DETROIT — General Motors has sued a supplier, saying it has spent more than $30 million fixing problems in the steering systems of the Chevrolet Cobalt, its best-selling small car, and other vehicles.

GM said customers have complained about unusual rattles, "clunks" and other noises. It pinpointed the flaw to "excessive gear backlash," which causes problems in the steering column when driving on rough roads.

The lawsuit names JTEKT North America, based in Plymouth, Mich., and an affiliated company, JTEKT Automotive Virginia of Daleville, Va.

GM said it wants to be paid for replacing thousands of parts under customer warranty claims on the Cobalt, G5, HHR and other cars, starting with 2005 model year.

By fall, the cost had exceeded $30 million, and "GM's damages are expected to continue to increase as additional warranty claims are made," the automaker's lawsuit said.

"JTEKT contends the components all met the specifications and testing requirements that GM gave it," said Bob Haddad, a lawyer for the supplier. "The issues do not affect the operator's ability to control the vehicle. This is a noise issue."

The steering systems are in tens of thousands of GM cars. It is not considered a safety issue, said Alan Adler, a GM spokesman.

He said the lawsuit likely will be settled out of court.

The Cobalt is GM's best-selling small car and its highest-mileage vehicle. The company sold 90,940 Cobalts through October, but sales are down 46 percent from the same period in 2008.

The car, built in Lordstown, Ohio, is due to be replaced next year by the Chevrolet Cruze.