What is a LSD Limited Slip Differential

Educational

Oct 09th, 2019

What is a LSD Limited Slip Differential

You might have probably noted when one of the drive wheels of your vehicle gets stuck in mud or snow, the tire with less traction behaves differently in different cars. Some cars will only turn the wheel that has less traction, while others will rotate both the tyres together. There are different types of differentials, and that accounts for this contrasting behaviour.


So what’s a differential?
 
A differential is a part of the front or rear axle assembly and is made up of a system of gears. It transfers the power from the driveshaft to the wheels perpendicularly. The transfer gears also allow the vehicle to make a smooth turn without one of the wheels skidding by varying the rotational speed of the two wheels. It enables the outer wheel covering the longer distance to rotate faster in comparison to the inner wheel when making the turn.



However, not all differentials work the same way. The different types of differentials are: open differential (OD), locking differential (locker), limited slip differential (LSD), and spool differential. For this article, let's look at LSD 


What's a limited slip differential, and how does it work?

LSD is a differential with a series of clutches (clutch pack) and is an upgrade of the open differential type. It makes it possible for the drive wheels to rotate at different speeds but limits the maximum difference between the two wheels.

It transfers slightly varying torque when the car takes a corner allowing smooth turning and equal torque when driving straight. When one of the drive wheels has less traction, the LSD behaves differently from the standard or open differential. For an open differential, you will find the wheel with less traction rotating and the other wheel stationary, which is not the case for the LSD. For the LSD, it has a set limit of the maximum speed difference between the two drive wheels. Thus it does not allow the drive wheel with less traction to spin significantly faster than the other. This property makes the car drive forward more efficiently than the open differential type when one of the drive wheels has less traction. 

How do I know the differential type of my vehicle?

It is simple to check if your vehicle has LSD. Jack up your car such that both your drive wheels suspend in the air. Rotate one of the wheels and note the reaction of the other wheel. If the wheels turn in the same direction, then you have a limited slip differential. If they turn in opposite directions, then your vehicle drives on an open differential.

Common Problems with LSDs

Differentials are one of the longest-lasting car parts, and you will probably drive your car for a long time without any significant issue. However, you may face a few problems that include the following:

  1. Low-level differential gear oil or excessively dirty differential gear oil - this causes the differential gear to howl or whine due to friction.
  2. Leaking differential gear oil - easily visible and gives a burning smell when it comes into contact with hot parts when a vehicle drives for long.
  3. Loose pinion-bearing preload - causes the vehicle to make some howling noises when decelerating.
  4. Broken or worn-out pinion-gear teeth - may cause slipping of the differential gear, creating some form of jerking.
  5. Worn-out transfer case - may cause some clicking or clunking sound when pressing the accelerator.
  6. Worn-out U-joints - causes excessive vibrations or shakes when a vehicle accelerates.
  7. Worn out carrier bearings
  8. Imbalanced driveshaft

Maintenance of the differential does not entail much. The differential only requires:

  • Servicing of the gear oil at the right interval
  • Refilling the differential gear oil when the level drops in between servicing intervals
  • Taking the vehicle to a licensed differential expert when you notice any issue or leaks on the differential
  • Replacing worn-out gears and bearings

Can I change the differential in my car?
 
Yes, you can swap your open differential for an LSD. There are various brands selling brand new limited slip differentials for all kinds of automobiles.