PRO TIP - A good guide is to have the tires rotated regularly, in any case, and they will be checked for unusual wear at that time. Most shops will recommend an alignment if they see signs of a problem.
The differential receives engine power from the driveshaft and splits the power input between two axle shafts, which drive the wheels on an axle. On a rear-wheel drive, there’s one differential on the rear, and on a four-wheel-drive vehicle, there is a front differential and a rear differential.
An all-wheel-drive vehicle is a little different. It has a front transaxle which drives the front wheels directly, and then, a driveshaft running back to a rear differential.
Costs of Differential Replacement
The average cost of replacing a differential is about $1700, with quite a bit of variation possible due to different designs, construction and availability.
The estimates of the rear differential repair cost on some common vehicles, using $100 an hour as a labor rate are as follows:
For a 2005 Chevrolet K1500 four-wheel-drive vehicle with a 5.3-liter engine, the labor time to replace the front differential assembly is 2.5 hours. It’s an independent suspension on the front, with a bolt-on differential housing assembly. A Zumbrota front differential assembly costs about $760, for a total cost of about $1,010.
To replace the rear differential assembly on this vehicle, the labor time is 2.5 hours. It’s a solid rear axle assembly with the differential gears integrated into the axle housing. A Cardone axle assembly costs about $1,322, which makes the total job cost around $1,572 on the average. There are a few axle capacity options and a few different gear ration options which can vary in parts cost.
For a 2005 Honda CR-V with a 2.4-liter engine, the labor time to replace the rear differential assembly is 2.5 hours. It’s an independent suspension, and the differential is a bolt-on housing assembly. A factory front differential replacement cost would be about $2,260, making the total job cost about $2,510.
For a 2006 Subaru Legacy with a 2.5-liter engine, the labor time to replace the rear differential assembly on the independent suspension is 2.3 hours. An OE differential with limited slip costs about $1902, and a differential without limited slip costs about $891. This makes the total cost for the job about $2,232 using the limited-slip option and about $1,121 without it.
For a 2010 Ford F-150 with a 5.4-liter engine, the labor time to replace the front differential is 3.4 hours. A Zumbrota differential assembly costs about $818, which makes the job cost about $1,158 in total. For this vehicle, the labor time to replace the rear differential is 4 hours. A Zumbrota axle assembly costs about $1944, which makes the job about $2,344 to finish.
For a 2008 Toyota Tacoma with a 4.0-liter engine, the labor time to replace the differential carrier on the front independent suspension is 2.9 hours. A factory front differential assembly costs about $2243, making the total job cost around $2,533. For the rear on this vehicle, the labor time to replace the differential is 3.3 hours. In this design, it’s a differential carrier that bolts into the differential housing. A factory differential carrier costs about $1,701, making the job cost about $2,031 to complete.
In all cases, about $15 to $40 might be added for new gear oil in the event that the new differential is delivered dry.
Causes of Differential Failure
There are a few things that can happen. Differentials are robustly built, but they do have to transfer all the engine power to the wheels. One of the more common failures is simple wear and tear, though in normal use, and with scheduled maintenance, a differential can last as long as the vehicle.
Moisture intrusion is rare, but water can get in past the axle seals or through the vent if the tube becomes detached. If water gets into the differential, it is mixed into a froth as the gears operate, which then, has poor lubricating properties.
Normally gear oil is checked for contamination when the oil is changed, and that is sufficient diligence. If a vehicle is used to put a boat into the water (which can involve submerging the rear axle), then, it should be checked more often.
If a vehicle is used for towing or hauling, that stresses the differential more and can also cause early wear. Sometimes, the way that goes is that the extra load and heat can cause wear on the ring and pinion surfaces, which puts metal into the gear oil. Metal in the gear oil is ideally collected by a magnet in the reservoir (or on the drain plug, or the differential rear cover), but gear oil is heavy and it’s necessary viscosity also makes it good at keeping debris in suspension. Metal or debris in suspension usually winds up in the bearings, so a little wear on the ring and pinion can easily lead to more general issues.
Rebuilding Instead of Replacement
It depends on the specific differential and the specific problem, but sometimes, rebuilding a differential is a better option than replacement. Where the differential housing and differential gears are an integrated unit, the assembly isn’t usually replaced unless the housing is bent or damaged.
In collision damage, that does happen. However, if the housing is fine and the problem is in the differential gears or bearings, the differential is usually rebuilt.
For example, on the 2005 Chevrolet K1500 rear axle in the example above, the rear axle housing with its integrated differential is available as an assembly. However, more often, if there is a problem in the bearing or gears, the unit is rebuilt in place.
The general cost of a rebuild option, if that is an option, is about 6 hours of labor time, and bearings are generally assessed and replaced as necessary. But a bearing and ring and pinion set can cost $500 to $600, or more.
As mentioned above, there are several axle options. That would cover most of the normal wearing parts, but there are still other possible problems and parts involved. If a differential is rebuildable, it usually does wind up being cheaper than replacing the whole axle housing assembly.
On a vehicle that uses a differential carrier, parts and procedures for internal rebuilds are often harder to come by. Rebuilding differentials is, in any case, a field of specialization that does take some specific training and experience, and usually some special tools.
Types of Differential Replacement
There are different differential replacement procedures that depend on how they are put together. Where a differential is on an axle using independent suspension, the differential is a bolt-on unit, the drive gears and housing are together in a carrier assembly. The CV axles and the driveshaft are disconnected and the differential unit unbolts from the subframe.
On a solid axle suspension, the differential gear assembly is sometimes housed in a carrier that bolts to a differential housing. The two-axle shafts are drawn out and the center gear carrier assembly unbolts from the housing and can be replaced as a unit.
In other solid axle suspensions, the gear assembly is integrated into the whole axle housing. In that case, the brakes are removed from the axles, the axle housing is unbolted from the suspension, and the whole assembly can be dropped out and replaced as a unit.
Servicing the fluid is the main thing, which is recommended every 30,000 to 50,000 miles on most vehicles. The next thing is taking it easy on acceleration.
Noise is the main symptom. All the moving parts in the differential have to operate smoothly, and if something is wearing out the first sign is usually noise on acceleration, or noise on deceleration.
Most shops can bolt in a new differential if that’s needed. If a differential is to be rebuilt, however, special tools and expertise may be required. Dealerships are usually capable, and sometimes 4WD specialty shops will be well equipped, but it’s best to ask about a shop’s experience with differential rebuilding in advance if that’s a likelihood.