NASCAR has lowered the boom on crew chief Chad Knaus -- again.
On Wednesday, NASCAR suspended Knaus, the crew chief for five-time Sprint Cup champion Jimmie Johnson, for six races and fined him $100,000 for unapproved modifications made to the C-post areas of Johnson's No. 48 Chevrolet.
The violations were discovered during inspection prior to the Daytona 500. C-posts are contoured sheet metal stretching from the roof to the rear edge of the window openings.
In addition, car chief Ron Malec was also suspended for six races and both were placed on probation through May 9.
Johnson also lost 25 driver points and his Hendrick Motorsports team lost 25 owner points.
Hendrick Motorsports plans to appeal and the suspensions will be on hold until the appeal is heard. However, the points are docked now, leaving Johnson -- who earned two points with a 42nd place finish in the 500 -- with -23 points heading to this weekend's race in Phoenix.
"Our organization respects NASCAR and the way the sanctioning body governs our sport," said HMS owner Rick Hendrick. "In this case, though, the system broke down, and we will voice our concerns through the appeal process."
Knaus has had plenty of run-ins with NASCAR in the past.
He's been suspended four previous times, but had a two-race ban in 2005 overturned in the appeals process. His most recent suspension was for six weeks in 2007 when NASCAR said he had altered the front bumpers of Johnson's car at a road course race at Sonoma, Calif.
Johnson and Knaus have won 54 races and five championships together.