DEAR CUSTOMERS: IN AN EFFORT TO MAKE IT EASY FOR ALL TO ENTER THE BUSINESS COMPLEX, PLEASE DO NOT PARK IN THE ENTRANCE DRIVEWAY THAT IS ADJACENT TO ROSWELL RD.  CUSTOMERS OF OTHER BUSINESSES USE THE ENTRANCEWAY AND WILL HAVE DIFFICULTY ENTERING IF YOU PARK THERE.   PLEASE PULL DIRECTLY INTO OUR PARKING LOT AND WE WILL ASSIST YOU.  THANK YOU (404) 252-3014 Ext 232

8155 ROSWELL ROAD
SANDY SPRINGS, GA 30350

Mon-Fri: 7AM – 6PM
Saturday & Sunday: Closed

A Tribute to Roderick L. “Rod” McCullough
Founder of McCullough Auto Care & Tire

With heavy hearts, we announce that the McCullough Auto Care family has lost our father, founder, and mentor. Roderick “Rod” L. McCullough passed away peacefully on February 1, 2025, at the age of 86. A man of integrity, quiet strength, and entrepreneurial spirit, Rod built a lasting legacy in both business and community, leaving behind a life marked by dedication, service, and love for his family.

Roderick moved to the Atlanta area from his native home in Anderson, South Carolina, in the 1960s, focused on starting his family business. He became a successful businessman during the 1970s, owning and operating several Shell service stations throughout the area. In 1969, he founded McCullough Auto Care in Sandy Springs, Georgia, with just $1,200 and a clear vision. Over the decades, Rod grew the business into a trusted name, known for its honest service and family-oriented values.

Rod found joy in life’s simple pleasures. He loved long bike rides, peaceful walks along his favorite beach, and cheering on his beloved Clemson Tigers. Above all, he was most proud of his family. He celebrated their accomplishments with pride and never missed an opportunity to remind others that “family is the most important thing in life.”

Rod’s legacy lives on through his children and grandchildren, many of whom have followed in his footsteps and contributed to the family business.  Through every customer served, every child mentored, and every value passed down, Rod McCullough’s legacy endures — a testament to a life well-lived and a family business built on trust, hard work, and heart.

A damaged differential can negatively impact your safety on the road. This article outlines the function a differential has on your wheels and how you can detect the symptoms of a bad differential. 

What Does a Differential Do?

To understand the differential, we begin with the transmission. Your car’s transmission sends power to the driven wheels. If these wheels were forced to spin at the same speed, it would strain the axle and hinder your car’s turning abilities. This is where the differential comes into action, allowing each vehicle’s driven wheel to spin at a different speed while turning. 

Think of how a differential works by thinking of a high school track. You’ll notice that the starting lines for the outside lanes are ahead of the starting lines for the inside lanes. This compensates for the longer length of the outside lanes due to the track’s circumference.  Staggering the lines allows each runner to have the same distance to run overall.

The differential compensates for the difference in speeds between the inside and outside wheels during a turn. The wheels have to travel together, but they travel slightly different distances. The differential works to adjust wheel speed as needed to assist with turning.

Symptoms of a Bad Differential

A bad differential can compromise your vehicle’s turning ability and cause your wheels to lock up. Differential damage can spread to other components of your car. Look for these symptoms of differential damage to determine if you need repair.

  • Loose pinion-bearing preload – Listen for a high-pitched howling noise as you decelerate gears. 
  • Broken pinion-gear tooth – Listen for loud clicking or clunking sounds when driving.
  • Worn pinion bearings – Listen for whirring noises when driving at various speeds. 
  • Bad wheel bearings – Listen for rumbling sounds as you turn. Test this in an empty parking lot to be sure.
  • Worn carrier bearings – Listen for a whirring or rumbling sound when driving over 20mph. The noise may change pitch when turning.
  • Worn U-joints – Does your car shake excessively, especially while accelerating? Your U-joints may be worn out.
  • Broken cornering gears – Listen for banging, clunking, or clicking sounds while you turn a corner. Test this in an empty parking lot to be sure.
  • Worn transfer case – Listen for a clunking or clicking sound when you press or release the throttle.
  • Out-of-balance driveshaft – Feel for heavy vibrations while accelerating.
  • Insufficient lubrication – Your car’s differential needs sufficient lubrication to function correctly. Low gear or differential oil levels can cause a clunking or banging sound when cornering.

Schedule Differential Service with McCullough NAPA Auto Care

McCullough NAPA is a family-owned auto care center with 50+ years of experience. Our technicians are ASE Certified and equipped with the technology to diagnose your differential for damage and make repairs if needed. Allowing common differential problems to compound on each other can escalate into a major repair quickly. 

Schedule your appointment online for a differential inspection or service.