The function of the drive shaft is to transmit the engine torque from the gearbox to the wheels of the vehicle. Drive shaft is also known as a propeller shaft.
Majority of the vehicles are front-wheel drive so the torque would be transferred to the two front wheels known as a half-shaft. But other cars have what is called a drive shaft. It consists of the connecting shaft, the outboard fixed joint and inboard constant velocity joint. Then there are other elements like the torsion damper and the anti-lock system ring.
Usually the inboard CVJ comes in the form of a slip joint allowing the drive shaft to follow the wheel suspension movements. At the leading axle the outboard joint must transmit the torque effectively through a 52 angles degrees. The angles of the outboard joints at the rear axle are notably smaller.
Contained velocity drive shafts are subjected to a lot of stress all the time that the car is in operation. Next to the exceedingly significant displacement angles and translational movement, the bellows and joints should be able to withstand temperatures of between negative 40 and plus 120 degree Celsius and endure speeds of up to 2800 rpm. All parts should be maintenance free so it can transfer the needed torque in all engine speed and velocity ranges with dependable constancy preferably throughout the whole service life of the car.
Drive shafts are extremely balanced and weighted components since they rotate at extremely high speeds and torque values for the wheels to turn. Any issue with the drive shaft can mean drivability issues as well. Typically, a driveshaft issue comes with four signs that would warn the driver of an issue that must be addressed. These are:
- Vibrations – When driving a vehicle and you feel extreme vibrations that come from underneath it, your drive shaft may have an issue. This is typically the first symptom most people would notice when a drive shaft issue arises. These vibrations are likely caused by worn out bushings of the drive shaft. Such bushings keep the drive shaft from vibrating in normal circumstances.
If the issue is not repaired immediately, the vibration will get worse to a point that even your passengers will start feeling it too. And on top of that, other parts of the drivetrain can also be affected and damaged. But do note that vibrations that get worse with speed may mean your tires need to be balanced. Balancing your tires should be done on a regular basis. Read your owner’s manual to know the manufacturer’s recommendation.
- Strange Noises – Another sign of a drive shaft problem are strange noises. When the bearing or bushing supporting the drive shaft or the drive shaft U-joints wear out or fail, they disrupt the drive shaft’s ability to rotate properly. This may cause unusual rattling, scraping, clunking or even squeaking sounds from below the vehicle. A squeaking noise can also come from a U-joint that needs lubricated at low speeds. Clicking sounds specifically can indicate a faulty CV joint. Any sounds such as these are signs that the vehicle should be checked immediately.
- Turning Issues – Another plausible symptom of a failing drive shaft is having troubles with turning. A faulty drive shaft can keep the wheels from turning properly, which makes it hard for you to make turns. This problem limits your overall control of your vehicle. Any issues that can prevent you from driving your car properly should be addressed immediately for safe driving and continued vehicle use.
- Shuddering When Accelerating – Are you experiencing a noticeable shudder when accelerating from low speed or a stopped position? Chances are the component/s in your drive shaft is or are failing. A bad center bearing or a loose U-joint within the driveshaft can result in faltering acceleration. You can also hear noises while the car is shuddering due to the worn-out U-joint. When this happens you may want, go to a certified mechanic who can determine the issue and be able to address it.
Driveshafts are a significant component of the drivetrain and any problems with them can greatly impact the drivability of your car. As they are found underneath the car and connected to the transmission, they may be hard to access and service on your own. If your driveshaft is showing any sign of an issue, it is best to have the car checked by a professional mechanic to know whether the drive shaft should be replaced.
Causes of Damage
Damage to outboard and inboard joints of a drive shaft is typically caused by wear over time. It can also be caused by faulty sleeves due to using low-quality grease and in the majority of the cases due to not following the right procedures for installation and removal.
To maximize the running service of drive shafts they should be inspected on a regular basis by a professional mechanic. These inspections are done as part of the regular service checks recommended by car manufacturers. Another ideal time to check your drive shafts condition is when you are switching from winter to summer tires or vice versa.
During inspection the mechanic checks if the drive shaft is clean, seated firmly and if the sleeves are in good working order. Damaged sleeves should be replaced right away to avoid damage to the joint due to dirt penetration or grease escaping. When sleeves are worn or loose, there is a chance that the moisture or dirt have already gotten into the joint. If there’s no certainty if indeed it penetrated into the joint, both the entire joint and damaged sleeve must be replaced for safety reasons.
Majority of joint sleeves on newer cars are made from TPE. As a rule of thumb: A TPE sleeve should not be replaced by a rubber sleeve. Also, the appropriate specification must be followed when topping up with grease. Greases that are high performing can withstand temperatures of up to 160 degrees Celcius for short periods while standard joint lubricants can only withstand 110 degrees Celcius for short periods. Using the standard grease when high-performance greases are prescribed can lead to gas evolution from the grease and ultimately result in total failure of the joint.
Drive shafts and Safety
Drive shafts along with constant velocity joints are parts of modern cars which call for maximum safety. Most issues with the drive shaft come in the form of knocking noises when accelerating, when the suspension is being compressed and extended, and when driving around tight corners. To avoid putting yourself and the vehicle at risk, set a schedule with a professional mechanic if any of the above signs happen. Your drive shaft should be provided with the necessary service immediately.
Can you still drive when you’re experiencing drive shaft issues?
Yes, you can still drive with a faulty drive shaft but it is not recommended to do so for long. When part of the drive shaft snaps, you will lose power to that axle –best case scenario. The drive shaft can also fall and get wedged between your car and the ground, disabling you to make any forward movement.
On some all wheel drive vehicles, when one axle disconnects, the transfer case or center differentials, gets stressed and could lead to premature wear or even center differential failure.
Prior to Subaru began mainly using CVT transmissions, they had a viscous coupling center differential which is highly sensitive to prolonged speed differences between the rear and front axles.
When the driveshaft disconnects on one side while still rotating quickly, it will most likely cause massive damage to the underside of the vehicle. Keep in mind that if one end remains connected to the vehicle, the drive shaft will keep on spinning for a moment and remove anything in its path such as brake lines, handbrake cables, fuel lines, and even components of the wiring harness.
Repairing a Failing Drive Shaft
A mechanic can check the driveline and give information on the needed repairs required to have your vehicle to safe running conditions. It usually involves replacement of worn parts but it can also include replacement of the entire system. For older vehicles, replacement of the entire system is more common.
The price of the parts vary significantly depending on the type of the vehicle and the costs of labor also depend on how much work is required for your type of vehicle. Hence, the cost of repairing a driveline varies greatly, but repairs typically begin around $400.
For replacement of a half-shaft on the front wheel drive car, it will cost you anywhere from $470 to $940. Parts can cost anywhere from $320 to $750, for labor expect to spend around $150 to $190. For a rear wheel or four wheel drive vehicle, expect to pay higher, the repair costs can range from $600 to $2000.
Drive Shaft Maintenance Services
- Universal Joint Service – The universal joints on many vehicles are typically factory lubricated and sealed so it does not need lube for up to 100,000 miles. They are designed for long term trouble free use. The unique sealing method that the joint has keeps the grease from escaping and thus, lubrication is not required for a very long period of time. However, there are some universal joints that have lubrication fittings that require lubrication at regular intervals. Service to these kinds of joints (factory lubricated/sealed) is limited to replacement when there are already indications of excessive wear. The universal joints that come with lubrication fittings can only be lubricated using hand operated low-pressure grease guns.
- Slip Yoke Service – Another hard working part of the drive shaft that needs lubrication is the slip yoke. There are certain slip yokes that may be lubricated from the transmission and do not have a lubrication point from the outside.
It is recommended to have your universal joints greased every 6 months or every 6,000 miles to prevent issues and to lengthen its lifespan. Also, a good quality Extreme Pressure grease that meets the grade 2 specification of the National Lubricating Grease Institute.
How to prevent driveline failure
As a car owner, you can also do many things to preserve the driveline of your vehicle, from checking and ensuring your engine fluids are always at the proper levels to avoiding rough use of the driveline. It is always a good idea to ask a professional mechanic to check your car’s CV and universal joints whenever you bring your car in, just to check for excessive motion and lack of lubricant. We know too well that preventive maintenance can save you downtime with your machine, save labor, avoid injuries and further car damages that can be more costly.
Here are more specific tips you can do to keep your driveshaft in good working condition:
- Always have your universal joints well-lubricated. The lack of lubrication can lead to a train of damage that can be very expensive not only to the driveshaft but also to linking components such as pumps and gearboxes.
- Remove the covers and inspect the tubes of high use driveshafts on a regular basis. These parts can become worn out due to constant high torque movement. File off rough edges on the tubes so it won’t pick up on the other half of the tube.
- Make sure to replace the roll pin when you replace tubes since they can loosen because of torque loading.
- Apply a small amount of oil with grease on tubes as this will help to make slide easier and to make sure that the grease is distributed more consistently.
- Make sure drive shaft covers and chains are in protective and safe condition to prevent accidents and injuries.
Both professionally reconditioned and brand new replacement driveshafts for vehicles can be found on the market. When used driveshafts (majority of them will have been damaged) are reconditioned, the old parts are taken back from car garages for professional recycling in special production plants that follow the standards set for original equipment. All usable steel components are reused. The old driveshafts are checked, taken apart, cleaned, remachined and finally put back together to be available in the vehicle repairs market. Other materials obtained from the reconditioning process are disposed of properly in accordance to the applicable environmental guidelines.