POSITRACTIONS / LIMITED SLIPS

Auburn Gear (AG)
The Auburn Gear limited slip uses a cone style clutch that wears directly against the carrier case and provides the friction force to make the unit work. This design is not rebuild-able. Once the cone clutch or case wears out, the entire unit must be replaced. Even with this shortcoming, this design works well for occasional use where extra traction is needed. They have good impact strength in passenger cars and trucks up to 1 ton. They will hold up well to high horse power, but will not last long if there is a lot of tire spinning. (after market ) 1 yr warranty

Auburn Gear PRO (AG)
Also cone style & not rebuild-able. Designed with more lockup force than regular Auburn Gear limited slips. Will provide better high performance traction than regular Auburn Gear, but still wears out under extreme off-road use and heavy wheel spin. This design tends to chatter a lot and is not recommended if the customer is looking for a smooth unit. (aftermarket ) 1 yr warranty

Detroit Locker (DET)
Heavy duty. Probably the most durable design available, the king of traction differentials. Usually causes banging and clunking, but gives 100% lock-up whenever traction is needed. Unlocks when negotiating a turn so that the outer wheel can turn faster than the ring gear is turning and the inside wheel are turning. Does not need any interaction from the driver. New Sof-Locker design has damping device to reduce banging and clunking. Includes carrier case that is stronger than stock except in 2 applications where the original factory carrier case is used. Only the 10.5" 14 bolt truck and the Nissan V6 designs use the factory carrier case and these cases are both very strong. (aftermarket ) 1 yr warranty

Eaton (EAT)
Clutch type, similar to Trac-Lok in design, yet far stronger like a Power-Lok, and, more aggressive and better lock-up similar to the Power-Lok design. These units came as an original equipment option in 65-72 12T (12 bolt GM truck), 12P (12 bolt GM passenger), 8.2" GM pass, 63-79 Cast Iron Corvettes. The original OEM 12T case was very weak, but the new design replacement from Eaton is very strong. 4 preload springs and 2 steel preload spring plates. Latest design uses HD nodular iron case, forged side and pinion gears, no-chatter, race-bred, carbon fiber clutches for extreme strength and longevity. Old design, all steel clutches which are still available in 18 or 22 clutch designs for those who need more lock-up and are not bothered by clutch chatter. For even more lockup customization, there are also 4 levels of spring pressure available (3 from Eaton and a fourth from GM) that can be used to vary the clutch preload from 200 lbs. to 800 lbs. Originally used in mid sixties GM muscle cars and trucks. This unit is now available for Ford applications and soon will be available for Dana Spicer, AMC, and Chrysler applications. They have a high tolerance for abuse in high horsepower vehicles. Recommended for everyday driving and severe off-road use (factory GM )

Equal-Lock
This was the first design limited slip used by Ford in both the 8" and 9" rearends. Except for new clutches, there are only used parts available now. This design is not aggressive and does not lock-up harder when more power is applied as most every other limited slip design does. Ford built two different Equal-lock designs. One uses 4 plain steel plates, three fiber lined plates, and one Belleville spring for preload. The other uses only 3 plain steel plates, 2 fiber lined plates, and 2 Belleville spring plates. The design that uses two spring plates can only be converted to the single spring design with more clutches if the appropriate clutch hub is used to accommodate the higher number of clutch plates. Can be identified by 5 tab clutches (Ford Traction-Lock for the 8" and 9" use 4 tab clutches) (factory )

Traction-Lock (T/L)
(Also referred to as a Track-Lock, not to be mistaken with the Dana Spicer Trac-Lok) This is the second design limited slip that Ford used in both the 8" and 9" rear-end designs. It is a fairly good design for moderate horsepower applications. This is a clutch type design that uses 4 plain steel clutches, 4 fiber lined clutches, and 1 plate that is steel on one side and has fiber lining on the other side. It uses a two piece case that looks very similar to the standard open carriers, except the parting line between the two case halves is covered by the left half that "wraps around" the right half. The parting line between the two halves on a standard case is easy to see and is not covered. Traction-Locks are not very aggressive and tend to wear out fairly quickly if used heavily.

Newer design Ford rear-ends such as the 7.5", 8.8", 9.75", 10.25", and 10.5" also can be ordered with Traction-Locks. These differentials use a one-piece case with two spider pinion gears, except for the heavy-duty 10.5" rear-end, which uses three spider pinion gears. The 7.5" and 8.8" designs have soft clutches that tend to wear-out quickly and are not aggressive even when new. The 10.25" unit uses composite clutches that holdup fairly well, but it is not aggressive and tends to slip too much when needed off-road. Trac-Lok is a medium-duty limited slip and will hold up without breaking, but will wear-out the clutches quickly under heavy-duty use. If the unit wears out it usually can be rebuilt. (factory )

Trac-Lok (T/L)
Built by Dana Spicer for use in Spicer rear-ends, AMC rear-ends, and 1998 & older 10.25" Ford rear-ends. The old design built up until about 1989 was weak. The 1990 and newer design is fairly strong and even rivals the Power-Lok for impact durability, but the clutches do not provide as much lock-up force and tend to wear out in about 50,000 miles if used in the rear. Works better in the front of vehicles because it's not aggressive. The main selling points for this design are the fact that clutch chatter is almost non-existent, and it is very inexpensive. These two points make it a great unit for many applications and a very good value for the money. This unit makes a great front limited slip and works well for those who need a little extra traction but cannot tolerate clutch chatter. The Trac-Lok came factory installed in many models such as D28, D44, D60, AMC 20, AMC35, 10.25" Ford. The problem with this unit is that it is not very aggressive and power transfer is minimal. Also, 1988 and earlier units tend to break fairly easily. (1piece case, 2 pinion gears, and 2 tab clutches). (factory )

Powr-Lok (P/L)
This clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Power-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Powr-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory)

Toyota Race Development (TRD)
This is a really good Toyota differential. They operate on the same principal as the Powr-Lok. The clutches virtually never wear out. Sometimes this unit chatters and sometimes it does not, depending on the specifications requested by the importer. They are sometimes imported in small quantities by various sources and are now distributed by Auburn Gear. (after market ) 1 yr warranty

Truetrac (TT)
Based on the worm gear principal and works like clutch type posi-traction. Does not wear out, not recommended for tall tires over 33".

Detroit True-tracs are similar in design to the Gleason Torsen®, only the True-tracs hold up well with reasonably tall tires. They use worm wheel gears that work on the same principle as a worm gear. When the unit is loaded, the worm wheels are forced away from each other and against the case. They develop locking torque by the light friction between the worm wheels and the case. This light friction is multiplied by the ratio of the worm wheel which depends on the size of the worm wheel relative to the size of the side gear. The manufacturer can change the amount of torque biasing or lockup by simply changing the diameter of the gears, or the pitch and spiral of the teeth. A larger difference in the size for the worm wheels and side gears (smaller worm wheels and larger side gears) will increase the lockup force. Increasing the pitch and spiral of the teeth will also increase the lockup forces. Like everything, there is a limit as to how much lockup force is reasonable. Making the unit too "aggressive" will cause tire scrub during everyday driving and will cause the unit to wear out too quickly. All of the feedback that I have received from customers indicates that the unit works very well for mud and snow, while going unnoticed during every day driving. When used in situations like rocky trails where one wheel gets off the ground, the unit will not lock up 100%. Light application of the brakes will help the differential engage more transferring power to the tire that is still on the ground. For extreme situations where the vehicle will have one wheel in the air often a locking differential provides better power transfer to the wheel on the ground.

Detroit Truetracs are designed for medium duty 2WD and 4WD applications. They work well in the front and rear, and are so smooth that there is little or no hint of resistance in the steering wheel when used in front drive steering axles. Like the Gleason Torsen®, the Detroit True-trac does not bang or clunk, has no clutch chatter, does not wear out like clutch type posi-tractions, does not need limited slip additive, and needs no preload or clearance adjustments.

Almost sounds too good to be true doesn't it? The only drawbacks to the True-tracs are their inability to provide lockup 100% like a locking differential can. Although Gleason no longer makes the Torsen® differential, the Detroit True-trac is a proven design that is available for many popular applications. (aftermarket) 1 yr warranty

Gleason Torsen
Worm gear type no longer made by Gleason, but a few models are build by Zexel Torsen. They are very similar to the Truetrac. (aftermarket)

Gold Trac
9" Ford road racing and circle track. Very similar to the True-trac, but a lot more expensive. The preload on the worm wheels can be adjusted on a Gold Trac, but they do tend to loosen up after some time. (after-market)

PASSIVE LOCKERS

Gov-lock(G/L)
Used by General Motors in 73 & newer trucks that came with an option locking / limited slip differential. It was used in 7.5", 7.625", 8.5", 8.6", 8.875" 12 bolt truck, 9.5", 10.5", and now in the new 11.5" differentials. The smaller designs are fairly weak and the 8.5" and 12 bolt truck designs are especially weak. The 9.5" and 10.5" 14T units are fairly strong and will hold up well to towing and moderate abuse. The Gov-Lock is designed to act as an open differential during normal driving with no force being applied to clutches. This fact that no force is applied to the clutches keeps the clutches from chattering during normal every day driving. When either wheel slips and spins approximately 100 rpm faster than the other a governor assembly senses the difference in speed and activates a ramp system. The ramp system causes the clutches to engage and transfer power to the wheel with traction. One other feature of the Gov-Lock is that it will not engage at vehicle speed above 30 mph. This no lock-up feature keeps the vehicle more stable at higher speeds where both wheels spinning could cause an inexperienced driver to spin out or slide off of the road. This is a great design in theory and works as designed in a stock vehicle that is not abused. The problem is that most of us modify our trucks and many of us abuse them. When this unit is asked to deliver under extreme conditions it tends to self-destruct. The force generated by the ramp system that is used to lock-up the clutches works well, except that same force has to be contained by the case and the case is not always up to the job. (factory)

Lock-Right (LR)(PT)
Mechanical locking mechanism that installs into the stock carrier case in place of the spider and side gears. This is a very low price unit that is fairly easy for the average vehicle owner to install if they are somewhat mechanically inclined. This unit was originally designed by Power-Trax and is still produced by them. It has also been copied by Tractech in the form of an "Easy Locker". Works great for occasional off roaders, or for use in front differentials. This is a mechanical locking device that drives with the same results to the wheels as a Detroit Locker, but uses the standard carrier case and cross pin and does not include any parts to dampen the banging and clunking associated with a locking differential. Provides 100% lockup when traction is needed. The re-use of the original carrier case keeps the cost down but, offers no more strength than the stock carrier case. Power-Trax offers a heavy duty "Zytanium" (this is only a brand name for the material they choose not to disclose, not an actual material that can be looked up in a metallurgy book) cross-pin shaft that lasts longer than the stock cross-pin and is often necessary for differentials in which the stock cross-pin is too soft for use with the Lock-Right. Most Lock-Right designs come with enough parts to replace all of the internal side and pinion gears. A few of the Lock-Right designs use the stock side gears which are used in conjunction with the new parts. These units include the 8" & 9" Ford, D70's with 2-piece case, and the Suzuki Samurai. It should be noted that the units for the Samurai are available either with parts (couplers) to replace the side gears, or as a design that uses the original side gears (without couplers). The design that uses the stock side gears actually seems to hold up better and last longer than the design that replaces the side gears. Many of the Lock-Rights built by Powertrax have been improved since the release of Tractech's Easy Locker and the Easy Lockers have not. (after-market) 2 yr warranty

Heavy Duty Lock-Right (VX models) (LR) (PT)
These units drive the same as a regular Lock-Right, but include heavier springs, better materials, and the Zytanium cross shaft. In fact, the entire unit is built from the material they call Zytanium and is designed for a lot of abuse in applications such as drag racing or extreme off-road use. This unit does not have any dampening mechanism and tends to do a lot of banging and clunking when driven on the street.

EZ Locker(EZ)
Built the same as a Lock-Right with all of the same characteristics, features, benefits, and shortcomings, but only has a 1-year warranty. Fits into stock carrier case. Designed for occasional off roader. SEE Lock-Right for MORE DETAILS.(aftermarket) 1 yr warranty

Gearless Locker (GL)
The overall results of the Gearless Locker are that its operation is the same as the Detroit Locker without the extra backlash. The unit drives both tires unless the vehicle is negotiating a turn, in which case it allows the outside wheel speed to override the inside wheel speed so that the tires do not have to scuff, or be dragged around the turn. The free-wheeling side re-engages and drives again as soon as the inside tire speed catches back up with the freewheeling side when the vehicle completes a turn, or the inside tire spins and reaches the same speed as the outside tire. The only side effects are strange handling in short wheel-base vehicles while negotiating sharp turns under power, and the spinning of the inside tire while taking off from a stop sign, while turning, when the road is slippery. And the obvious question is "how does it do that?" The whole key to the operation of the Gearless Locker is the "Tunkenel-V" ramp. (is this a goofy name or what?) The force of the cross pin shaft on the Tunkenel V ramp produces a separating force between the cross pin shaft and the V ramp as the shaft attempts to ride up the ramp. This separating force on the V ramp causes a clamping force on the friction clutches, which locks the side gear to the case as the clutches engage and drives the axle, which drive the wheel. If any force causes the wheel to go faster than the ring gear that is driving it, the results of the overriding speed of the wheel will cause the force on the V ramp to decrease, and the clutches will disengage allowing the overriding wheel to free-wheel until the overriding force causing the wheel to turn faster than the ring gear is gone (when the vehicle completes the turn). This may seem complex, but read it through a few times and then give it a few days to sink in before reading it again. The idea of clutches may bring up concerns of chatter or wear. Unlike clutches in most applications, these clutches lock instantaneously and do not slip at all (which makes the unit work without the extra backlash associated with other lockers). They also release instantly when any overriding forces are created while negotiating a turn. This instant release design does not allow for any chatter whatsoever. Additionally, Trac-Tech states that in all of their extensive testing they have had no indication of clutch wear, and in fact, they provide a bottle of special additive to keep the clutch surfaces from galling due to the excellent loading of the friction clutches.

Installation of the Gearless Locker is pretty easy and straight forward. Most backyard mechanics will be able to install the unit on a long afternoon or at worst, over the weekend. Some models require removing the ring gear from the carrier, but none of them require any shimming. Like the EZ Locker from Trac-Tech, and the Lock-right from Powertrax, the Gearless Locker simply replaces the standard spider gears in a non-locking differential and works with the stock carrier case and the stock c-clips.

These will work well in both the front and the rear just like other lockers. I know that a lot of readers are reluctant to try a locker in the front. I have driven vehicles with front lockers and find them to be fairly well mannered. I believe that the few small changes in handling are worth the gain in traction, and using a locker will allow the unlocking of one hub for better steering during steep off-camber maneuvers. The details may seem complicated at first, but read them a few times and give the information a few days to sink in before reading it again.

Lock-Right No-Slip (PT)
This design is very similar to the regular Lock-Right, but incorporates a dampening mechanism that keeps noise and clunking to a minimum. The dampening assembly also works as a holdout ring that helps the teeth last longer and makes disengagement and freewheeling around a corner smoother and quieter.