The National Highway Traffic Safety Administration has officially closed an investigation into 2003-'10 Dodge Vipers this week after almost eight months.

A probe was opened after the NHTSA received a number of consumer complaints of crashes related to rear suspension problems.

Approximately 9,670 vehicles were involved in the probe.

"Analysis of the failure data indicated these are random events and do not show any clear patterns related to vehicle build range, vehicle age or mileage," NHTSA said in a statement on the issue.

 NHTSA received at least 10 complaints about the Viper, and approximately eight crashes have occurred.

Owners claimed incidents were caused by rear knuckle failure while driving, according to the NHTSA in its summary.

After a review of "physical evidence" the automaker agreed that six out of the eight vehicles involved in an incident "were the causal factor of rear suspension control knuckled failure."

"Examination and testing of failed knuckles have not identified evidence of a manufacturing or design defect in the parts," said the NHTSA.

The investigation covered the 2003-'10 Dodge Viper SRT-10, Dodge Viper Competition Coupe and ACRX models.

The agency first launched an investigation back in April. 

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