|Specsavers County Championship Division Two, 1st Central County Ground|
|Glamorgan 335 & 307-6: Lloyd 102*; Briggs 2-62|
|Sussex 552-5 dec: Wells 181, Brown 159*, Joyce 106|
|Match drawn - Sussex 11 pts, Glamorgan 9 pts|
Sussex's victory bid was frustrated as David Lloyd's unbeaten hundred enabled Glamorgan to bat out the final day.
After three wickets fell in the morning, Lloyd made 102 not out, with a six and 14 fours, supported by Aneurin Donald (44) and Jacques Rudolph (38).
Stu Whittingham (1-58) and Danny Briggs (2-62) were the pick of the Sussex attack on a placid pitch.
The teams shook hands on a draw at 17:20 BST when Lloyd reached three figures.
Sussex looked in with a strong chance when Will Bragg was run out just before lunch for 33, after nightwatchman Owen Morgan (36) had earlier been bowled by Briggs.
But they took just one wicket in the afternoon, and Lloyd was dropped at slip on 66 off Whittingham when the home side took the second new ball.
Sussex remain in the lower half of the table despite remaining unbeaten, with one win and seven draws.
Glamorgan have been unable to win a Championship game in the first half of their season, but do have a successful limited-overs campaigns to focus on - and they will meet Sussex again, in the T20 Blast, in Cardiff on Thursday.
Sussex captain Luke Wright told BBC Sussex:
"It was a tough four days but I am really chuffed for the guys, particularly with the way we batted. We've not scored enough big runs, and to see the guys get big hundreds is exactly what we are looking for.
"It was always going to be difficult. The wicket didn't really turn, we kept flying in and tried everything, but credit to Glamorgan for holding on tight."
Glamorgan top scorer David Lloyd told BBC Wales Sport:
"It was a big challenge, we lost an early wicket but the way the boys turned up today and occupied the crease was really good, so to come away with a draw is excellent.
"I tried to bat time but also to bat positively as well so as not to die in a hole - the way Aneurin [Donald] played his shots, it rubbed off on myself as well so we just had to make sure it was the right ball to put away.
"I didn't have a choice [about staying on for his hundred], I thought by the field that Sussex set, I had one over to get it so that's what I tried to do.
"We've had a good start in both white-ball formats and the T20 is the one we're really trying to target after the start we've had, so hopefully we can keep it going at home."