Jan 052012

O.S. Giken is now shipping the OS Super Lock LSD (CH061-HA) for 2010 and 2011 218mm Camaro V8 differential. The Super Lock weighs in at 30 pounds.

The OS Super Lock’s race proven design provides extreme durability, legendary reliability, and outstanding performance while still offering a comfortable driving experience.

UNITRAX 800.622.4327

Dec 122011

The Getrag H226 found in the 2009 – 2011 Dodge Challenger. This assembly is equipped 3.73 ratio gear set and a stock limited-slip differential. The unit  is also available in 3.06 and 3.92 ratios.

Dodge and Chrysler M210 (5.7) and M215 (6.1 Hemi) owners can upgrade to the H226 differential!

Getrag H226 3-73  004Getrag H226 3-73  008

Call UNITRAX at 800.622.4327 for more details.

Oct 192009


Eaton Detroit Truetrac for the 2009 Pontiac G8

The Detroit Truetrac was the first helical gear differential ever introduced into the automotive aftermarket as an Eaton brand. It remains the leading helical gear-type limited slip differential in the industry. Detroit Truetrac’s proven helical gear design eliminates the need for wearable parts, resulting in maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well.

Proven design and effective performance all make the Detroit Truetrac limited slip differential the ideal choice for a wide variety of vehicle applications. No maintenance –   Just Traction.

  • Smooth Operation
  • Performs Open Untill Needed
  • Fully Automatic Limited Slip
  • No Special Lubrication Required
  • No Special Run In Procedure Required
  • Billet Steel Heat Treated Body and Caps
  • Forged Heat Treated Shot Peened Internal Gears

UNITRAX 800.622.4327

Sep 242009

The BMW Wavetrac® is designed for the 335i, 540i, E39, and Z8 cars. Special machining is required for this application. Contact UNITRAX for specific details.

Wavetrac BMW  007

The M215 Wavetrac® is designed specifically for the Mercedes E55 AMG, and Chrysler’s 6.1L Hemi SRT Dodge Challenger, Dodge Magnum, Dodge Charger and Chryser 300. The unit has been engineered to allow for better lubrication in the side gear area.

Wavetrac M215  011

Wavetrac®: Designed from a clean sheet using state-of-the-art knowledge and engineering to be a better differential than any other. It uses a patent pending design to improve grip in low traction conditions.

Wavetrac®: Gives you quicker acceleration and faster cornering by driving both drive wheels instead of just one. And, it offers improved no-load performance when compared to other helical gear differentials on the market.

• 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 all gear diffs except Wavetrac® 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.

Sep 242009

Eaton Performance is now shipping the Detroit Truetrac for the Corvette C4 Dana 44ICA differential.


This unit offers a great value to those Corvette owners who want a LSD that is significantly stronger than stock but without the expense of the pure race LSD’s like the O.S. Giken Super Lock.

The Detroit TrueTrac is the first helical gear differential ever introduced into the automotive aftermarket as an Eaton brand. It remains the leading helical gear-type limited slip differential in the industry. Detroit Truetrac’s proven helical gear design eliminates the need for wearable parts, resulting in maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well.

Aug 252009

The following (below the posts) is a response from O.S. Giken regarding the Super Lock that generated from the Viper Club forums:


Thank you for letting us know about some confusion arising on the internet regarding our OS Super Lock LSD for the Gen 3 Viper.

I will try to provide an explanation to the following postings that contain some comments that may be misleading when applied to

the OS unit:

The Posts:

Quote #1

I am sure they are a fantastic piece of gear, the stuff they make for Skylines is impressive too.

However to throw out a quaife for one on a street car or a road race car I would question – unless you want to drift.

The fundamental difference is that the quaife is not a true LSD – it applies power to both wheels in a straight line, but to the side that needs it most when traction is lost. It is this function that enables more power out of turns because it is applying more power to the OUTSIDE wheel which means to you get power down and can steer the car.

By comparison, once traction is lost with a locked diff (OS Giken under power) you cannot steer a locked diff car on steering wheel input alone eg. out of a corner or when the back flicks out! You have to steer LSD cars with the throttle as well once they lose traction. This is perfect for drifting, great for drag racing (until the car goes sideways) but terribly unsafe on public roads unless you have the feel and skill to match.

For super high powered cars I would be keeping the quaife – much safer – but then I’m past needing to powerslide at 125mph steering on the throttle yelling “yee haa yahoo!”

Still, for LSD applications – I’d bet this OS Giken will be better than anything else.

Quote #2

Originally Posted by gb66gth

In reading the devolpment info, provided earlier in the thread, something was mentioned about how the OS Giken dif. would reduce understeer on entry into slow corners on a road course (not a direct quote). Can someone explain to me how this works, that is the dif having an efffect on the front end of the car? I’m no mechanical engineer so a little help here, please….

Reduced corner entry understeer is not a characteristic of clutch-type limited slip differentials vs. the stock Viper units or a Quaife/torsen. It’ll make it worse. A 1.5-way won’t be as bad as a 2-way or spool though – the “original torque setting” (quote from below) is still greater than zero.

Here’s why- when a car is going straight, all 4 wheels are turning at the same speed. In a corner, the inside wheels are turning slower than the outside wheels. In order to initiate a turn, the outside wheels have to speed up vs. the inside. A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels – EVEN WITH THE THROTTLE CLOSED. An open diff doesn’t do this, nor do the stock viscous units or a helical diff like the Quaife. This resistance makes it more work for the front tires to rotate the car, hence more entry understeer.

All this isn’t necessarily the end of the world, some people like the extra “stability” while trail-braking into a corner. If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I’d choose.

The O.S. Giken Response: The OS Super Lock LSD Spec-S settings allow for a smooth and progressive ramp up in lock all the way to 100% lock. The OS Super Lock is unlike other traditional clutch type differentials in that the unique design allows for almost twice the number of clutch plates. More clutch disks provide more surface area to create more friction, necessary to provide the limited slip effect as well as full lock. Having more clutch plates also means that we can achieve up to 100% lock while using minimal preload on the clutch disks. This preload is what provides the “lock” people refer to when one wheel is off the ground. The preload for the OS Spec-S units is set more to supply added stability, rather than full “one-wheel performance”. The preload is mild enough that it will feel very similar to a stock open differential to the daily driver, until the torque is applied. From that point, the unit will provide a smooth and progressive lock up (in direct relation to amount of torque applied, of course) and keep the vehicle moving forward.  The Spec-S units utilize a 1.5way cam angle, meaning that the ramp-up to lock will be bias to providing a more positive lock up on acceleration and far less on deceleration, where the ramp to lock-up will serve more to stabilize the vehicle during braking/deceleration. In essence, the Spec-S will feel like an open differential that doesn’t allow for unwanted wheel spin when exiting corners or “tail wagging” during heavy straight line accelerating (as the unit will provide progressive locking at equal rates to both wheels due to the centered design of our unit). For drag users, this will translate to greater straight line acceleration and keep the rear where it is supposed to be. For track/autocross users this translates to faster corner exit speeds (progressive lock allows for earlier application of throttle) and more stability during heavy braking. In addition, due to the minimum amount of preload utilized, corner entry is essentially unaffected. Faster times will be achieved.

Both of the above comments posted from users in the forum are not necessarily incorrect, but they are not very applicable to the OS Super Lock, as it is very different from traditional clutch type LSDs.

Both situations seem to be describing the turning characteristics and controls of an OS Super Lock LSD as that of a spool or welded differential, or one of our units specifically tuned for drift (higher preload, faster lock timing, etc…). I hope that with the above explanation, your inquiring customers will understand that this is clearly not the case with the Spec-S settings.

While the above explanation mostly addresses the OS Super Lock’s locking characteristics, it should be mentioned that it also unlocks in a relatively seamless fashion. This is due to the design of our pressure ring, which forms the basis of our lock timing control system. In the scenario you mentioned of a customer potentially loosing tire traction and control due to premature lock (likely due to an over-application of torque vs. capacity of the tires when trying to make a turn at an unfavorable angle), if the customer simple lifted off the throttle or up-shifted (thus lessening the application of torque to the wheels/differential) the differential would unlock and allow for the vehicle to regain control via steering and throttle input. Granted, we do not advise any users to practice this on the street!

If any of your customers or Viper owners have any questions regarding our unit, please feel free to forward their questions over to me or have them contact us via our website at www.osgiken.net. We are always happy to spend time with customers and will answer any questions they may have.

Thank you.

Jul 062008

Four Limited-Slip Differentials For The Viper SRT 10

Positraction For Street, Strip and Track

The ‘Gen III” Dodge Viper SRT 10 was introduced in 2003 with fresher look, more power, and a new version of the Dana’s resilient 44 differential, the M44-4. Along with a new housing, the M44-4 was fitted with Dana’s Hydra-Lok limited-slip differential.

2008 Dodge Viper

Because the 2003 M44-4 housing was designed to accept the Dana Spicer Hydra-Lok, the Viper community was initially left with no positraction alternatives. However, today the SRT 10 owner has four limited-slip differentials to chose from. Two of the units are engineered to meet the most demanding performance applications and a third is found in the 2008 “Gen IV” Viper SRT 10.

Dana Spicer Hydra-Lok

Dana’s Hydra-Lok was originally developed by ASHA Corporation in Santa Barbara. McLaren Performance acquired ASHA and sold the rights of ASHA’s Gerodisc technology to Dana’s Spicer light duty axle division. Dana completed development of the unit and trademarked the LSD as the Hydra-Lok. Production began in Syracuse Indiana and in 1999, Jeep debuted the Hydra-Lok in the Grand Cherokee.

Gerodisc technology is speed and torque sensitive, operates full-time, and offers proportional torque transfer with progressive action. It uses the differential oil to operate the Gerotor. TwinDiscs provide one coupling per wheel. The fluid is released at calibrated pressures to engage the clutch pack.

The Hydra-Lok transfers wheel torque as conditions demand, ensuring improved traction and handling. Unlike traditional disc-based LSD’s, the Hydra-Lok offers controlled torque transfer. It does not waste power on wheel spin, rather it transfers torque to the wheel with the most traction. The torque is independent of the slipping wheel condition. The Hydra-Lok is speed-sensing meaning that the torque transfer is independent of the slipping wheel’s traction. The amount of torque transferred to the wheel with traction is based on the speed of the spinning wheel. Resulting in nearly immediate transfer of torque from the wheels that slip to those that grip.

According to Dana Corporation, when a Hydra-Lok equipped Viper begins to negotiate a curve, the vehicle reacts as if it had an open differential to reduce the potential of over-steer. As the vehicle continues through the corner, it takes on the characteristics of a limited-slip differential, transferring torque to the wheel with traction. Coming out of the curve, however, the Hydra-Lok allows the Viper to deliver the maximum amount of torque to the ground for improved speed while exiting.

The 2003 version of the Hydra-Lok had an issue with the cross pins breaking. UNITRAX developed a replacement 300m cross pin to prevent Hydra-Lok failures. In 2004, Dana upgraded the Hydra-Lok with a heat-treated cross pin. Side gear and pinion gear failures have continued to plague the SRT 10 owners.

Unfortunately, dependability and durability issues have spoiled the promise of the M44-4 Hydra-Lok.

Quaife ATB Differential

The first manufacturer to supply a replacement for the stock SRT 10 Hydra-Lok was R.T. Quaife Engineering Ltd. The Quaife ATB differential was developed in the 1980s and is used throughout world.

The characteristics of the Quiafe is that it progressively locks as torque increases; there are no plates or clutches to wear out. By getting the power to the ground, the Quaife enables the Viper to accelerate quicker and corner faster.


The Quaife is an automatic helical-gear based differential. Sets of floating helical gear pinions mesh to provide the normal speed differential action. To pre-load the gear packs there is a selection of centre spring discs available. In the event of wheel-slip, torque bias is generated by the axial and radial thrusts of the pinions in the pockets. The resultant friction force enables the driving road wheel and sun-gear to transmit a greater proportion of the torque. The effect is progressive, but at no stage does the Quaife lock solid.

The Quiafe ATB Differential powers both drive wheels under nearly all conditions. The differential senses which wheel has the better grip and automatically biases the power to that wheel. The transition of power is smooth and constant without ever completely removing power from the other wheel.

In drag racing, the Quaife provides straight-line acceleration that is close to an ideal 50/50 power split to both drive wheels.

In cornering, while accelerating out of a turn, the Quaife biases greater power to the outside wheel, reducing inside-wheel spin. This allows you to begin accelerating earlier, exiting the corner at a higher speed.

The Quiafe differential also controls loss of traction when the drive wheels are on slippery surfaces by providing the appropriate biased traction needed to overcome these adverse conditions.

The Quiafe’s distinctive design offers maximum traction, improves handling and steering, and applies the power where it is needed most.


To install a Quaife ATB into the SRT 10 differential, the stub axles must be drilled so that bolts can anchor them in.

In order to maximize the performance of the Quaife ATB differential, the suspension should be set up like an open differential; stiff springs and a soft sway bar.

The Quaife is exceptionally strong and requires no maintenance. 

Quaife UK does not offer a warranty on their products sold in the U.S.A. Check with your installer or dealer on the latest Quaife USA warranty details.

OS Super Lock LSD

OS Giken Co. Ltd. of Japan has recently introduced its highly respected and race proven OS Super Lock LSD. The Super Lock was in development for four years before its initial release.

The OS Giken Super Lock LSD is more closely related to the disc-based TracLok LSD found in the Dodge Viper from 1992 through 2002. However, that is where the comparison ends. The revolutionary Super Lock is a true 100% locking LSD that instantly reacts and transitions smoothly from both free and locked positions, combining open differential drivability and limited slip differential performance and stability.


The OS Giken Super Lock features innovative technologies like the adjustable lock timing adjuster. Lock timing can be adjusted by replacing the springs in the pressure ring. Initial torque settings also adjustable through cone springs located at ends of clutch stacks. This allows the Super Lock to be tuned to meet your exact needs for optimum performance.  UNITRAX is an authorized tune center and can discuss tuning for a variety of environments.

OS Giken is committed to producing an extreme quality LSD. Every Super Lock is manufactured from only the finest materials, regardless of the production cost. The Super Lock housing is manufactured from a proprietary billet steel alloy which is then heat-treated when finished. The gears are all hot forged. This attention to detail improves the precision and performance of the product.

U.S. patented bevel gear-in-pressure ring mechanism has enabled OS Giken engineers to miniaturize each gear, thus providing more space for up to an unprecedented number (28) of all-steel friction plates. The Increased number of friction plates improves the locking force of the LSD enabling it to lock fully and completely. An added benefit to being a fully locking mechanism is that less heat is generated, thus resulting in incredibly higher durability and reliability in even in the toughest racing environments.

OS Giken states that they have tested the Super Lock for over 22,000 performance miles and upon inspection of the unit, there was no wear, no loss of initial torque, and no loss of performance. UNITRAX has inspected a Super Lock that was run in three race seasons. The unit showed no signs of wear and many of the components looked as if they had just come out of production.

The higher locking force provides excellent straight-line stability at the drag strip. The Super Lock will lock 100% and transfer torque equally to each wheel.

You will experience less under-steer during cornering. When entering a corner with the throttle closed, the spring inside the pressure control ring will react accordingly and immediately return the Super Lock to its original torque settings. When exiting a corner, the Super Lock’s transition to the 100% locked position is smooth and predictable, resulting in better traction, stability and quicker exit speeds.

One key feature separating the Super Lock from our other clutch type LSD’s is that with the Spec-S (standard) settings, the Super Lock is actually able to function as a open differential at low speed/low torque situations. Thus, when performing a normal slow speed turn (such as a right hand turn on the street) or backing out of a parking space, our differential functions as a normal open differential, allowing smooth turning without premature wheel lock. Of course with performance settings, such as drift which would require a much higher setting of initial torque, some premature locking may occur.


The Super Lock does not require that the stub axles be drilled. The OS Giken engineers designed the unit to be center-weighted. The unit comes with a new long stub axle so both stub axles will be the same length. It is recommended to use O.S. Giken’s or Schaeffer’s 80w250, or Synergyn Syngear II.

The Super Lock is used competitively in the U.S.A., Europe, U.A.E., Japan, Greece, and Australia. It also has a large following in the drifting community.

The OS Giken Super Lock meets the needs of the demanding driver who is comfortable with the way his SRT 10 feels with the stock Hydra-Lok or Visco-Lok but wants the tuneability, dependability, and durability that a fully race-engineered and manufactured LSD offers. The Super Lock may quickly become the preferred choice in the Viper race community


GKN Visco-Lok

The 2008 “Gen IV” Viper SRT 10 is equipped with the GKN Visco-Lok. The Visco-Lok has been in production since 1999 and is a standard feature in the BMW M3.

The Visco-Lok is a unique hermetically sealed speed-sensing limited-slip differential. The unit benefits through its high-torque progressive locking characteristics which provides maximum torque transfer in excess of skid torque.


The Visco-Lok operates through a self-contained silicone-fluid filled reservoir and shear pump that actuates a wet friction clutch pack. The pump generates pressure proportional to the speed difference between the wheels. The clutch pack actuates thereby transmitting torque to the appropriate wheel. The locking effect increases with the speed difference across the drive wheels.

This locking characteristic enables the Viper to accelerate well on surfaces with different friction conditions between the drive wheels. Additionally, GKN states that the Visco-Lok allows even better acceleration and less under-steer in cornering than compared to torque-sensing LSDs.

UNITRAX has installed several Visco-Lok LSD’s in competition Vipers and to date, the units have proven to be especially reliable and in our opinion, a substantial upgrade over the Hydra-Lok. The Visco-Lok offers the SRT 10 owner improved limited-slip performance at a very reasonable price.

If you have any questions regarding limited-slip SRT 10 differentials, please contact UNITRAX at 800.622.4327.

Copyright © 2008 UNITRAX Drivetrain, Inc.

Nov 072007

OS Giken’s revolutionary Super Lock race limited slip differential is now available for the Dodge Viper SRT 10! The OS Super Lock reacts and transitions smoothly from both free and locked positions. Under normal diving conditions the Super Lock operates with the smoothness of a normal differential. Once power is applied, the Super Lock becomes a 100% locking differential. The transition is so subtle that the driver may not even notice the transition. The OS Giken Super Lock LSD’s offer unparalleled durability and longevity.

OS Giken is recognized as a world-wide leader in race quality engineering.