Nasr has struggled to match team mate Marcus Ericsson this year, trailing three-nil in their qualifying head to head - a trait the Brazilian put down to a possible chassis issue.
"I can confirm I get a new chassis here," Nasr told reporters in Sochi. "Although F1 cars are made of many components and the chassis is just one part, I think it is a sensible step from the team that we are looking further to discover these handling problems and issues I am having in the car.
"Since we put the car on track in Australia we've been having this very strange behaviour - let's say it's very unpredictable to drive the car.
"There [was not a specific issue] they could identify, but as I said there are so many places to look at and for this we need resources and time. The cars haven't been back at the factory, we haven't had a full look into every detail.
"So it's a good step we're taking, ticking the box to see if there is anything wrong with the chassis. Let's see how the weekend goes. Last year I had one of my best races in F1, so at least I have this reference in my mind."
Nasr finished sixth for Sauber in Russia last year. The team's form over the first three races of 2016 has proved a stark contrast: the Swiss squad are yet to score points, with Nasr posting a best finish of 14th in Bahrain, and Ericsson 12th in the same race.
