WASHINGTON - Ultraviolet radiation is the major suspect believed responsible for the voluntary recall of more than 8 million cars with ABS seat belt buttons, according to the government's chief investigator. The buttons, made by Tokyo-based Takata Inc., were installed in 1986-1991 cars.
John Bailey, Takata spokesman in Auburn Hills, Mich., said Japanese Synthetic Rubber Co. of Tokyo compounded the plastic for the buttons, and he said CibaGeigy supplied some of the plastic additives designed to fight UV breakdown.
Ciba-Geigy Japan Ltd. ``is one supplier of antioxidants and light stabilizers used for a variety of polymers and synthetic rubber made by Japan Synthetic Rubber,'' said Fred Vigeant, aCiba-Geigy spokesman at the company's U.S. headquarters in Ardsley, N.Y.
``Like other companies, Ciba supplied some of these products to Japan Synthetic Rubber. They were never a sole supplier,'' he said.
Federal officials explained the recall at a news conference in Washington last week. Richard Boyd, chief of the Vehicle Control Branch of the Office of Defects Investigation of the National Highway Traffic Safety Admin-istration, said he ``could not determine if the problem is inherent in the plastic'' used to manufacture the release button.
Boyd also said cold weather temperatures may have been a factor in the button failures.
Boyd said he got basic information about the seat belt latch buttons by doing detective work in an automobile junkyard in northern Virginia. He examined 40-50 release buttons made by Takata and found ``a large per-centage'' that were cracked.
Boyd said the prying force of repeated use caused chips of the plastic to fall into the latching mechanism, in some cases causing it to jam.
Boyd's work was the basis of the Department of Transportation's decision to ask car manufacturers to repair or replace Takata seat belts at no charge to car owners.
One of the orange-colored belt buckle buttons of those tested by NHTSA refused to catch at all, Boyd said. Considering the random nature of the test, ``having one of 50 or so fail means a lot,'' Boyd said.
NHTSA has fielded more than 900 complaints of poor operation or button failure. Federal officials said 90 injuries, but no deaths, had been reported from accidents involving the belt devices.
Nine car companies - General Motors Corp., Chrysler Corp., America Honda Motor Co. Inc., Nissan North America Inc., Mitsubishi Motor Sales of America Inc., Mazda Motor Corp., American Suzuki Motor Corp., Isuzu Motors America Inc., and Subaru of America Inc. - will offer free repair or replacement of the device.
NHTSA reached no agreement with Ford Motor Co. Inc. regarding its participation in the service campaign.
NHTSA officials would not estimate the cost of the recall.
Boyd said that after 1990, polyoxymethylene was used in the buttons.
There have been several earlier recalls because of UV light inhibitor problems. In October 1992, General Motors said it would recall all of the Chevrolet Caprice, Buick Roadmaster and Oldsmobile Custom Cruiser station wagons in the 1991 and 1992 model years.
Other UV-related recalls have involved Ford Tracer bumpers and Chevrolet Corvette armrests.