A lot of people ask questions, regarding this topic. I always want to answer them thoroughly, but until now I haven’t had the time and patience to share my knowledge…

What is the Limited Slip Differential and how does it work?

Definition:

The Limited Slip Differential also called LSD

for short is a friction type of a differential. It’s called that way, because of the two abrasive discs that are positioned between the cogwheels and the differential tape. In ideal road conditions the moving speed of the two spacer wheels is the same. When turning, the wheel which is positioned on the inside part of the turn is rotating slower than the other one. The difference between the rotation speed of the inside wheel and the differential tape is the same as the difference between the speeds of the outer wheel and the tape. However, the first one has a “-“ sign and the other has a “+” one. That is the exact moment when friction between the two disks appears. When one of the wheels is starting to increase or decrease its speed, for example in a turn, the friction forces have to be eliminated first.

Here is the simplest explanation I could think for:

How does this work:
Imagine that the car is lifted off the ground, the engine is working and the gearbox is set on 1st gear. The two wheels are moving with the exact same speed together, for instance 20 RPM.
When talking about an open type of differential, applying a force of 10N on one of the wheels will slow it with 10 RPM. Afterwards, the second wheel will increase its rotation speed with 10 RPM. If you apply 20 N of force on one of the wheels, it will completely stop and the other one will start rotating with 20 more RPM. The Limited Slip Differential is a completely different case. Imagine that someone applies 10 N on one of the wheels. If you are holding the second wheel, you will feel that it’s trying to rotate and you are applying more and more force to hold it still. If you were applying 20 N before that moment, afterwards the required force will be 30 N. If you don’t manage to apply 30 N, the other wheel will start rotating with 30 N.
When talking about LSD 25%, these friction disks to the following:
Now imagine that the car is still lifted and the gearbox is still shifted on 1st. So, you apply 100 N on one of the wheels. This amount of force is absolutely enough to stop its rotation. However, the LSD is set to 25%, meaning that the second wheel is experiencing 25 N of force. The wheel you are holding with 100 N of force will star moving once again.

The real life physics is a lot more complicated. We have other factors to consider here- engine torque, tarmac friction and a couple of different types of friction. All of these are complicated factors which affect the vehicle’s road behavior a lot!

I am posting a picture just to give you a better idea of what I am talking about.

Pros and Cons:
Just a quick side note: Pros and Cons can vary a lot. They all depend on personal opinions and preferences. What I’ve written is my own personal opinion. Feel free to disagree with it.

Pros:
-For starters, the Limited Slip Differential can really help you when faced with bad weather conditions. Mud, snow and rain are the right conditions for a car outfitted with LSD.
- The fun factor- installing a Limited Slip Differential on a vehicle makes it a lot more pleasant to drive. It also greatly aids drifting. However, having a lot of horse power under the hood and trying to drive like a pro can be very dangerous. Don’t take foolish risks!
- The Limited Slip Differential will really boost your car’s acceleration in drag race starts. This only applies for tarmac, however.
- Last , but not least- LSD will greatly aid you when performing brainless stunts! Now you won’t have to worry anymore when trying to drift alongside the fuel dispensers in the gas station!
Cons:
- The Limited Slip Differential is the wrong choice for inexperienced drivers. LSD can limit your control over the vehicle and lead to an accident, especially if you are driving on a wet surface!
- Installing a Limited Slip Differential means that you have to throw away any custom size tires you’ve got. All 4 wheels have to be equipped matching size tires.
- You will need to change the oil type you are used to and replace it a lot more often than before.
- As I already wrote, Limited Slip Differentials utilize a pair of abrasive disks. These disks get worn out pretty quickly. After a certain mileage you will surely need a replacement pair!
Additional information:
- If you modify the Limited Slip Differential you are outfitting your car with, it’s possible to get a better torque distribution. This is achieved by adding a few extra disks or removing the factory placed ones and changing them with bigger ones.
- It’s generally not possible to modify a open type differential into a limited slip one. However, there are a few exceptions.
- It’s also not possible to change the gear ratio of a differential. Again, there are a few exceptions.

Conclusion:
If you are an avid race driving fan, like driving fast in extreme road conditions or even prefer off road driving, then you definitely need a Limited Slip Differential. However, if you are afraid of driving a rear drive vehicle, then forget about Limited Slip Differentials. Buy yourself a new cosy urban car and sell the fun machine you are afraid of driving. Give others the chance to enjoy the blessing called Limited Slip Differential.

I hope I explained the pros and cons of the Limited Slip Differential quite clearly. A short disclaimer- I am not a professional driver. All I’ve written so far is the result of personal experience and preferences.

P.S There is something else I can teach you. I have a lot of experience destroying Limited Slip Differentials by careless and reckless driving. Let’s hope you will restrain from this kind of activities. : )

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