Michael Dunlop pulled the curtain down on the Irish road racing season with a flawless treble at Killalane in Co Dublin on Sunday.
Dunlop won the Open and Grand Final races on his MD Racing Honda Fireblade and also clinched victory in the Senior Classic race in a rare appearance.
Jamie Hamilton had a lucky escape in a 150mph crash in the Open event, causing the race to be red-flagged.
The Ballyclare rider suffered superficial injuries and was able to take his place on the grid for the Supersport 600 race, finishing fifth to secure the championship title.
William Dunlop won the race on Chris Dowd’s Yamaha R6, narrowly holding off a late charge from brother Michael to take the chequered flag by 0.081 seconds.
The Open race was declared a result after it was stopped twice due to crashes, with Hamilton going down on lap three in the initial race before Alan Connor slid off unhurt.
Dunlop was confirmed as the winner by 6.2s from Sheils, with Sweeney earning the final podium spot.
William Dunlop came through to clinch fourth on his 600cc Yamaha.
Sheils was crowned Irish champion from Michael Dunlop, who missed three rounds of the championship.
Dunlop, though, won each of the five races he contested at Cookstown, Tandragee, Skerries, Armoy and Killalane.
He underlined his class with a dominant win in the Grand Final, crossing the line with 11 seconds in hand over Sheils as Sweeney again took a lonely third place.
Seven-time Isle of Man TT winner Dunlop was denied a four-timer in the Supersport race, with older brother William hanging on at the end to complete another Irish national triumph.
The CD Racing Yamaha rider seized the lead of the race and opened a gap of over four seconds as Michael tried to find a way past Derek McGee.
Once Dunlop moved into second place he reeled in the race leader, but William claimed a narrow win with McGee finishing third.
Jamie Hamilton bravely battled to fifth place to clinch the title from McGee, adding more silverware to his trophy cabinet after the 22-year-old also won the Supertwin crown.
Hamilton skipped yesterday’s 650cc race, which was won comfortably by Sweeney, with McGee finishing as the runner-up, ten seconds adrift. Third place went to Andy Farrell.
William Dunlop was victorious in the 250cc race by 0.71s from Sweeney with John Ella third.
Michael Dunlop won the Senior Classic race from Robert McCrum, with Guy Martin finishing fourth.