Your car differential gears play an important role in keeping the vehicle running smoothly, especially when taking a turn or while running on a low traction surface in case of a limited slip differential.
Irrespective of the direction in which the vehicle is turned, the respective inner wheel speed is reduced and the outer wheel speed is increased to cater for the difference in the distance that the wheel needs to travel while negotiating a turn. That is why it is called a differential.
The issue with the differential gears and clutch packs arises mainly due to the poor maintenance of the vehicle or driving the vehicle on bad roads or abusive driving patterns.
Knowing the reason why the differential clutch pack goes bad would help you in taking care to avoid the damage to the differential clutch packs.
It is equally important to understand the differential clutch pack symptoms like vehicle rear end vibration, differential noise, bad vehicle performance, poor performance in low traction driving conditions, heavy gear oil consumption, difficulty steering, and improper tire wear pattern to avoid a major differential failure or vehicle accidental damage before it is too late.
It is easy to identify the signs of a damaged differential clutch pack if your vehicle is grappling with the issue related to a differential clutch pack.
If you are also experiencing the differential clutch pack symptoms, then you are in the right place!
Here you will get to know everything related to the problem and solutions to fix it. So, stay tuned!
Table Of Contents
What Are The Differential Clutch Pack Symptoms?
Putting too much stress on the vehicle parts by improper driving patterns may lead to differential clutch pack damage.
Too fast driving, frequent off-road driving, towing heavy loads like an RV or boat, overheating of differential by creating a smoke cloud by rash driving in open parking are the things that would lead to differential clutch pack damage.
Below are the few symptoms that you would experience when your vehicle’s differential clutch pack is going bad.
Rear end vibration
Rear end vibration is one of the often-reported symptoms in a rear-wheel drive which indicates that the differential clutch pack is going bad.
The rear end vibration gets severe especially when negotiating a turn because it is when any malfunctioning limited slip differential would perform worst.
The differential clutch pack chatter and create vibration because of the increased friction within the clutch pack.
If you have vehicle rear end vibration symptoms, then differential clutch pack damage can’t be ruled out.
Differential noise
When the differential clutch pack is worn out due to improper lubrication of clutch plates leading to wear and tear of the parts involved, it creates a typical shuddering or howling noise which results from the clutch plate friction and its associated vibration.
Poor vehicle performance
When the differential clutch pack gets damaged, one of the wheels would turn faster than the other and this leads to poor vehicle performance.
On moderate to heavy acceleration, the vehicle may try to move either to right or left depending on the location of the defective clutch pack.
This issue needs to be addressed soon before any mishap happens which may result in expensive repair operations.
Poor low traction performance
One of the main functions of the differential clutch pack in limited slip differential is that it helps in taking off the vehicle when one of the wheels is on a low traction surface compared to the other.
But when the differential clutch pack goes bad, the limited slip differential would lose its purpose to transfer power to the slower spinning wheel on the high friction road surface.
This would make the limited slip differential into an open differential with a loss of performance on low traction roads.
Heavy gear oil consumption
In the event of a bad differential clutch pack, it undergoes wear and tear and produces a lot of heat.
This evaporates the gear oil and whenever you notice that there is an increase in consumption of gear oil, you may attribute it to a failing differential clutch pack after a thorough inspection.
Difficulty steering
A failing differential clutch pack would put additional vibration load on the differential.
Any extra load on the differential would increase the difficulty in steering the vehicle.
Hence you may observe that the vehicle is relatively hard to steer. This becomes annoying especially when you drive off-road.
Improper tire wear pattern
A wheel tire over a period of running would worn-out owing to wear and tear.
But there is typical wear and tear pattern that one would observe due to normal running.
The vehicle vibration and noise associated with a bad differential pack would induce an improper tire wear pattern.
Since these vibrations are constant and it increases as we accelerate the vehicle, the tire would undergo an uneven and indescribable wear pattern in case of a bad differential clutch pack.
Tests To Confirm Bad Differential Clutch Pack
Put the vehicle gear in neutral mode, take the emergency brake off and jack up only one of the rear wheels and try to turn the jacked-up wheel with a torque wrench on the lugnut.
It shouldn’t turn easily, anything less than 35 ft-lbs of torque rotates the wheel, then it means you have screwed up the differential clutch pack and you need to replace the clutch pack.
A clutch pack in good condition would need a decent torque between 110 and 140 ft-lbs.
Alternately, if you lift the rear end in the air and hold one tire it should take some effort to turn the other wheel.
If it turns freely then it indicates that the clutch packs are burnt.
Solutions To Fix Bad Differential Clutch Pack
The differential clutch pack operates on the basic principle of stick-slip which is like building up and release of power while torque is transmitted between the clutch packs while negotiating a turn or driving on a low traction surface to maintain differential wheel speeds.
If your differential clutch pack is burnt due to frequent off-road driving or abusive driving pattern, etc., and looking for solutions to get rid of the symptoms, then below are the possible solutions to fix it.
Friction modifier
During vehicle running, the clutch packs undergo static (stick) and dynamic (slip) due to the stick-slip phenomena.
When the lubrication within the clutch pack is not sufficient and the clutch pack runs dry, the static friction overpowers the dynamic friction which leads to vibrations and the associated chattering noise.
The friction modifiers are typically used for ensuring smooth changeover between the static and dynamic friction and it increases the slip i.e. dynamic friction that results in quieter torque transfer while running.
If you are replacing the clutch pack, it is recommended to soak it in gear oil for a while before installing it inside the differential carrier assembly.
The quantity of friction modifiers is key to ensuring the quieter operation of the differential clutch pack.
It is advisable not to add too much friction modifier, otherwise, the dynamic friction (slip) will overpower the static friction between the clutch plates and your vehicle may not provide performance on low traction roads and surfaces.
Typically, you need to add 5 to 6 ounces of friction modifier to gear oil for ensuring a balance between static and dynamic friction and smoother differential operation.
Change driving pattern
Even after adding the right quantity of friction modifier to the gear oil, people still experience the chattering and shuddering noise resulting from the vibrations.
This would be due to the non-availability of friction modifier and oil to the interior of the differential clutch packs.
This vibration can be alleviated by running your vehicle in a figure of 8 patterns involving clockwise and anticlockwise vehicle movement for 5 minutes before resuming normal driving.
This typical driving pattern ensures that the clutch packs are open widely so that the friction modifier and the gear oil are pressurized and pushed into the internal surface of the clutch packs for complete lubrication between the friction and clutch plates.
This technique is followed by professional technicians to resolve the chattering or vibration problem in the differential.
Proper servicing
People often ignore the importance of maintenance of the vehicle with due inspection, refill, and replace process.
Nothing can beat the regular periodic maintenance when it comes to ensuring differential life.
Ensure that there are no metal particles inside the differential carrier housing after removing the differential cover.
The presence of metal particles would indicate there is a probability of some serious problem down the line due to the chipping of gears and pinion teeth.
It is recommended to check the color and smell of the gear oil during servicing to confirm whether it needs top-up or replacement.
Dark brown color and a burnt smell would indicate that it is time to replace the differential gear oil.
The typical replacement interval is in the range of 30000 to 50000 miles.
In case of a defective differential gasket, it may leak the differential oil and need to be topped up to prevent dry running of differential gears.
Apart from gear oil replacement, it is equally important to select the right grade of gear oil.
An incorrect differential gear oil may lead to poor vehicle driving performance.
Replace clutch pack
When you feel like there is a loss of available traction in some driving conditions or you hear a chattering noise from the differential which may be resulting from the worn-out clutch pack, then it is time to replace the differential clutch pack.
But replacing the differential clutch pack is quite a task since it involves a lot of complex dismantling and reassembling activities with the use of special purpose fixtures especially to assemble the spring-loaded carrier assembly.
Implement E-locker
The E-Locker is an electronic assist that is used to cater for traction on demand.
This would mean that the traction under certain driving conditions will not be automatic, you would select a switch to lock the differential to increase the traction on wheels while running on low traction roads.
A simple selection of a switch would make the differential behave like an open or limited slip type depending upon the requirement.
Replace differential
Replacing the differential is the last option that one can resort to when no other solution works or the differential is damaged to an extent that the problem becomes irreversible or the cause of the vehicle vibration and chattering noise remains unknown.
People often need to replace the differential clutch packs at certain intervals depending upon the driving conditions otherwise, the vibration or noise issue recurs.
One may resort to Eaton Detroit Truetrac differential which is a mechanical differential with no clutches involved, so there is no need for regular replacement of differential clutch packs.
Conclusion
There may be a certain class of issues in your vehicle whose fixes you can postpone but the issue related to the differential clutch pack if left ignored for a longer time, may lead to differential failure and improper vehicle driving performance especially when driving on low traction surface or heavy off-road driving, hence it needs immediate attention and fixes.
The symptoms that get manifested may be associated with other vehicle components.
Hence it is essential to thoroughly investigate and analyze the root cause before attributing the issue to a particular vehicle component.
The problem arises when the lubricant oil between the clutch plates tries to escape out.
Without the lubrication, the clutch plates will chatter and cause a vibration when forced to slide against the friction plates inside.
The clutch packs rapidly stick and release (slip) creating this vibration.
A differential clutch pack is a part that would sustain loads coming onto it without any issue, provided the differential, gear oil is inspected and replaced during scheduled periodic maintenance by adding the desired volume of friction modifier.
Replacing the differential may not be required in many cases but it depends on the condition of the differential clutch pack.
I hope with this information you will be able to understand the symptoms of a bad clutch pack and take a decision on whether the differential clutch pack needs replacement or not!
Happy Motoring!
References
https://www.fordforum.com/forum/ford-f-150-14/rear-differential-clutch-pack-problem-29763/
https://www.stangnet.com/mustang-forums/threads/what-happens-if-clutch-packs-go-bad.470516/
https://www.ford-trucks.com/forums/1231281-rear-end-chunk-thunk-noise-rear-diff-clutch-pack.html
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