What are u-joints, and how can you diagnose a bad one?

U-joints are a small, simple component - in fact, they have changed much since the very first automobiles. However, on any vehicle with a driveshaft, its ability to move depends entirely on the u-joint being there. You’ll often hear “maybe it’s the u-joints” as a solution offered for problems with a vehicle - but what are they, what do they do, and how do you know if yours is bad? Zarin Truck & Automotive in South Heights, PA has the answers.

What is it?

A u-joint, or universal joint, is a component that connects the driveshaft to the differential, and sometimes connects the driveshaft to the transmission or two driveshafts to each other. It’s a cross shaped piece with a bearing at each end, that allows for lateral and side to side movement of the driveshaft.

What does it do?

A u-joint allows for slight positions changed between the driveshaft, transmission, and differential. In other words; the driveshaft connects the transmission to the differential, but it can’t be a static, solid connection. Since the differential moves independently from the rest of the vehicle over terrain, the transmission and differential don’t stay perfectly aligned with one another at all times. The u-joint compensates for motion, keeping the driveshaft connected and spinning freely.

How do you know if it’s bad?

First of all, it’s important to remember bad u-joints only really apply to rear wheel drive cars, trucks, and SUVs. To a technician that knows what they’re looking for, a bad u-joint is obvious, since it displays specific symptoms. A bad u-joint can cause a clunking sound or jerkiness while driving, particularly when letting off of and pressing the accelerator. A bad u-joint can also cause vibration at certain speeds, emanating from the center or rear of the vehicle. If a u-joint is excessively worn, there’s an easy test you can perform. With your foot on the brake, shift the car into reverse. Then, shift into drive. If the vehicle makes a clunking sound, or you can feel it knock one time after engagement, a u-joint is likely the culprit. As it wears out, it doesn’t make a tight connection to the differential and driveshaft, allowing for too much play at the joint.

Fortunately, a u-joint is a straightforward and inexpensive fix, and one of our technicians can have you back on the road in no time. If you need a second opinion on whether or not your u-joint is going bad, our technicians will diagnose the issue prior to repair. Get it done sooner rather than later - if it breaks completely, the driveshaft will disconnect from the vehicle, which can damage your transmission, the underside of your car, and anything else around it - plus, the vehicle won’t be going anywhere until it’s fixed. We would hate for that to happen to our drivers, so that's why we want to provide competent repairs and service beforehand. 

No matter your repair or maintenance needs, we’ve got you covered. Our team's goal is to get you back on the road safely and quickly. For the best repair and service shop in South Heights, PA, call or stop by Zarin Truck & Automotive today.

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Thank you for visiting Zarin Truck & Automotive in South Heights, PA. Count on our automotive repair technicians to keep your car, truck, suv, or van on the roads longer and safer.

Schedule your appointment today (724) 375-7500.