Three NASCAR Sprint Cup car teams have had their crew and car chiefs suspended for the rest of the 2011 season, following the discovery of modifications made to the windscreens of the #00, #47 and #56 cars of David Reutimann, Bobby Labonte and Martin Truex Jr. respectively.

The unapproved modifications to the windscreens of the three cars - which made them thinner than allowed by NASCAR regulations - were discovered during pre-practice technical inspections at Talladega Superspeedway on Friday.

NASCAR issued the penalties on Tuesday in a statement that said all three cars were found to be in violation of Sections 12-1 (actions detrimental to stock car racing), 12-4-J (any determination by NASCAR officials that the race equipment used in the event does not conform to NASCAR rules detailed in Section 20 of the rule book, or has not been approved by NASCAR prior to the event) and 20-3.2.1A (unapproved modification to an approved windshield) of the 2011 NASCAR rule book.

As a result, the crew and car chiefs of all three operations were suspended for the remaining four races of the 2011 season. The crew chiefs have also been fined $50,000 each, and Bobby Kennedy, director of competition for Michael Waltrip Racing, has also been placed on NASCAR probation until the end of the year.

In addition, 25pts have been deducted from both the car owners and drivers' Sprint Cup championship standings. None of the drivers affected are involved in the post-season Chase championship shoot-out.

Michael Waltrip Racing - which fields the cars of Reutimann and Truex, and builds the Labonte car for JTG Daugherty Racing - said that it would not be appealing the penalty.

"Michael Waltrip Racing is ultra-sensitive and very serious about working within the guidelines of NASCAR policy," the team said in a statement. "We do not condone this type of activity and as such we will take appropriate internal corrective action immediately. We thank NASCAR for providing a fair and equitable platform for all of its competitors and respect its decisions."

"We are very disappointed in this entire situation and we will not appeal NASCAR's ruling," JTG Daugherty Racing co-owner Brad Daugherty concurred. "We look forward to racing at Martinsville Speedway this weekend and getting ready for next season."

The #15 car driven by team owner Michael Waltrip was not found to be in violation of the rules, and is unaffected by the penalties. There will now have to be an enforced personnel reshuffle across the teams to address the suspensions of the key staff.

For Reuitmann's #00 team, Bobby Kennedy, executive vice president of race operations, takes over as interim crew chief in place of Rodney Childers, while race mechanic Chris Hall stands in for suspended car chief Steve Channing.

For Truex Jr.'s #56 team, veteran crew chief Pat Tryson steps in for Chad Johnston as interim crew chief at Martinsville, and race mechanic Allen Mincey takes over as interim car chief in place of the suspended Tony Lunder.

At JTG Daugherty Racing, team chief race engineer Brian Burns will assume the role as crew chief for the Bobby Labonte's #47 replacing Frank Kerr, and Bob Bechstein has been named car chief replacing Raymond Fox.

All the suspended staff are expected to resume their normal positions once the penalties have been served.

The penalties are more severe than those handed down to Joe Gibbs Racing earlier in the season over modified oil pans. That's because in JGR's case the violation was not submitting the modified parts to NASCAR for explicit approval, but the oil pans did not themselves breach the rules. In this week's windscreens penalties, the modifications did breach regulations and were also made to parts that should not normally be modified by race teams during the season.