NASCAR had penalized Menard 25 points and the team 25 owner points. It suspended crew chief Slugger Labbe for six weeks, fined Labbe $100,000 and suspended car chief Craig Smokstad and engineer Grant Hutchens each six weeks.
RCR, which acknowledged the car failed the inspection at the NASCAR research and development center two days after the race, appealed only the suspensions to Smokstad and Hutchens.
The three-member panel of short-track operator Dale Pinilis and former car owners Robert Yates and Jack Housby all voted to uphold the suspensions.
RCR has the right to make a final appeal to NASCAR Chief Appellate Officer John Middlebrook, but an organization spokesman said Monday that no appeal is planned.