Frequently Asked Questions: Detroit Locker

• Most gear oils are sufficient: a quality, petroleum-mineral based oil is recommended. 
• Synthetic oils and friction modifiers can also be used, but are not necessary.

There are a few units which require non-OE carrier bearings to be used. These are indicated in the Eaton Performance Application Guide, or you can call the Eaton Performance customer service team. 

Eaton Performance differentials (including Eaton ELocker, Eaton ELocker4, Eaton Posi, Detroit Truetrac, and Detroit Locker) are warranted for one year against manufacturer defects. Download the full warranty document.

 

The Detroit Locker does not require any special break-in process. 

The Detroit Locker is an automatic locking differential. This means it is normally locked during straight-line driving and sends 100% of the available torque to both wheels equally. During turns and maneuvers, the internal components unlock to allow one wheel to spin faster or slower as necessary (free wheel). When the vehicle returns to straight-line driving, the components re-engage and provide equal power to both wheels. 

This happens because Eaton Detroit Lockers have “backlash” or “slack” between the drive and driven teeth and you will hear this in everyday use going through corners and when transitioning from drive to coast. Also, with the vehicle on the ground and the transmission in neutral, several degrees of lash in the driveshaft is normal. Here is a formula to calculate the degrees of rotation of the driveshaft: (differential internal lash X ring and pinion ratio) + ring and pinion backlash + driveline slop such as U-joints wear. 

While many people do use the Detroit Locker during everyday street use, the Detroit Locker is a very aggressive traction aiding differential, initially developed for off-highway, heavy-duty applications. Eaton also makes many applications for on-highway, heavy-duty trucks.

In the 1960’s, the Detroit Locker became a factory option in some Detroit based OEM muscle cars. While most drivers of street cars will find the aggressive engagement of the Detroit Locker objectionable, drag racers enjoy the auto-locking functionality the differential delivers. The Detroit Locker allows drag racing vehicles to differentiate when turning corners, while offering strength comparable to a full spool.

Detroit Lockers have a very high “strength density”, thanks to continual process innovation, advanced metallurgy, and ultramodern machining methods. All Detroit Locker designs are intended to handle more torque (power) than the axle shafts they drive. Horsepower has no influence on the differential. Most Detroit Locker failures are the result of axle shaft breakage causing reaction energy to “back-drive” the internals at a high rate of rotation speed.

The more relevant concern is how much torque each axle shaft can transmit. Fully locking differentials deliver up to 100% of the driveline torque through a single axle shaft. Open, limited-slip, and non-fully locking differentials transmit less torque – often in the range of 50-70%. This is an important point when upgrading a vehicle from a “standard” differential to a fully locking differential such as a Detroit Locker. 

The simple answer is “yes”; however, conditions do apply. If used on-road, selectable locking hubs (not “autolocking”) must be present on the front axle. A vehicle with a locked front differential is not only unsafe to use on an improved road, it will also cause substantial damage to the vehicle and create extreme difficulty steering. The locking hubs must be in their “open” position for on-road use. For vehicles which only operate off-road, the use of selectable locking hubs is optional based on the operator ’s preference and driveline / steering system strength. For off-road vehicles such as rock buggies, monster trucks, and heavy equipment, the use of a Detroit Locker offers incredible traction enhancements. The use of either full-hydraulic or hydraulic assist steering is common in vehicles using an auto-locking differential in the front axle. 

“Soft Locker” versions of the Eaton Detroit Locker / NoSPIN products were introduced in the market several years ago, but not on all models. The function of the Soft Locker is to use a spring generated preload between the side gears of the differential to generate a rotational resistance (dampening). The purpose is to dampen the reengagement action of the Detroit Locker, enhancing the drive feel when used on highway. This preload will cause the units to “feel” as if they have reduced internal lash due to the resistance to rotate, but preload does not influence actual lash.

The internal Belleville style springs and wear disks used in the Soft Locker designs are not required for proper function of the differential. Soft Locker models are identified by the inclusion of "SL" in the model number. For example, 225SL58C. 

Original equipment Detroit Locker and NoSPIN products can be easily repaired. Repair kits for “aftermarket” part numbers are not currently offered. Should you need to repair parts for a Detroit Locker or NoSPIN, they can be purchased from approved service centers for your vehicle. Assistance for locating a retail / service location for repair components is available through the Eaton Performance customer service hotline or on our website. 

Yes, but the operation of the differential will become much harsher and the differential's life may be decreased.

Theoretically, they could; but it is so extremely rare that you should not suspect a spring problem. Typically, only full-race conditions would be sensitive enough to notice any reduced force from the springs. 

Absolutely not. The markings are used to indicate batch lots and production dates. Historically, some retailers have painted the springs, but there is no difference in the springs. 

No. While there are several companies making automatic locking type differentials in the market, none of them have the 80+ years of product development history and manufacturing optimization of the Eaton Detroit Locker / NoSPIN. Copying the form and appearance of a Detroit Locker / NoSPIN does not simulate the engineering, quality, or value of the product.