. First, some basic information. The gear ratio is determined by the tooth combination. The number of teeth on the ring gear divided by the number of teeth on the pinion (eg: 41/11 = 3.73) equals the gear ratio. Also, in order for the teeth to have the proper mesh and contact, the relative size of the two must be changed to match the ratio. If the gear ratio is 3.00 to 1, the distance from the pinion shaft centerline to center of the pinion teeth must be 1/3 the distance of the center of the ring gear teeth to the ring gear center line. This means that the pinion shaft is roughly 1/3 the diameter of the ring gear for a 3.00 to 1 gear set. This also means that the pinion size for a gear set that is 5.00 to 1 must be only about 1/5 the size of the ring gear. The ring gear diameter is generally constant for any particular differential design regardless of the ratio. This means that the pinion size changes with the ratio and for lower gears (higher numerically) the pinion teeth are smaller. There are a few problems that go hand in hand with a small pinion head. The first are the facts that there are either smaller pinion teeth or fewer of them. The smaller teeth have less material supporting the load surface and it is a lot easier to break them off. In cases where there are fewer pinion teeth, there are fewer teeth contacting the ring gear teeth at once. In taller gears (lower numerically) such as 3.08’s, there are about two pinion teeth contacting the ring gear at any time. During the transition from tooth to tooth as the assembly turns, there may be half of one tooth contacting in the lead in position while another tooth has full contact in the center, and the trailing or exiting tooth may have half contact. This makes for smoother transitions from tooth to tooth and increases strength. In a situation where the ratio is extremely low (numerically higher) such as 5.71, there may only be about one tooth contacting at a time. The transition here goes from a fraction of a tooth on the lead in position and almost full contact on the trailing tooth, to almost full contact on the lead in and only a small fraction of contact on the trailing tooth as the ring and pinion gears rotate together. The main point is that there is not much contact to carry the load when the ratio is numerically high. Many off-roaders are aware of this problem and still kid themselves into thinking that they will not have the same problems is they only drive carefully. Yeah, right. Some Toyotas, some Jeeps, and many small or mid size vehicles use differentials that do not lend themselves well to tall tires and low gears. The diameter of the ring gears are limited by the housing designs and the best way to re-gain strength is to upgrade to a larger differential. Why not make the ring gear smaller or larger? The ring gear diameter is limited by the carrier case that it bolts to, and by the amount of room in the housing. Some of the high-speed freeway ratios for the 9-inch Ford such as the 2.50’s and the 2.41’s use a ring gear that is slightly smaller in diameter than 9″ because there is not enough room in the housing for a huge pinion head to fit. Before you start thinking of some way to extend this idea into something that helps the off-roader, there is a solution that is already available. Upgrade to a differential that uses a larger ring gear and pinion set. Even the commonly worshipped Dana Spicer Model 44 does not hold up well to tall tires and ratios in the 4.89 plus range due to its 8-1/2″ ring gear and short teeth. Some of the larger designs such as the 9″ Ford or Dana 60 are worth the time and money if tall tires or other conditions require low gears. The 9″ Ford uses a very large hypoid offset that reduces ground and driveline clearance but definitely increases strength. The Dana 60 provides more strength through sheer size. The D60 uses a 9-3/4″ ring gear and huge bearings to support the pinion shaft. Even with ratios in the 7.17 range this is still a very strong differential. Some other options are the Toyota Land Cruiser, the 14 bolt Chevrolet, Dana 70’s, Dana 80’s (this one is truly HUGE), and the 8-3/4″ Chrysler. Find a competent chassis builder, off-road shop, or complete differential shop and they can help you find the differential that is best for your application.
Yukon 2021 Holiday Gift Guide
Santa’s gearing up for his big trip south. If you have car enthusiasts on your list and are having a hard time checking off some boxes, the Yukon Holiday Gift Guide is here to help. From fashionable apparel for their stockings to hardcore driveline parts that will look great under the tree, this guide has something to make the season brighter. Can’t decide? Test drive one of our nifty gift certificates and let them choose. Shop Holiday Gift Guide
12 Tech Tips For Differential Assembly & Setup
This quick primer of tech tips is designed to be informational for less experienced installers and a refresher course for seasoned differential technicians. The focus is on time-saving tricks and advice when assembling and setting up a differential, concentrating on preparation, assembly, setting pinion depth, backlash, and more. Anatomy Of A Gear Tooth In order to take full advanatge of the tips and information conveyed in this article we need to get our lingo on the same page. The above schematic outlines the surfaces of a typical gear tooth and how they are generally referred to. 1. Take The Right Approach The order in which adjustments are made during differential assembly and setup are: 1. Pinion Depth 2. Pinion Bearing Preload 3. Backlash 4. Carrier Bearing Preload 2. Pattern Adjustment Cause & Effect Use shims to move the ring gear closer to the pinion to decrease backlash. Use shims to move the ring gear farther from the pinion gear to increase backlash. Use shims to move the pinion closer to the ring gear to move the drive the pattern deeper on the tooth (flank contact) and slightly toward the toe. The coast pattern will move deeper on the tooth and slightly toward the heel. Use shims to move the pinion farther away from the ring gear to move the drive pattern toward the top of the tooth (face) and slightly toward the heel. The coast pattern will move toward the top of the tooth and slightly toward the toe. 3. Remember Your Shim Combination When it comes to shim selection use the same shim combinations from the previous assembly as a baseline when reassembling the differential. 4. Seal Surface Preparation It is wise to polish all seal surfaces with fine-grit emery cloth or sandpaper then wipe all surfaces with a clean rag dampened with either fresh oil or solvent to remove any metal particles. 5. The Importance Of Using Assembly Oil When assembling internal components, coat all bearings and seal surfaces with fresh gear oil. Never use bearing grease on pinion or carrier bearings because it will negatively influence assembly measurements. Coat all seals with grease, preferably white lithium grease. Use clean gear oil if white grease is not available. 6. Trial Pinion Assembly Mock install the pinion with its original shims yet without a crush sleeve to establish an approximate pinion depth. When installing the pinion, tighten the nut slowly until it reaches preload specifications. 7. Initial Carrier Assembly Install the assembled gear carrier with its ring gear into the housing. It is easier to remove and replace the carrier during trial assemblies if the carrier bearing preload is fairly snug instead of tight. 8. Initial Backlash Adjusting Tip Backlash refers to the amount the ring gear can rotate forward and backward when the pinion gear cannot move. The initial backlash setting establishes the basis for all future adjustments. To start, fasten a dial indicator to the gear case or axle housing on the same plane as the ring gear so its contact point touches a tooth at the outermost diameter of the ring gear in a 90-degree relationship to the tooth face. The indicator should measure the amount the ring gear moves when rotated. To measure backlash, prevent the pinion gear from rotating and rotate the ring gear back and forth. The amount the ring gear can move (the amount of play) determines the amount of backlash. When changing the backlash bear in mind that the backlash setting changes about 0.007” for each 0.010” that the carrier moves. For example: Move the carrier 0.010” toward the pinion to decrease the backlash by 0.007”. Move the carrier 0.010” away from the pinion to increase the backlash by 0.007”. This gear pattern indicates the pinion is too close to the ring gear centerline. Use shims to position pinion away from centerline. This gear pattern depicts a pinion that is too far way from the ring gear centerline. Use shims to position pinion closer to the centerline. This is the proper or desirable pattern. Note how the pattern is centered on the tooth from face to flank. There should be some clearance between the pattern and the top of the tooth (face) and between the pattern and the bottom of the tooth (flank). Learn more about ring gear patterns in our “How To Create & Read Ring Gear Patterns” article. 9. Make Large Pinion Depth Adjustments First When changing pinion depth, make large changes until the pattern is close to ideal. Consider 0.005” to 0.015” a large change and 0.002” to 0.004” a small change. Intentionally, make adjustments that move the pinion too far at first. If the pinion moves too far and the pattern changes from one extreme to the other, the correct pattern lies somewhere between the two extremes. Once you home in on the correct pinion depth, make smaller changes until the pattern centers between the face and the flank of the ring gear teeth. Once the backlash and pinion depth meet tolerances, remove the carrier and establish the final pinion bearing preload. 10. How To Fine Tune Backlash If the preload is close and the backlash is too loose, tighten the left adjuster a notch or two until the backlash is correct and the preload is sufficient. If the preload is close and the backlash is too tight, tighten the right adjuster until the backlash is correct and the preload is sufficient. Note: ensure that the last adjustment made to the left adjuster tightens it. Doing so will eliminate the possibility of a space between the adjuster and the bearing race. 11. Shimming Outside Shim Design Carriers This design uses shims between the carrier bearing races and the housing. Initially, set the backlash with very little carrier bearing preload. After setting the backlash, add equal amounts of shims to both sides of the carrier to set the carrier bearing preload as tight as possible without damaging the shims (carrier bearings in this axle design hardly ever fail due to excessive carrier bearing preload). If the preload is close and the backlash is loose, add shims to the left side. This increases the carrier bearing preload and tightens the backlash at the same time. If the preload is close and the backlash is too tight, add shims to the right side. This increases both the carrier bearing preload and the backlash at the same time. 12. Shimming Inside Shim Design Carriers This design uses shims between the carrier bearing and the case. Initially set the backlash tight and the preload light, as it will make carrier removal and installation easier. After setting the backlash, add equal amounts of shims to both sides until the correct preload is achieved. If the preload is close and the backlash is loose, add shims to the left side. This increases the carrier bearing preload and tightens the backlash at the same time. If the preload is close and the backlash is too tight, add shims to the right side. This increases the carrier bearing preload and the backlash at the same time. Shop Re-Gear Kits