The pair put in the blistering laps before track temperatures dipped dramatically in County Down, resulting in both riders slipping off.
But with nothing worse than some broken bodywork to their GSX-R1000s, it was a successful outing for the team.
"The second day has been quite productive again, even though we probably only had half the time out there compared to yesterday," Brookes said.
" Yesterday's conditions were freezing and today's were even worse but we've been able to match my lap times which indicate the bike is heading in the right direction.
"The weather prohibited us from getting any further on, but taking it into consideration, we did really good. For me it has shown that we have been able to push the bike close to its limits already, which is pretty impressive for a first test, and we both only got caught-out at the end because of the weather."
Jacobsen added: "Everything was working great today up until the crash and as Josh says; we just got caught out with the weather."