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Customer Support / FAQ's

This page contains some commonly questions that are often asked by customers .

Call, Fax, or Mail Us

Customer Service Line:

1-888-382-2953

Tech Help:

1-319-896-5617

Call 8 am to 5 pm CST Monday through Friday, for help with parts installation or application. Please have all relevant vehicle information ready when you call.

Order by phone:

1-888-382-2953

Use the Drivetrain America order line to place an order, get technical assistance, or check on product availability. The Order Line is open Monday-Friday 8am-5pm CST.

Fax your order:

1-319-364-1529

Mail in your order:

You can also mail your order to us at:

2150 Sadler Dr. SW

Cedar Rapids, IA 52404

Q. Does Drivetrain America offer local pick up of orders?
A. a.  Currently, Drivetrain America does not offer local pickup of parts at our warehouse.

Q. How can I figure out the ratio of my particular rear end? 
A. a. Look for any tags or stamping numbers in your housing. 
b. Count how many teeth are on the ring gear, as well as the pinion gear, then divide the number of ring gear teeth by the number of pinion gear teeth. 
c. Obtain any numbers off of your ring gear and pinion gear. We may be able to cross-reference them. 

Q. What do I need to identify a Dana differential?
A. The best solution to help us determine what parts are required when using Dana would be to obtain the B.O.M. number. 

Q. What is a B.O.M. number?
A. B.O.M. is for "Bill of Materials" which represents the parts used to build specific rear ends. Made by Dana.  Please see our TECH INFO PAGE. Check your parts and application on the net at http://www2.dana.com/expert/.

Q. What is posi and/or limited slip?
A. Posi and limited slip are the same. This occurs when both tires under a specific load are turning equally, yet when under an uneven load - one is allowed to turn at a different speed, which allows better traction, as well as comfort. They are two different words to describe an item; example: motor or engine. 

Q. How can I determine what ratio to use for my application?
A.

mph x gear ratio x trans ratio x 336 ÷ Tire Diameter = RPM 
Tire Diameter

Example: 
70 mph x 3.73 (gear ratio) x .67 (trans ratio) x 336 ÷ 27(tire diameter)   = 2176 RPM 

70 mph with a 3.73 ring and pinion over drive transmission in 4th gear with a 27" tire will perform at 2176 RPM

Q. How can I tell the difference between a GM 8.2 10 bolt, Buick/ Olds/Pontiac 8.2 10 bolt, and a GM 8.5 10 bolt?
A. Each of these has a different spline. 
GM 8.2 = 25 spline shaft 
Buick/Olds/Pontiac 8.2 = 27 spline shaft 
GM 8.5 = 30 spline shaft 

Q. What is the difference between a Performance Gear and a Street Gear?
A.

A street gear is designed for daily driving. Long distances and extreme heat are not a problem for these gear sets.  For this reason, these are also the gears of choice for oval track racing.

A performance gear is strictly for drag racing. In a situation where there is excessive torque, a street gear is not designed for this application, and a performance gear should be used. Pro gears are much softer than street gears, in which the teeth actually bend instead of snapping off, allowing a run to be completed.

Q. What is the proper way to measure a driveshaft?
A. Take your slip yoke for the transmission or transfer case and push it all the way in, then pull it out 3/4 to 1". This allows for normal riding position. Measure the driveshaft from the center of the u-joint cap to center of the u-joint cap at ride height. 

Q. Does Drivetrain America offer installation?
A. Yes, we install parts. We have a full service department with several qualified technicians. You may also ship your differentials, driveshafts, and transfer cases to us to have labor performed. 

Q. What is the proper backlash for my ring & pinion?
A. For light duty vehicles, (1 ton or less for street use), backlash is .007 to .010 (7 to 10 1000ths of an inch). For pro gears, backlash is .006 to .008 (6 to 8 1000ths of an inch). 

EATON PERFORMANCE DIFFERENTIALS

Detroit Locker

What kind of oil should I use? Can I use synthetic? Do I need friction additive/modifier?
A quality petroleum/mineral based oil works best in the Detroit Locker units. We do not recommend synthetic oil. Friction additive/modifier is not required.

Can I use the stock bearings?

In most cases the Detroit Lockers work with the factory (stock) bearings. The exceptions are: 10 bolt 8.5\8.6 GM axles, the “Performance” Dana 35 & 44 and GM 12 bolt with 35 spline axles. No other “special” setup is required.

What kind of break-in is required?

The Detroit Lockers do not require any break in.

When does a Detroit Locker lock?
The Detroit Locker is locked up 100% in a straight line or if you are spinning. The unit unlocks in a turn for the wheel that is turning the fastest.

When I step on and off the gas pedal, I hear the unit make a “clunking” noise. Why?
Because 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 going from drive mode to coast mode. Also with the vehicle on the ground and the transmission in neutral you will have 1\4 to 1\3rd of a turn of lash in the driveshaft, this is completely normal.

Can I run a Detroit Locker on the street?

Many people do use the Detroit Locker during everyday street use. The Detroit Locker is a very aggressive differential, so you will hear it and feel it everyday on the street. Eaton makes many applications for trucks that spend most of their lives on the road. (In the late 60’s, some Ford cars had the Detroit Locker as a factory option.)

How much horsepower and torque will the Detroit Locker take?
There are many factors to consider when determining if a specific differential will last in your vehicle. Horsepower and torque are important factors. However, the weight of the car, tire height/width, the terrain and suspension are all important things to take into consideration. For example, a setup that uses street tires will live longer because both tires will break loose and spin before any real strain is put on the unit. But as the tire gets wider, the stress on the unit increases because the traction is greater. When in doubt, the best bet is to call us with your specific application and driving conditions. But also keep in mind that the Detroit Locker is the strongest unit sold today and has been for many years.

Can the Detroit Locker be used in the front axles?
Yes they can, but you must have lock out hubs and they MUST be unlocked for on- road driving because of steering issues.

Can the Detroit Locker be repaired?
Yes they can. Should you need to repair a Detroit Locker parts can be purchased from any of our dealers. Call Eaton Customer Service so we can provide a blow up of the unit that shows all the part numbers and help you find out exactly what part numbers you need to purchase. At that time we can even recommend a company to buy the parts from.

What is the warranty?
The Detroit Locker unit is covered for one year from date of purchase against defects in materials and workmanship. The unit is not covered if the failure of another part (axle shaft or ring & pinion) damages the unit.

Eaton ELocker

How do I activate my ELocker?
ELockers are activated by a dash or council mounted switch.

What is the Warranty on the ELocker?
ELockers are guaranteed for one year against manufacturers defects.

What OE vehicles are equipped with the ELocker?

The GM H2 and H3 Hummers have factory Eaton ELocker options.

Are ELockers rebuildable?
Yes. Depending upon your needs, several types of service kits are available - the gear service kit, locking mechanism kit, stator/armature kit, and the universal wiring kit.

What locking modes does an ELocker have?
The ELocker operates as a standard (or open) differential. When the Elocker is engaged, the ball ramps or pins are energized, causing full lock.

Can I just purchase the wiring harness?

Yes, the wiring harness is universal to fit any vehicle, and can be purchased separately.

Is a relay necessary for ELocker operation?

That switch cannot handle the current that the ELocker needs. Therefore the relay is needed to run both the ELocker and the switch.

Can the ELocker be engaged “on the fly”?

Yes. You can engage it on the fly up to a certain point, probably around 15 - 20 mph. However, you must be careful that the wheel speed difference (between the right and left wheel) remains low, under a 50 rpm difference. Therefore we specify that the vehicle speed should be below 3 or 5 mph when engaging the ELocker.

Does ELocker have any special installation requirements?
Yes. All Dana 30 and 35 model Elocker differentials require LM102949 bearings and LM102911 races. See installation instructions.

Eaton Posi

What kind of oil should I use? Can I use synthetics? Do I need a friction additive/modifier?
Eaton Posi units perform best when using GL4 (or better) mineral/petroleum based gear oil. A four ounce bottle of friction additive/modifier is also necessary for optimum performance.

Is the Eaton Posi Rebuildable?
Yes. There are three main types of service kits available - internal spider and axle gear kits, clutch kits, and preload spring & plate kits.

Can I upgrade my Eaton Posi?
Yes. Both the clutch disks and the preload springs can be upgraded for extreme off road and drag racing applications. Posi units come equipped with 400lb of preload. They can be upgraded to 800lb, or even downgraded to 300 or 200lbs options.
Clutches - There are several types of clutch service kits. They range from the OE, 18 disc (standard), the 24 disc (high performance), and the modern day, high tech 14 disc carbon fiber design.

What is the warranty for the Eaton Posi?

The Eaton Posi is guaranteed for one year against manufacturers defects.

Truetrac

What kind of oil should I use? Can I use synthetic? Do I need friction additive/modifier?
A quality petroleum/mineral based oil works best in the Truetrac units. We do not recommend synthetic oil. Friction additive/modifier is not required.

Can I use the stock bearings?
In most cases the Truetrac units work with the factory (stock) bearings. The exceptions are: 10 bolt 8.5\8.6 GM axles, the “Performance” Dana 35 & 44 and GM12 bolt with 35 spline axles. No other “special” setup is required.

What kind of break-in is required?

The Truetrac units do not require a break in. The unit’s internals will take a little time (depending on driving conditions) to “seat.” Afterwards there will be a slight improvement in its performance.

When does the Truetrac lock up?

The Truetrac is a helical gear limited slip differential and never “locks up”. The Truetrac operates by transferring power from the spinning wheel to the wheel with the most traction. If one tire breaks traction, the amount of rotation (or spin) is controlled. The torque is then sent to the other tire that still has traction.

I use my car on the street and on the strip, will the Truetrac hold up?

On the street, the operation of the Truetrac will be transparent. You will not know it is there until you need it. In racing situations the unit will apply torque to both tires and launch straight as an arrow, time after time.

How much horsepower and torque will the Truetrac take?
There are many factors to consider when determining if a specific differential will last in your vehicle. Horsepower and torque are important factors. However, the weight of the car, tire height/width, the terrain and suspension are all important things to take into consideration.

For example, a setup that uses street tires will live longer because both tires will break loose and spin before any real strain is put on the unit. But as the tire gets wider, the stress on the unit increases because the traction is greater. When in doubt, the best bet is to call us with your specific application and driving conditions.

Can Truetrac be used in the front axles of full time 4 wheel drive jeeps and trucks?
Yes, it can. You will find will find Truetrac differentials to be very smooth yet effective in either end of your vehicle.

Can I repair the Truetrac if I need to?
The worm gears inside a Truetrac are maintenance free, and do not require regular service. Internal failure usually results in the damage of the worm gear pockets. Therefore, they are not rebuildable.

What is the warranty?
The Truetrac unit is covered for one year from date of purchase against defects in materials and workmanship up to a 38.”