Although you don’t see many driveshafts breaking down every day, like any other parts the driveshaft has a lifespan too. A rough estimate of a driveshaft lifespan is around 75,000 miles. So, if your vehicle has around 75,000 miles, what are the signs and symptoms that you must pay attention to if your driveshaft is about to break down? More importantly, is it safe to drive with a bad driveshaft?
”It is not safe to drive with a bad driveshaft because the driveshaft is responsible for transferring the torque and engine rotation into vehicle movement. If your driveshaft is failing or has already failed, you won’t be able to drive your vehicle any further. You could get stuck on the side of the road and all you can do is call a tow truck.”
Is It Safe To Drive With a Bad Driveshaft
The driveshaft will give you warning signs before it breaks down. It is possible to drive your vehicle with a bad driveshaft, but it is not wise to do so for a long period of time.
Once you notice excessive vibrations or a clunk noise every time you engage your transmission, it is a very common sign that your driveshaft is failing.
At this point, it is not safe to drive with a bad driveshaft. In the least dangerous scenario, you could lose power to the axle. You won’t be able to drive the vehicle any longer. But, you could be driving on a highway and the driveshaft could snap in half and parts of the driveshaft could detach and you would be dropping parts as you drive. That is not a safe scenario for you and the drivers behind you because one small bolt could rip a tire.
How Driveshaft Works
While driveshafts may appear to be fairly simple, they are in fact finely tuned and quite complex pieces of engineering. When a vehicle suspension compresses or rebounds, the driveshaft must follow the same movement as the final drive assembly.
The distance between the transmission output shaft and the final drive assembly will change proportionally to the arc that the final drive follows. The driveshaft is designed to compensate for this movement using a slip joint.
Vehicles with limited suspension travel use an extended yoke which is splined to the transmission output shaft. As the suspension moves and the driveshaft follows, the slip yoke will slide into and out of the extension housing. Vehicles with longer suspension travel are fitted with a slip joint positioned in the driveshaft itself. This joint performs the same function as a slip yoke.
It’s not uncommon for long-wheelbase rear-wheel-drive vehicles to be fitted with a center bearing which effectively turns one long shaft into two shorter ones. The center bearing is a sealed ball race mounted in a thick rubber casing which is then bolted to the chassis or underbody of the vehicle. Manufacturers do this to minimize driveline vibrations caused by the high rotational speeds of the driveshaft.
Most Common Symptoms of a Worn or Bad Driveshaft
A worn or bad driveshaft can be fully inspected and diagnosed by an experienced mechanic. But, are there any signs that a regular driver can notice and diagnose a bad driveshaft by himself? There are two most common symptoms of a worn or bad driveshaft:
1. Excessive Vibration
The first symptom of a drive shaft going bad is increased vibration. The driveshaft is located underneath the vehicle, underneath the floorboards, and usually in the center of the vehicle.
Due to the nature of the driveshaft location, the driver and the passengers are going to notice that there’s an issue with balance or that some of the joints are worn out on the driveshaft. Also, this is spinning at a different speed from the wheels and it creates a different harmonic on the vehicle.
2. Abnormal Noise
Probably one of the most interesting signs of worn-out driveshaft components is abnormal noise. These noises may be intermittent in nature, meaning you might not hear them all the time.
The abnormal noises could be heard by shifting from park to reverse to drive. You could hear a clunk underneath the vehicle while accelerating your vehicle from a complete stop.
Other abnormal noises that can happen are with the balance shafts and other issues with the shaft being damaged at the body itself. A technician may suggest just replacing the universal joint on the driveshaft. But, this is not a complete repair that solves the problem for the customer.
Just replacing this universal joint, does not address other issues with the driveshaft. Maybe there is a bushing that is worn out or a center support bearing that would need a replacement in the future. So, replacing the entire driveshaft may be the correct solution for that vehicle to return it to a like-new condition.