randys blog
Suzuki Samurai 5.38 Ring and Pinion Set-Up Tips
It has come to our attention that many customers are experiencing gear failure with the 5.38 gear ratio in a Suzuki Samurai. Through extensive independent laboratory metallurgical testing and testing in our own shop we have determined it necessary to set these particular gears up differently! Standard setups usually call for approximately a .052″ pinion depth shim. We recommend starting with a .059″ to .062″ pinion depth shim. Set up your gear with an ideal contact pattern, and then add approximately .007 to .010″ to the pinion depth shim. This thicker shim, along with the carrier bearing adjuster preload set at 180 ft. lbs. has proven to make this particular combination more reliable. Randy’s Worldwide sincerely hopes this new information will help you attain longer life from your new 5.38 ring and pinion set. Popular Resources: New Gear Break-In Properly Setting Preload with Side Adjusters Size Matters
How It Works: Yukon Dana 30 CAD Delete Kit
What is CAD? What is CAD? It’s not short for Cadillac… In this case it’s not the acronym for Computer Aided Design… For our purpose CAD stands for "Central Axle Disconnect." At its core, the Yukon Dana 30 CAD Delete Kit blocks off the vacuum actuated engagement of four-wheel drive in Dana 30 differentials. Select Jeep vehicles produced from 1984 to 2001 are equipped with the automaker’s reverse rotation Dana 30 differential that’s outfitted with the Central Axle Disconnect (CAD) system. The system components, located on the passenger-side axle tube, consist of a two-piece splined shaft and a coupler that a vacuum-operated shift fork actuates to connect or disconnect the axle, which engages or disengages four-wheel drive. Dana 30 Heritage The Dana 30 has been the go-to front diff for the Jeep Wrangler since the model’s Jurassic Period… CJ-5 models of the early 1970s. Available in high- and low-pinion versions as well as standard and reverse rotation versions, the Dana 30 is an important building block in the Jeep hierarchy. There are tons of aftermarket parts for this differential and spares waiting for rescue in junkyards across the country. CAD Versus The Elements Time is no friend to the CAD system. The vacuum lines can crack, the vacuum motor can fail, or the system can be compromised in another manner, and cause the Jeep to be stuck in two-wheel-drive… that’s no fun. Further, the two-piece axle is not as strong as a one-piece design. Fortunately, the stronger and more reliable one-piece axle from a TJ or ‘non-disconnect’ XJ are direct swaps. The catch… sealing the housing post-swap. Yukon To The Rescue Enter the Yukon Dana 30 CAD Delete Kit. It consists of a disconnect housing blocking plate, gasket, and inner axle seals that will accommodate a one-piece axle design. Yukon Dana 30 CAD Delete Kit Applications 1984 - 2001 Jeep Cherokee XJ 4WD 1984 - 1998 Jeep Cherokee XJ Sport 4WD 1986 - 1992 Jeep Comanche MJ 4WD 1984 - 1991 Jeep Grand Wagoneer ZJ 4WD 1993 Jeep Grand Wagoneer ZJ 4WD 1987 - 1995 Jeep Wrangler YJ 4WD End Of The Trail The Dana 30 has been around since the prehistoric days of the Jeep brand… and it’s not going anywhere. Neither is Yukon Gear & Axle. We have a vast inventory of replacement parts that will keep Dana 30s on the road and performance products that will improve the breed. Happy Wheeling. contact us at 866-631-0196 Shop CAD Delete Kits
Tales From The Tech Line: Burnt Gear Blues
Tech Question: I've been having some issues with ring and pinion failure in a Chrysler 8.25” differential that’s in a ‘98 Jeep Cherokee. The first set failed in about 4,000 miles and the set that’s currently in it is on its way out as well. I'm by no means a Diff Wizard, but I have setup many with no failures until this particular case. After the first set failed I just bought a replacement and chalked it up to me overlooking something. That being said, when I rebuilt the diff the second time I paid very close attention to the details to avoid any mistakes but ended up with the same results. I have shown the gear set to a few colleagues that have setup more diffs than I have and no one seems to have a good answer why it happened the first time, much less twice. When the first set started to howl or whine I pulled the cover thinking it was a pinion bearing going bad only to find the gears had worn enough that the backlash was out to .060 inches. None of the teeth were damaged on either the ring or pinion but all were worn down substantially. When it happened again, I removed the cover to find the same result, although not as worn as I caught it sooner. Backlash on the set that’s still installed is out to .035 inches currently. The locking tabs are still in place as they’re supposed to be. I checked them to make sure the adjusters hadn't backed off allowing the extra backlash. Both times the pinion bearing preload was still within spec. I also checked to see if I had failed to get a race fully seated but they were fine. Any help or info would be greatly appreciated! Thanks, R. H. - Indiana Tech Answer: Examining your pictures, it looks like the initial setup is acceptable and not likely the cause of the issues you are having. The break-in process may be the culprit here. This burnt ring gear shows the telltale signs of heat damage due to improper break-in: Coarse grain structure (red ovals) on the teeth where there should be a mirror-like finish and fracturing across the face (yellow arrows). There are a few things happening. The first and most obvious, is gear meshing. During a proper break-in process as the temperature rises and pressure is applied, these forces harden and compress the grain structure by lapping or polishing the gear teeth surfaces. This creates a nice smooth surface for the teeth to glide across with minimal friction. If you look at the images of yours, they are still very coarse and have an exposed grain structure. Another variable that is often overlooked is how, during the cool down process, the oil “quenches” the gears. This is just like in knife-making where the metal is super-heated then cooled in an oil bath. This process slightly changes the metallurgy on the surface of the gear face, transferring carbon etc. because we don’t want the gears glowing hot like in the manufacturing of knives. This heating and cooling cycle is repeated over and over in the drive cycles during gear break-in. Properly breaking in deep gears on a small diff can be tough. The contact area is reduced, there is less metal in the pinion head to work as a heatsink, etc. Combine these factors with a gear set that spins fast can be compared to drilling a hole in a piece of steel with too high of a drill speed. You generate more heat than what the oil can dissipate, the oil cooks and loses its ability to lubricate, and the bit burns… compromising the cutting edge on the bit. Looking at the teeth on your gear set, this seems to be what is happening. The oil is likely breaking down due to highly elevated temps, losing its ability to both dissipate the heat and provide proper gear lubrication. Once the oil gets this hot, it never really recovers. Sure, it will cool down and provide some cooling and lubrication, but not at the levels it once did. When internals get that hot during the break-in period gear meshing can also end up peeling the hard face that the initial break-in has built up. This is why your backlash changes. You have fractured and peeled off the hard face, exposed a rough grain structure, and taken the condition of the metal back to pre-break-in condition. Then you start the process all over again with even rougher gears… it’s a downward spiral. The problem is compounded because gear geometry has slightly changed as the teeth are thinner/smaller. Sure, you can reset the backlash to tighten it up and “fix” one of the variables, but it doesn’t address the real problem. Another often overlooked issue is airflow cooling from under the vehicle. Running at highway speeds airflow on the diff actually becomes stagnant. It’s common to see gear sets burn not from actual overloading, but from driving too fast for too long and doing it too soon. Light throttle cruising at freeway speeds early in the break-in process, while seeming to be easy on parts, can generate more heat than the diff is able to dissipate. I find that this kills more gear sets than anything else during the break-in process. My recommendations… Run a quality 80-90 GL5-rated conventional gear oil. Take it easy during the break-in process… short drives to get up to temp, let it cool to ambient temp, repeat. If you suspect that you might have gotten too hot, change the fluid, conventional gear oil is cheap. Remember, there is no filtration inside a diff, the only way to get wear particles out is to drain the diff, clean it, and refill. Conventional gear oil also has a slightly different carbon structure compared to synthetic oils and I find that conventional oil does a better job “quenching” the gear set. It also doesn’t seem to thin out as quickly and clings to parts better. Gus Pyeatt, RANDYS Worldwide Tech Support For more info on gear set break-in procedures check out this video.
Decoding Differential Tags - Video
Auto manufactures have made it possible to glean basic but useable differential information by means of tags, stickers or stampings on the differential. The tags are usually affixed to the pumpkin by a diff cover bolt and stickers can be on the housing or axle tube close to the housing. The “direct from the source” aspect of this information makes it hyper accurate, overriding any confusing make, model, engine, and transmission information mash-up. No late night research needed. It’s all right there, straight from the manufacturer. The accompanying videos outline what info is on Ford and GM tags and what it means to you.
How to Identify Your Differential and Axle Type
How to Identify Your Differential and Axle Type Using year, make and model, and vehicle info is the first/best way to identify your differential. But there are cases where these facts come up short. Your vehicle’s options like tow packages, off-road packages, or whether it sports an automatic or manual transmission can make identification more difficult. Further, if your rig has been modified its drivetrain changes will throw a wrench in the works. Luckily, there are visual cues that can help identify your particular diff or axle. Cover Bolt Count Since most differentials have a unique cover bolt pattern i.e. 10-bolt, 12-bolt, or 14-bolt, counting them up will narrow the field and help you with identification. While focusing on the pumpkin check out what type of housing you have… an integrated housing or a drop-out style. An integrated housing can be spotted by its inspection cover. A drop-out housing has no inspection cover because the entire differential assembly is removed from the front half of the housing. Axle Flotation Another important data point is axle type. There are two types of axles, semi float or full float. Semi-float axles have larger flange diameters than floating axles and the wheel bolts to the flange. A full-float axle flange bolts to the wheel hub and can be removed without taking the wheel off or jacking the vehicle up. Another variable to consider concerns how the axle is secured within the differential... via a c-clip or by bolting the unit in place. Get Your Spline In Line While identifying your axle shafts, it’s important to take note of your spline count. Look at the raised teeth and count these out. This can be tedious. We suggest marking a spline with a Sharpie and starting your count there. You may want to do a recount or two to confirm you’re tally is accurate… we told you it may be tedious. Spec Out Your Hub Another helpful hint in identifying your axle is figuring out how many hub bolts you have, your hub pattern, and your hub diameter. Determining the number of bolts is relatively easy, determining the bolt pattern can be a little more complicated. The best way to do that is by measuring from one stud to the center of the axle flange itself and doubling that number. If you see yourself doing this a lot, there are bolt circle templates that will expedite the procedure. Knowing your hub diameter will help in identifying different years, makes, and models. Pinion Size & Ring Gear Diameter Once your differential is disassembled and its parts removed, it’s time to measure your ring gear to determine its diameter. Simply measure from the widest point of the gear, tooth tip to tooth tip Pinion nut size is another parameter that can be used to identify the diff. This is relatively ease just test fit sockets until you find the one that fits… bingo. For more differential spotting tips check out the accompanying video.