5 Symptoms of a Bad Front or Rear Differential (and Repair Cost)

(Updated on September 29, 2020)

A differential is the part of a vehicle’s powertrain that allows two wheels to turn at different speeds. Differentials have one input and two outputs, with each output going to an axle or drive shaft which then connects to a wheel.

What is the Purpose of a Differential?

When you take a turn in your vehicle, the left and right wheels will take a slightly different path. The tires on the inside of the turn will make a circle with a smaller radius, which means it requires less revolutions of the tire to complete the turn.

If vehicles were not equipped with front and rear differentials, the left and right tires would be forced to spin at the same speed despite these different paths. This would cause one or both tires to slip, causing loss of traction, excessive tire wear, and additional stress on other powertrain components. 

The difference in speed between the two tires is due in part to the vehicle’s track width (that is, the distance between the left and right wheels). The greater the track width and the tighter the turn you take, the more difference in speed there is between the inside and outside wheels.

How Many Differentials Does My Vehicle Have?

Vehicles have a different number and placement of differentials depending on the number of driven wheels it has. “Driven” wheels are the wheels which receive torque from the engine.

Front and rear wheel drive vehicles are two-wheel drive vehicles. They have a single differential.

Front Wheel Drive

Toyota Corolla

Front wheel drive vehicles often have a transaxle, which is a single integrated unit that serves the purpose of the transmission, the differential, and the axle. On front wheel drive vehicles, the term “transaxle” may be used interchangeably with “transmission” or “differential” depending on who you talk to.

Rear Wheel Drive

bmw windy road

Most rear wheel drive vehicles will have a standalone differential between the rear wheels that is linked to the transmission via a driveshaft. A rear differential is colloquially called a “rear end” or rear diff by some people.

All Wheel Drive

all wheel drive Subaru

All wheel drive vehicles have three differentials: a front, rear, and center differential. The center differential splits the torque between the front and rear differential inputs, which each then split the remaining torque from left to right.

Four Wheel Drive

off road

Four-wheel drive systems found on trucks and SUVs typically have a transfer case instead of a center differential.

Types of Differentials

limited slip differential pros and cons

Open Differential

An open differential is the simplest and most common differential. Equal torque is applied to both outputs. This means if one tire loses traction, the other tire will be limited in the amount of force it can apply to the ground to propel the vehicle forward.

Locking Differential

Locking differentials are typically found on purpose-built off-road vehicles such as trucks and Jeeps that come with off-road packages.

A locking differential spins the left and right wheels at the exact same speed, regardless of wheel slip. This differential is great for tough terrain when one tire could be in the mud, snow, or even the air.

You should take care not to lock the differential in a high-grip situation, such as on dry asphalt. This could put excess stress on the powertrain and damage expensive components.

Limited Slip Differential

A limited slip differential is a middle ground between an open differential and a locking differential. These are typically found on sports cars and higher end luxury cars. 

There are many different types and implementations of limited slip differentials. The basic idea is that when a tire slips, the maximum wheel speed of a slipping tire is limited. Torque is then transferred or multiplied to the opposite tire that still has grip. Ideally, this allows a vehicle to keep moving forward even if one tire has little or no grip.

Bad Front or Rear Differential Symptoms

There are a few noticeable signs that will present themselves if your front and/or rear differentials start to wear out or get damaged. Here are the most common symptoms that you can expect to happen if your differential goes bad.

1) Whining Noises

noise while driving

Whining noises are one of the most common and noticeable symptoms of a bad differential. This could be due to the components of the differentials not being lubricated properly.

Perhaps the differentials are leaking fluid and that is causing them to wear prematurely. Whenever their components are not being lubricated properly, you are likely to hear whining noises coming from the end of your car where the differential sits.

2) Tire Damage

worn tire treads

If your left and right tires are traveling at the same speed as you turn a corner, the inner tires are going to have more wear put on them because they’re being forced to rotate faster than they should be. This will cause your tires to wear prematurely.

If your differential is locked you may also experience tire scrubbing, which is the sound of your tires gripping and slipping in quick succession. Depending on the rubber compound, this may sound like a rapid squeal or a chirp. There will likely be some vibration to the rhythm of the sound.

3) Difficult Handling

canyon hills

Differentials are what allow your vehicle to corner comfortably when you make a turn. A failing differential is likely to upset the cornering ability of your vehicle and make it feel unstable.

Anytime you notice handling difficulties when turning or going around a corner, get your vehicle to a mechanic as soon as you can to have it checked out.

4) Vibrations

no power steering

If the universal joints of your differentials get too worn out, the drive shaft will start to vibrate. You will feel the vibrations even more as you step on the gas pedal to accelerate your vehicle. The vibrations will get even worse if there is a differential fluid leak.

Although this might not seem serious, you should let this be an early warning sign that you need to have your differentials checked out.

5) Gear Grinding

If you have a worn differential, its gears may start to grind more. This may even cause humming noises to emerge from the grinding of the gears. You will hear the humming sound get louder as you accelerate the vehicle.

If you hear this, it’s a good idea to have your differential inspected, and possibly the transmission too. If you catch it early, the fix could be as simple as a gear oil change.

Front or Rear Differential Repair Cost

The average cost of repairing bad front differentials and rear differentials will depend on the severity of their condition. Generally speaking, it should not cost more than $400 to repair most rear or front differentials. Most people pay around $200 to $300 though.

This would involve repair work related to adjusting the backlash and replacing the oil seal of a differential. But if you need to completely rebuild a differential, then your repair costs will be between $400 and $800.

This is still cheaper than having to replace an entire differential, which would be between $1,000 and $2,000.

35 thoughts on “5 Symptoms of a Bad Front or Rear Differential (and Repair Cost)”

      • I have a ford ranger and when it backs up in reverse it makes a loud thumping noise from the back. Any suggestions on what might be wrong?

      • I’m not sure Jacob, as it could be a number of things. Try to determine if it’s coming from the differential or the suspension.

        One time I had an issue where my sway bar was binding on the bushings and would clunk when backing out of my driveway on a hill. A little silicone spray on the bushings fixed the issue.

  1. A friend of mine told me it cost him 8k to repair rear differential on a BMW. Is this common? I have an srt8 and worried as I have turning noise and he believes it is the diff….ugh! Advice?

    Reply
    • That’s very expensive, but know that differential replacements costs will differ depending on the vehicle. Know what the problem is for sure before you replace the diff.

      Is it a clunk or a whine? If it’s a clunk, see if it could merely be a suspension component that needs replacing, as this will probably be far cheaper.

      Reply
  2. Hi, I have a 2002 Mitsubishi Shogun. I’ve got a flashing light on the dash next to the C/D LOCK. When I try to turn in a tight spot it feels like the brakes are being applied. Can you advise? Thanks.

    Reply
  3. I have a 1997 blazer the front passenger side is making a clicking humming noise when I’m in 2wd but it goes away in 4wd any help would be greatly appreciated

    Reply
  4. Hello, I have a 2015 BMW 535i, 78,000 miles. I took it in after hitting a pot hole on the interstate, the tire was beyond repair, had it replaced along with three others because they were worn. After the work was completed and I picked up the care, I noticed It was making a whistling sound in reverse, which was not there before I took it in to get the tires. I took it back to the dealer and was told I need to replace my differential which will cost me over $4,500.00. Comments please…

    Reply
    • Could you have damaged the differential when you hit the pothole? That is very expensive. If the car is not under warranty I would get a second opinion from an independent shop.

      Reply
  5. Hi Sean,
    I’m not sure if my car standards are any familiar with your expertise as I’m sending this message from Australia owning a Holden Captiva 2012 CG ll 5 Diesel 4WD.
    At some stage my car literally stopped in the middle of the road making extremely terrible sounds; I managed to get it to a nearby mechanic where I was told I would need to change both transmission and transfer case which would cost a considerably great amount; when I looked into it carefully using my little mechanical knowledge and experience I realised that the transmission is fine and if anything the transfer case is causing all this dilemma; finally at my own risk the mechanic changed the transfer case and the car was back to normal BUT there was a little grinding noise coming from under my feet (as you know we are right hand side drivers in Australia) between ~40-60 kms/hour of speed ONLY when the car is cold in the morning and eventually would go away when it drives for let’s say 45 minutes (completely gone to a point that by the time I get to my other mechanic who’s quite far the sound would be gone and he wouldn’t be able to pick up on it for diagnosis).
    I additionally changed the transmission oil, transfer case oil and front-left wheel bearing hub. As I drove the car more and more I realised the noise is increasing more noticeably to a point that again it stopped moving, flashing the engine light and feeling like the front Axel Shaft has disengaged; this would happen if I accelerate harder; I revved it slowly again (enough to move the car back to the mechanic) and ordered new front right hand Axel Shaft as well as wheel bearing to make sure I have done al that I could possibly do to narrow it down to the issue. Now just yesterday I got the car back and it seems all good BUT there’s still a very little grinding sound coming from the same place but surely not in the same magnitude as before. I would like to ask:
    1- if this could be from the front differential lacking proper or even any oil (as it is the main part connected to the Axel Shafts) or anywhere else you believe the grinding sound is getting produced from?
    2- in my case would the front differential oil be same as the transmission oil? (I mean are they two separate oils that need changing/service)
    Please forgive me for my mind-toiling words and I deeply appreciate your help in this regard.

    Note: the same little grinding sound comes out during the same speed range ~40-60 when the car is cold and for some reason when I go over road bumps/humps the noise increases instantly and goes back to normal like sound-waves (but this all happens in a small noise-scale; not loud).

    Thanks again

    Reply
    • Hi Saleh, I’m really not sure. Could you describe the grinding sounds in more detail? What codes were stored?

      1. You might be onto something with the axle shaft/front differential theory, but I wouldn’t expect this to flash a check engine light. Wouldn’t hurt to check on the oil though.
      2. I’m not sure if they use the same oil. You will probably have to do a bit of reading online to confirm that.

      Reply
  6. It is similar to the exhaust sound but in the form of grinding which can be felt from the front end.
    Yes; I actually checked with a mechanic and was told that the transfer case as well as front differential use the same oil.
    Out of precaution I again changed the transmission and engine oil; still can hear the noise 🙂
    The catch to it is that once the car warms up after let’s say 45 mins the noise goes away unless when driving on lower gears going up a steep road.
    I’m quite perplexed by this issue!

    Note: someone told me it could be from the engine mounts but I can’t put the bits of the puzzle together as to why then the noise goes away when the car warms up and how it is related to the mounts?!

    Reply
    • I wouldn’t think it would be the engine mounts, but I don’t know. Your previous description sounded like a drivetrain issue. Bad mounts wouldn’t cause your car to stall in the middle of the road like that.

      You’re best off going with what the mechanic says since he can see the vehicle in person.

      Reply
  7. Hi everyone !!
    I have 2010 Ford Explorer 4.6 4WD. In the front differencial where the driver side axle goes inside, the oil flows. I picked SUV up on the stands and turned it in drive. Axles are spinning but where the leakis, the part of axle that goes in has play because you can see when the axle is spinning it makes wider rotation. The inner seal is bad, can be bearing bad too? I hope everything is ok inside. The second thing is,is it normal when I turn on the 4×4 auto, is the front drive shaft spinning ? I know it’s ok on 4×4 Hi or Low, please help.
    Thank you

    Reply
  8. My 2001 Chevrolet Impala 3.4 has a slipping when coming out of park to go into the drive ( move mode) it acts like a jolt before it gets going. About 3 jolts before catching. Can someone please let me know what you think it may be?
    Could it be the front differential??? It’s front wheel drive.

    Reply
  9. I have a 2010 Ford Explorer that is “shuddering” when turning (especially during deceleration for turns). It makes a clunking noise and you can feel a significant vibration in the pedals. It seems worse with left turns.

    Reply
    • Could be a wheel bearing, CV axle, tie rod end, or even something else. It’d be best to have it inspected soon. I wouldn’t drive around much until you can get that fixed.

      Reply
  10. I have a 2011 Subaru Forester, 95807 mileage. Broken front diff. Dealership says 11K for repair. Transmission and labor. Otherwise in great shape. Should I try a second opinion?

    Reply
  11. Hello

    Car makes humming noise when driving on the frw at higher speeds seems like it get bigger the faster you go. Is it wheel bearing ?also howles on low speed
    Is it differential ?

    Reply
  12. Hello, I was wondering if you could give me advice on my 2010 6.2L awd Escalade Luxury trim. Right after replacing my front Z95 shock absorbers (struts) with O.E.M ones, I get a clunking noise from the left side when going over wash board roads (that I wasn’t getting before replacement). It can be the smallest imperfection in the road n it will make a clunk/clunking noise, yet it will not make that noise if I drive through a gravel parking lot. I’ve since replaced both upper and lower ball joints on the driver and passenger side, plus new hardware as well ( all O.E.M.). Front sway bar bushings and end links are good, I just replaced the rear sway bar bushings (that made a big difference in handling). the outer cv boot on the driver side has a tear in it, but I get no noise when going in circles in either direction. I’m getting ready to put in a new cv shaft on the driver side (I didn’t trust the boot repair kits I’ve seen for sale). I’m wondering if the torn cv boot could be causing the clunking noise that is driving me crazy. If not, I really hope that it is not the front Differential. thank you in advance. My vehicle currently has 118,000 miles on it. I’m also getting no other noises besides that clunking noise almost like metal on metal.

    Reply
  13. I have a 1995 F350 with duallyies. I replaced back four tires at the same time but outside are worn much worse than the inside. A friend said it might be the differential. Any thoughts?

    Reply
  14. I have a 2015 Chevy Traverse with 97,000 miles on it. Noticed a growling noise in the front driver’s side starting about 6 months ago. I can hear it most all the time, but especially when I decelerate as I would when about to make a turn. Had mechanic drive it and he said it was wheel bearing. However when they changed the wheel bearing and drove it the sound was still there. He told me it could only be one of two things — wheel bearing or differential and it was not the wheel bearing. He told me to drive it, no problem. What’s your opinion?

    Reply
    • I don’t know, I haven’t heard the sound or driven the car. I would go with the mechanic’s recommendation, but you can always get a local second opinion if you are unsure.

      Reply
  15. 2013 Toyota Camry driver side tire area feels like it “drops” slightly when I turn left and it feels like it’s vibrate/stuttery when in drive though very little what could this be?

    Reply
  16. Hello I have a Volvo XC60 and am hearing a slight clunking noise from the rear when I turn left from a stopped position and started noticing a slight vibration while driving on the interstate. Would I need the entire differential replaced or is there something else I can look for.

    Reply

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