symptoms of too much backlash

Do you confirm the issue by checking the lubricant in the diff for metal wear particles and then arrange to have the vehicle referred to a specialist repairer? RING AND PINION TOOTH CONTACT PATTERN.- The ring and pinion tooth contact pattern is used to double-check ring and pinion adjustment. High amplitude sidebands around 1, 2 and/or 3x GMF at 1x rpm of one or both of the gears. While “Heel” and “Toe” are largely self-explanatory, the other two terms (with more following) may not be clear if you have not had much exposure to differential repair/rebuilding. 4.2k. Under these conditions, the pinion gear is the drive gear, and the ring gear is the driven gear. Rand Paul responds to coronavirus backlash: 'Perhaps it is too much to ask that we simply have compassion for our fellow Americans who are sick' Jake Lahut Mar 24, 2020, 00:33 IST Iron overload disorders, including hemochromatosis, cause the body to absorb too much iron. The ring gear is usually a separate component that bolts onto the ring gear carrier, which is supported by two bearings- one on either side of the ring gear. I checked the pattern a few more times just to be safe and it seemed the more I played with it, the more my backlash tightened up. This refers to the side (or face) of the ring gear teeth that are in contact with the pinion gear when engine power is removed from the differential, such as when the vehicle is coasting. This eliminates mechanical noise while at the same time, keeping the gear teeth in contact with each other over the biggest possible contact area if the differential is set up correctly. Some symptoms that are more common in the hyperactive/impulsive type are: Acting impulsively; Feeling restless or fidgeting; Having a hard time waiting; Talking too … Over, and we'll have some more noise, and extremely over will also result in damage. In both situations, there will be an insufficient backlash and more likely than not, unmistakable evidence of severe mechanical wear on the teeth of both gears- apart from whining, grinding, or rumbling noises under all operating conditions, Contact patterns that tend towards the top of the ring gear teeth indicate that the ring gear offset relative to the pinion gear is excessive, which results in excessive backlash and mechanical noises such as whining during both loaded and coasting conditions. I've been getting concerned about my driveline. Intake and exhaust valves that are not adjusted to open and close at the proper times degrade an engine's ability to make maximum power. Note the names of the areas on the ring gear. While differentials do not involve reciprocating masses, the built-in resistances in a properly set up differential maintain a situation in which one tooth on the pinion gear comes into contact with a tooth on the ring gear at the exact moment that a tooth on the pinion gear loses contact with a tooth on the ring gear. google_ad_width = 728; Backlash is part of the differential story, we need a good contact pattern. The Symptoms of Backlash. How much is too much? This distance is application-specific* and is critically important on all differentials because insufficient backlash causes the gears to bind, while excessive backlash causes excessive mechanical wear. While there is a significant clearance between a cam lobe and a cam follower or tappet, the various resistances and reciprocating masses in a valve train prevent the cam followers and the cam lobes from slamming into each other to create the typical tapping noise we all love to hate. If you raised too much energy and have too much of it swirling around in your energy field still, you’ll probably feel anxious, wired up, agitated, and you may get body aches. The result is that gear teeth slam into each other on either the drive or coast sides of the ring gear teeth (depending on operating conditions) which is what creates the whining noises in differentials that we all love to hate. Broken lifters and burnt pushrod tips are often consequences of too much valve lash. Make sure you use a new gasket. Fixing or rebuilding differentials is admittedly not everybody's cup of tea, but on the other hand, differentials are not nearly as complicated or difficult to diagnose or set up correctly as you might have been led to believe. * Note that because of the fundamental differences between differentials in rear axles and differentials that are incorporated into FWD transmissions, this article will focus solely on differentials used in rear axles on RWD vehicles. While sudden, catastrophic gear failures are exceedingly rare on standard applications that are not abused, most differential failures involve whining, grinding, or rumbling noises either upon acceleration when the differential is loaded, similar noises when the vehicle is coasting, or in severe cases, a rumbling or grumbling noise when the vehicle is steered around bends and corners. The symptoms are: 1) The whine usually starts after the differential oil has warmed up. The reality isn’t so simple, as Ian Carr, Managing Director of Drive Line Technologies, explains: there are times when backlash is unacceptable; other times when it does not really have any effect at all; and sometimes when controlled backlash is actually a benefit. Conversely, if the spacer is not crushed enough, you get insufficient backlash, so by crushing this spacer, you can adjust the position of the pinion gear relative to the ring gear. Well, I got my rear end in this evening. Figure 5-21 shows several ring and pinion gear contact patterns. In terms of diagnostics, however, the contact pattern is the most valuable aid you will have because this pattern is a direct function of how the differential is set up, so let us consider the image below-, The above image shows some examples of contact patterns that you are most likely to see on noisy differentials, but to understand how these types of contact patterns come about you need to understand how the pinion and rings gears are positioned relative to each other. Study each and note the suggested correction for the faulty contact. It is probably a natural reaction to assume that backlash is a bad thing which needs to be designed out of every engineered system. This measurement has huge diagnostic value but to be reliable, TTP values must be obtained with the driveshaft, wheels, and brakes removed from the differential. The center distance is a little high in all three stages, but from what you have said, probably not enough to weaken any of the gears very much. Figure 5-20.- Measuring ring gear runout. This arrangement makes it possible to have two teeth on the pinion and two teeth on the ring gear in contact with each other, unlike straight-cut gears where only one tooth on each gear can be in contact with each other. Me Too Backlash Is Getting Worse. the stock original axles have 250.000 miles where as the diff has 28.000. When used gears are adjusted properly, the contact pattern will vary from that of new gears. The other symptoms that might be related and make me worry that this is excessive play are a slight clunk when changing into drive/reverse and also a slight readjustment (sliding forward or backward) after putting the car in park, shutting the engine and releasing the brakes. In the first method, it sometimes happens that some gear teeth are cut deeper than others, while in the second method all the gear teeth are cut to the same depth. In this example, the areas on the gear teeth where the yellow marking paint has worn off extend over both the full length and total depth of the ring gear teeth, which is the desired condition**. A 12-ounce cup of black coffee contains 260 mg of caffeine while a Red Bull has 80 mg. Dizziness and diarrhea are symptoms you’ll find when you’ve had too much caffeine. What you should've said is that backlash adjustment within the specified envelope will have minimal effect....incorrect backlash settings will cause the contact pattern to either move too deep (if not enough backlash) or towards the outter edge of the ring gear teeth (if too much backlash). NOTE: Differential backlash is somewhat analogous to valve clearances. Thus, there is a very good chance that a significant percentage of vehicles are sold and exported to international markets with differentials that are built to fail: the infamous "Chevy Shake*" being a good case in point. If however, the backlash is excessive, there is a brief moment during which two gear teeth lose contact with each other before contact between the next two gear teeth is established. The infill does not touch the parameters. All of the above terms and their definitions bear directly on how to diagnose differential issues, as well as how to set up a differential during repair/assembly procedures. A loose or high backlash (too much), is corrected by shimming the differential and moving it closer to the pinion gear. Below are some-, Image source:, The image above shows a typical differential ring gear with some important labels added. This refers to the face (or side) of the gear teeth that are in contact with the teeth on the pinion gear when the differential is loaded upon acceleration, or during cruising conditions when constant power input is required to maintain the vehicles’ momentum. If the valve lash is set incorrectly (too much clearance, or not enough), the engine may respond by running rough at idle, particularly while warming up. Nonetheless, the principal causes of differential failures are much the same across all applications and could include one or more of the following, but in no particular order-, The above points cover a lot of ground, and while it is not always easy to distinguish between cause and effect when it comes to diagnosing differential issues, you can remove a lot of guesswork from the equation if you know and understand some of the basic terms that pertain to differential repair. This distance is application-specific* and is critically important on all differentials because insufficient backlash causes the gears to bind, while excessive backlash causes excessive mechanical wear. I measured it in my driveway and it moves about 4 1/2 inches. A stunning 60% of male managers said they’re uncomfortable mentoring, working … Thus, if all the bearing pre-loads in a differential are correct, all the rotating components in that differential will a), only rotate around their axes of rotation and b), will be unable to orbit their axes of rotation or move in longitudinal, radial, or transverse axes relative to their planes of rotation. Much of that force is reflected back through the rocker and pushrod to the lifter. COVID-19 updates See our safe care and visitor guidelines, plus trusted coronavirus information. Let us start with-. In some cases, the vibrations correlate with mechanical noises upon either or both acceleration and deceleration, but experienced technicians will agree that in many cases, the standard remedies do not cure the persistent vibrations. - Tighten the bolts according to the manufacturer's specifications to prevent them from working loose.,, Differential Noise & Vibration: Here’s How to Diagnose the Problem, Excessive mechanical wear of gears and bearings caused by poor, inadequate, contaminated, or unsuitable lubrication/lubricants, Excessive backlash (clearance) between the pinion and ring gears, Inadequate backlash (clearance) between the pinion and ring gears, Shoddy or poor workmanship during the initial assembly/setting up that results in either excessive or insufficient bearing pre-loads, Contact patterns that tend towards to outside edge (Heel) of the ring gear have several major effects apart from causing whining noises. ('57 Golden Hawk, non-TT) Got the assembly OUT (originally just to clean), and found HORRIBLE spalling and pitting on the bearing races (inner axles). Rand Paul responds to coronavirus backlash: 'Perhaps it is too much to ask that we simply have compassion for our fellow Americans who are sick' Jake Lahut 3/23/2020 New COVID-19 symptoms Symptoms of too-tight backlash??? Note that both inadequate and excessive backlash can cause varying mechanical noises. Note that these figures exclude differentials produced for use on passenger or high-powered muscle cars. Reinstall the axle shafts and new gaskets. Circles are elongated or squarish i.e., not round. Privacy Statement - google_ad_slot = "4562908268"; I find that the given specs are not always easy to measure or achieve. This value is also application-specific and refers to the amount of force (torque) that is required to rotate the pinion gear via the pinion nut with a deflecting beam or digital torque wrench. Under these conditions, the ring gear becomes the drive gear, and the pinion gear becomes the driven gear because, under coasting conditions, the differential is loaded by the rotation of the wheels, instead of by the engine via the driveshaft. Notice that the ideal tooth pattern on new teeth is uniform on both sides, whereas the used gear indicates considerably more contact on the coasting side. That's roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks. To increase backlash, move the ring gear away from the pinion gear. Then, while holding the pinion gear STATIONARY, wiggle the ring gear back and forth. Proper pinion depth and backlash will certainly help ensure this. Understand the risks of too much vitamin D, including a toxic reaction. This, in turn, causes destruction of the pinion shaft bearings, which results in severe driveshaft-like vibrations because the destroyed bearings cannot support the pinion shaft. By Emily Peck. Note that on some differentials, the position of the ring gear is controlled by large lockable nuts instead of by shims and/or spacers, which brings us to the topic of-, While limited space precludes a comprehensive discussion of contact patterns and their effects, it is worth mentioning that-. The image above shows an almost perfect contact pattern*. Some books give exact specifications of how much preload to add to the carrier bearings. 5-21). Provided that proper lubrication is available at all times and that the differential is set up properly and correctly, most differentials outlast the vehicles they are fitted to. The above statistics might seem irrelevant, but the point of it is this; it is simply impossible to set up every one of many millions of differentials correctly all of the time- even with the highly refined mass-production methods and stringent quality assurance/control checks that manufacturers pride themselves on. 11-12-2016, 06:47 PM. ** Note that since a given ring gear could have been manufactured in one of two ways, it is sometimes not possible to achieve the type of contact pattern shown above. This means that you have backlash on the Y-axis. After I set the gears up and got a good pattern, I pressed the final bearings on and put it all together. Of course, this is not the same as saying that you couldn’t do it if you tried, but your employer will almost certainly not allow you to learn how to repair or rebuild a differential on a paying customer’s vehicle. However, too much ring and pinion backlash can cause gear noise (whirring, roaring, or clunking). In general, backlash in gears is play between mating teeth. To measure ring and pinion backlash, position a dial indicator stem on one of the ring gear teeth. Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. Howdy, I'm new here to the forum and I'm already up with a question....i'm running a 93 4x4 with a relatively new differential from randys ring and pinion, after 28.000 miles there seemes to be excessive backlash between pinion flange and axle....would worn axle splines at the diff- be the cause of noise yet. For example, if you need to change the backlash by .004-inch, shim(s) measuring .006-inch is a starting point. To check the accuracy of your adjustments, coat the ring gear teeth with a thin coat of red lead, white grease, hydrated ferric oxide (yellow oxide or iron), or Prussian blue. * Contact patterns are obtained by removing all traces of lubricant from the ring and pinion gears with a suitable solvent before paining both sides of all the ring gear teeth with special marking paint, or failing that, a high-quality spray paint. How much slop should be in my yoke coming out of the D20. What is your first reaction when you are presented with an RWD, 4WD, or AWD vehicle that is exhibiting clear symptoms of a worn or damaged differential? Indicator needle movement will equal gear backlash. This equates to 32 876 units per day, 1 370 units per hour, or more to the point, 22.83 units per minute. Typically, stomach pain and diarrhea occur in conjunction with nausea … Likewise on the jacking one side of the car up and twisting the raised wheel back and forth. You're going to feel any and all slack from the wheel on one side to the wheel on the other. As the gears operate, they produce friction and heat. However, you could do the next best thing, which is learning how to diagnose differential-related issues and problems accurately because doing so would give you two major advantages over your colleagues. However, one very important term, “gear contact pattern” has not been discussed, so let us look at how to you can use this term in-, Image source: However, too much ring and pinion backlash can cause gear noise (whirring, roaring, or clunking). Sidebands at 1x rpm surrounding the resonant frequency. Compare your measurements to the manufacturer's specifications and adjust as needed. Consider this: reputable sources claim that American manufacturers produce about 12 million differentials intended for use on 4WD and AWD vehicles every year. Learn about the causes, symptoms, and treatments here. Note that if the contact pattern on the drive side of the ring gear teeth is acceptable, it is almost certain that the contact pattern on the coast side of the ring gear teeth will also be acceptable. This makes the gears expand, reducing the clearance between the meshing teeth of the gears. Figure 5-20.- Measuring ring gear runout. Nonetheless, the fact is that while anybody can learn to repair or rebuild differentials, actually performing these procedures to industry standards requires dedicated training and practice (and lots of practice, at that) which leaves us with this-. If you have not had the required training, this writer would advise against trying to repair a differential as an experiment just to see if you could do it. If you do have backlash woes what would the most likely symptoms be? Therefore, n TTP value that exceeds a specified value is indicative of excessive bearing pre-loads and/or insufficient backlash, while a TTP value that is lower than specified is indicative of insufficient bearing pre-loads and/or excessive backlash. Copyright Information. Excessive Backlash Symptoms: Higher amplitudes at 1, 2 and/or 3x GMF. Once the backlash has been set, the carrier bearing preload can be added. One manufacturing method involves cutting each gear tooth separately, while the other method involves cutting several gear teeth simultaneously.