You may have heard the term, “limited slip differential” before used by car dealers, mechanics, or off roaders but what exactly is it and why is it important to have on your vehicle? Limited slip differential was created in the 1930’s as a way to let the shafts at the diff turn at different speeds while limiting that difference in speed at the same time. So, why exactly is this helpful, you may ask? Well, by allowing a varied torque across a driven axle, it permits maximum traction to be accomplished by your vehicle. Though this is especially helpful for off-road applications or racing, it is nice to have on every vehicle.
How Does a Limited Slip Differential Work?
An open differential is used to make sure equal amounts of torque are applied to each wheel. It does so by using the engine to apply the necessary power to the gears for transference. It also uses your tires to apply traction to grip the road without slipping, which can happen in wet conditions or trying to accelerate too fast in dry conditions. Where does that leave you in the case that you find yourself with one tire in a compromising condition? Some of us have experienced this when we get a tire stuck in the mud. You end up free spinning a tire because the one that has some grip has been reduced to the same amount of torque causing you to remain stuck because the tire you need to pull you out will not spin at all.
Limited slip differentials use a synchromesh arrangement. This arrangement uses centrifugal force to limit how much torque is transferred to each wheel and allows that motionless wheel to continue to rotate. In other words, when your vehicle is experiencing slipping or going sharply around a curve, the limited slip differential lets the wheel that is not slipping have more torque and traction so that you do not end up spinning or stuck. Most limited slip differentials accomplish this through fluid filled housings and clutch plates. However, there are more efficient models that use electronically driven limited slip differentials that can vary speeds and torque much quicker.
How Do You Know When Your Limited Slip Differential Needs Replacement?
When your limited slip differential starts having issues, it can potentially create a dangerous situation. Or, you may find yourself stuck again. Here are some common symptoms of a failing differential:
- You may notice some traction issues such as not being able to accelerate as fast without your tires slipping
- You find yourself stuck on ice or in the mud
- Difficulty controlling your vehicle around corners or slipping and fishtailing in the rear end as you make fast turns
- Chatter, grinding, whining, or howling noises coming from the wheels. You may notice them get louder as you increase speed. Usually this will signify gears that are worn, need to be lubricated, or out of alignment.
- Clunking or banging noises as you make a turn. This can usually show that your spider gears are done. Over time the splines become rounded and do not perform as they should. Broken spider gears can also cause the differential to seize and create a horrible crunching sound.
- Clunking as you drive every few feet usually means a gear ring has snapped.
- Worn or chipped gears can cause a clinking noise that occurs regularly every rotation.
- Leakage near the seals
Types of Differentials
Before you run out and replace your differential, it is important to know what you have or what your options are so that you can choose something more appropriate for your vehicle and your application. These are the five typical types used in vehicles:
- Open Differentials: This type is the most common differential you will find on daily drivers today. It is inexpensive, reliable, and gives the regular driver great drivability. It is not meant for towing or high speeds because it lacks the power and traction needed for use under those conditions.
- Automatic Locking Differential: Many off-roaders favor this type of differential. It has outstanding traction and will lock and unlock itself without having to rely on any involvement from the driver.
- Limited Slip Differential: This type is also a favorite for off-road applications. It is also used by racers. Limited slip differentials allow for sharper cornering and terrific traction. It can get off-roaders out of a stuck situation or keep them from getting stuck in the first place.
- Manual Locking Differential: Some drivers prefer being able to control their differential to allowing it to choose when to lock and unlock. This type of differential gives them that control. Typically there is a switch or other means of control behind the wheel that a driver can apply to lock the differential when they feel they need an increase in traction.
- Spools: This type of differential offers the highest traction and strength. The spools are unable to slip so turning corners is a breeze. This type is very favored by off-road vehicle owners.
Having a limited slip differential on your vehicle can be a very handy thing. This is especially true if you are racing and need traction to keep you gripped to those tight corners. It is also helpful if you are using your vehicle in an off-road application where the likelihood of you getting stuck in some mud or on an edge increases. By allowing your differential to apply more torque to the stable wheel or allowing the outside tire spin faster around a curve, you can gain an edge in racing or stay out of an immobile situation.