Wavetrac is saying, by design, you will have zero "backlash" internally of the LSD. It's seamless with loading and unloading of applied torque. And I agree. Although, it's not alone in concept, it's probably the most efficient at doing it.
• Innovative: Patent pending Wavetrac® design automatically improves grip in low traction conditions. This feature is truly innovative and unlike any other torque biasing diff design. • Superior Materials: 9310 steel gears run in case-hardened billet steel bodies. ARP® fasteners used throughout. • Maintenance Free: As supplied new, the Wavetrac® differential will perform a lifetime of service without maintenance or rebuilds. • Customizable: If desired, you can alter the diff’s behavior to suit your needs using optional components. • Limited LIFETIME Warranty: All Wavetrac® differentials include a transferable, Limited Lifetime Warranty. To best understand how the Wavetrac® is truly different from the other gear differentials on the market, you first have to understand the primary problem that the Wavetrac® solves. The problem: Loss of drive during zero or near-zero axle-load conditions. Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions. Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drivetrain, when one drive wheel is nearly or completely lifted (often in aggressive cornering). It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground. Here’s how that loss of drive hurts you: 1) If you lift a wheel, all gear diffs except Wavetrac®, will NOT power the other wheel. 2) During the transition from accel to decel, all gear diffs except Wavetrac®, do nothing. Why does this happen? All gear LSDs (including Torsen®, Truetrac®, Quaife®, Peloquin, OBX, etc.) work in basically the same manner: they divide the drive torque between the two axles, applying drive to each side, up to the available grip of each tire. The amount of drive torque one wheel can get over the other is described as the bias ratio, a measure of the torque split across the axle. Standard, open differentials have a bias ratio of 1:1. They can only apply as much drive torque as there is available traction at one wheel. When one wheel loses grip, the total available drive is lost as well (at a 1:1 ratio). All your power goes out the slipping wheel - along the path of least resistance. Torque biasing differentials offer increased bias ratios over open differentials. For example, if a diff has a bias ratio of 2.5:1, then it can apply drive torque to the wheel with the most traction (gripping wheel) at 2.5 times the traction limit of the wheel with the least traction (slipping wheel). This is a significant improvement over an open diff… most of the time. The problem is that when one tire has LITTLE or NO grip (zero axle-load), the other wheel gets ZERO DRIVE, because (basic math here): 2.5 x 0 = 0. Lift a wheel (or substantially unload a wheel) and you get zero axle-load on that side - that means that during the time the wheel is unloaded, the typical diff will NOT power the wheel that’s still on the ground. No matter how high the bias ratio, you get no power to the ground. During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over. While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction time in the driveline. The Wavetrac®, however, is different: The innovative, patent-pending, Wavetrac® device in the center of the diff responds during these exact conditions when zero or near-zero axle-load occurs. At or near zero axle-load, the axles (and therefore each side gear in the diff) start to turn at different speeds. This speed differential causes the Wavetrac® device to step into action: Precisely engineered wave profiles are placed on one side gear and its mating preload hub. As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. Very quickly, this creates enough internal load within the Wavetrac® to STOP the zero axle-load condition. The zero axle-load condition is halted, and the drive torque is applied to the wheel on the ground (the gripping wheel)… keeping the power down. Some gear differentials rely solely on preload springs to combat loss of drive. The drawback is that you can’t add enough preload to prevent loss of drive without creating tremendous handling and wear problems at the same time. So, to avoid these problems, the preload from ordinary spring packs must be reduced to a level that renders them ineffective at preventing loss of drive. The Wavetrac® is the only differential that can automatically add more load internally when it’s required. In the case where both wheels are on the ground during zero axle load, such as during a transition to deceleration, the Wavetrac® device is able to prepare the drivetrain for when the zero torque condition stops, eliminating the delay seen with ordinary gear diffs. What this means for you as a driver is that power is delivered to the gripping wheels for more time and in a more constant manner – making you faster and improving stability. The Wavetrac® truly is different - and its innovative features can make a real difference in your car’s performance. Here’s something else you won’t find in any other design: The Wavetrac® diff’s behavior can be altered in the field to suit your needs. It comes standard with carbon-fiber bias plates for the best all around performance and lifetime durability. Changeable plates using materials with different friction coefficients to fine-tune the bias ratio are sold separately. These bias plates provide a mechanism to tune the response of the differential as a function of applied torque load. The applied torque load manifests itself as an axial load from the differential pinions into the housing. This axial force is then considered a normal force into the bias plate, and as a function of the effective coefficient of friction, provide a resistive torque to the rotational motion of the differential pinions. The resistive torque will add to the resistance of relative rotation of all components within the differential. The resistive force, however, is non-uniform since it is a function of the axial load from the differential pinions. The unbalance of the resistive torque will manifest as non-uniform energy absorption within the differential causing a bias ratio. Here are more features that make Wavetrac® even better: The new Wavetrac® Differential brings current gear technology to the market. Internally, its gear tooth forms are optimized for strength and improved oil film retention over competitive designs. Our gear package is smaller, reducing overall mass, yet is more durable since particular attention was paid to the tooth strength - optimized for high torque conditions. Attention was also paid to the side gear/axle interface, putting as much material thickness as possible in this critical area - most important when power levels get high. Each Wavetrac® Differential is crafted from the highest quality materials available. The internal gears are made from high strength 9310 alloy steel. The diff bodies are machined from case-hardened steel billet. To complete the package, every Wavetrac® differential is built exclusively using high quality, high strength fasteners from ARP®, the world leader in fastener technology.
We got that part. That covers #1. #2 was the accel-to-decel-to-accel. When both wheels are firmly planted on the ground and you're going in a straight line. -> no speed differential. Wavetrac does something for that. What?
Dave.... isn't this the explanation you are looking for? WaveTrac As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. Very quickly, this creates enough internal load within the Wavetrac® to STOP the zero axle-load condition. The zero axle-load condition is halted, and the drive torque is applied to the wheel on the ground (the gripping wheel)… keeping the power down. Others... Some gear differentials rely solely on preload springs to combat loss of drive. The drawback is that you can’t add enough preload to prevent loss of drive without creating tremendous handling and wear problems at the same time. So, to avoid these problems, the preload from ordinary spring packs must be reduced to a level that renders them ineffective at preventing loss of drive. The Wavetrac® is the only differential that can automatically add more load internally when it’s required.
Nope. This is what they do for the case of one wheel lifting (zero torque cause one wheel is completely off the ground) This is how they do it. Other gear diffs handle this with some amount of preload. Usually supplied by springs. The downside is handling when you don't want your diff locked. Not much preload and not much power applied to the wheel on the ground. Too much preload and it's always sort of locked -- bad for handling when you don't wnat it. Wavetrac handles this with their "wave" profile...one profile climbs up over the other profile due to the speed difference. The missing explanation (coming soon) is for when both wheels are firmly planted on the ground, like in straight line driving, and a zero torque condition, like when you are transitioning from on the gas to off the gas -- negative effect/lag occurs when getting back on the gas. (I feel like I need a baseball bat here, you're not being a good listener)
:bang: Got ya...no bat necessary. I thought #2 was explained. I assume this is the "Bias Ratio" they discuss. But at least we got the rest fully explained. ..
Flex, Well, here it is as best as I can describe it, When you go in a straight line, with no speed differential..... You do not need a differential!! The wavetrac is ready to act as soon as there is even a minimal speed difference in the wheels. If you are going in a straight line, full grip on both sides, zero speed differential, then everything will act as intended, a diff will almost not be needed, as mentioned above. Heres a portion of the site which describes what happens from accelerating to decelerating, which should answer some questions: During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over. While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction time in the driveline. At or near zero axle-load, the axles (and therefore each side gear in the diff) start to turn at different speeds. This speed differential causes the WavetracR device to step into action: (I think this portion of the info was already up on your thread actually) Precisely engineered wave profiles are placed on one side gear and its mating preload hub. As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. Very quickly, this creates enough internal load within the WavetracR to STOP the zero axle-load condition. The zero axle-load condition is halted, and the drive torque is applied to the wheel on the ground (the gripping wheel). keeping the power down. Some gear differentials rely solely on preload springs to combat loss of drive. The drawback is that you can't add enough preload to prevent loss of drive without creating tremendous handling and wear problems at the same time. So, to avoid these problems, the preload from ordinary spring packs must be reduced to a level that renders them ineffective at preventing loss of drive. The WavetracR is the only differential that can automatically add more load internally when it's required. In the case where both wheels are on the ground during zero axle load, such as during a transition to deceleration, the WavetracR device is able to prepare the drivetrain for when the zero torque condition stops, eliminating the delay seen with ordinary gear diffs. What this means for you as a driver is that power is delivered to the gripping wheels for more time and in a more constant manner - making you faster and improving stability. Flex, I hope that helps a bit, most gear driven diffs are only able to work as intended/designed on acceleration, whereas our unique wave-center hub in our diff allows the Wavetrac to continue 'doing its job' on deceleration or engine braking as well, unlike other gear diffs which need to 'reasess' how best to bias power when a wheel is lifted or encounters a no- or zero-load condition, which causes a lag in how the differential acts on the rest of the drivetrain, which is not ideal. My boss may be able to put this a bit more eloquently when he returns on Monday if this is still not completely clear. Regards, Ryan Vieau
Maybe this is the part... The Wavetrac employs a speed differential mechanism (those wave profiles). and this allows it to react more quickly to one wheel slipping when accelerating after a deceleration? I'm thinking maybe they should have left that part out. "while this condition is generally short-lived"... is that a matter of milliseconds?
No doubt it works. and probably the best out there for our application. (...it's just that I don't understand that acel-decel bit... oh well)
if you really want to get in some light technical reading, just read the patent application for their unit. It gives a full detail explanation of the gearing and torque biasing mechanism in the unit. Easy to find, if not linked directly from their site.
It appears the Wavetrac is very popular in VW, BMW, Jag, MB....etc. Here is a nice 1 year user review from a "laymans" point of view. http://forums.fourtitude.com/showthread.php?4396630 I get it now.. Here is a VERY cool x-ray video of it in operation. http://www.autotech.com/prod_drive_wavetracDiffs.htm ..
The "wave design" allows for a more constant contact betwenn the axles. As you pass from "full float" to "locked" axle motion you are "gripping or tarnsfering torque to the axles sooner than using a traditional gear mesh which has to "fall into place".. As to the 2 "wave design contacts" pass over each other they are gripping sooner due to the "slope" in the wave (longer angle). A gear has a lot less "slope", so more travel time and "clunk". I bleieve the slope is adjustable by different "wave packs". And this time frame between full torqu (or foll contact of the "waves") is very short...probably milliseconds yes. Am I right here? It is amazing watching that video and seeing hoe the gearing is meshed to transfer power....all those outside "Helical" gears that are used on the outside to transfer power.
