Chevrolet Designs for Pothole Perseverance
DETROIT--March 14, 2014: Spring hasn’t arrived, but the potholes have. While no one plans to hit them, they are inevitable and in many cases unavoidable. More than an uncomfortable nuisance, they can damage tires, wheels and suspension components.
Chevrolet helps combat the effects of potholes by taking them head-on, testing vehicles such as Malibu and Silverado on carefully engineered roads within the General Motors Milford Proving Ground that are laced with manufactured potholes ranging from mildly annoying to chassis-rattling. The intentionally poor road conditions help engineers thwart the bumps a vehicle takes and tune suspensions to minimize discomfort to passengers.
“We have a wide variety of road surfaces that simulate real-world road conditions around the globe,” said Frank Barhorst, who supervises the Product Usage Measurements and Applications group at the Proving Ground near Detroit. “The range of test road surfaces goes from good to bad, so that we can find the most balanced condition for each vehicle we develop – and believe me, we’ve created some of the worst potholes you’ve ever seen.”
Potholes are most prevalent in the spring because the moisture in the small holes and cracks in the road during the winter alternates between freezing and thawing as temperatures change, causing expansion and contraction of the road surface. Then, the pavement breaks up under the weight of normal vehicle traffic.
One of the major reasons vehicles sustain damage when they hit a pothole is because load is not transferred properly. The engineered potholes at Milford help experts re-create load conditions that occur when a vehicle hits one on a non-controlled surface. GM has collected that data for the past 40 years, using it to design and engineer new vehicles better able to absorb pothole abuse.
The extreme durability tests extend beyond pothole-cratered pavement and includes terrain such as construction sites and off-road-driving environments for Chevy’s trucks and SUVs.
“Every Chevrolet built globally goes through this type of testing. And we design our vehicles to absorb the load when they hit a pothole,” said Barhorst. “The data we collect on our test course helps us to integrate loads between interconnecting parts, and capture and fix potential problems as we design Chevrolets.”
While no technology will help drivers avoid every pothole, Chevrolet models share traits – such as robust body structures – that reduce vibrations generated by sudden, harsh impacts. The strong body structures also enable engineers to tune the suspensions more precisely, for smoother, more controlled driving experiences that help mitigate the effects of smaller and moderate potholes.
Chassis and suspension updates inspired by the all-new 2014 Impala also contribute to the a dynamic driving experience in the 2014 Malibu, including rebound springs in the struts on 2.5L-equipped models. More refined calibration of the dampers results in a smoother overall ride and improves body roll control and weight transfer during acceleration or turning. That helps keep the wheels planted, contributing to a more precise, controlled feel – especially while cornering.
Tire and wheel design and construction also play a vital role in managing potholes. GM engineers its tire technology specifications with an eye toward fuel economy, quietness, tread wear, braking distances and the ability to withstand potholes.
“On the wheel side, we’ve developed a premium process for flow-formed rims,” said Dave Cowger, GM Tire & Wheel Systems Engineering. “On the tire side, we’ve made improvements to the body side including the cords in the tires, which make the tires stronger and allow the vehicle to withstand impact better.”
The team that engineered the new Silverado went to extremes to ensure it would exceed the demands of truck customers. GM’s new full-size trucks underwent more than 6 million miles of durability testing at Milford, over the deserts and mountains of Nevada and across the frozen flats of Kapuskasing, Ontario. That’s equivalent to 240 trips around the earth. In addition, the trucks accumulated more than 7 million real-world miles during final testing, bringing total test miles to more than 13 million.
Chevrolet Certified Service offers these tips for avoiding and managing potholes:
Always inflate tires to the number on the tire inflation placard on the inside of the driver’s door opening Tire inflation should be checked cold, before driving Each 10-degree F change in ambient temperature changes the effective inflation pressure by 1 pound. This means during the course of a winter day going from 40 degrees F at noon to 0 degrees F at night, tire pressure can drop 4 pounds, enough to affect its ability to resist pothole damage Use winter-rated tires Watch for street hazards Remember that dirty headlamps and worn wipers hamper visibility If you hit a pothole, visibly check your wheel and tire for obvious damage and have your Chevrolet dealer check to see if the vehicle needs a re-alignment or if there is suspension damage.