Slater has previously masterminded victories in the Bathurst 1000, Bathurst 12 Hour, and 24 Hours of Daytona.
The first two of those came at Tekno Autosports, where he returned (then as Team Sydney) last season after a stint in the United States.
Slater has been recruited as Nick Percat's race engineer on WAU's #2 ZB Commodore.
The 2011 Bathurst 1000 winner had enjoyed a successful relationship with Andrew Edwards at Brad Jones Racing, but when Edwards was snapped up by Triple Eight Race Engineering, WAU set about finding the perfect new foil for Percat.
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“We're super excited to have Geoff join the team,” WAU team principal Bruce Stewart confirmed to Speedcafe.com.
“We have recently acquired Nick to come into the team and it's great to partner Nick with a really respected, experienced and credentialed engineer like Geoff, who has got experience not only in Supercars but in international formats.
“And he also seems like culturally he would be a really good fit for our business.
“It makes us stronger, and that's really exciting on the edge of the 2022 season.
“It's important that we have two strong cars, because we expect to be fighting for race wins and championships, and to be in contention in that respect.
“So to do those things, you need to have two strong driver/engineer pairings and I think Geoff seems to have the right personality and demeanour that will really work well with Nick and mean that they will be a really strong pairing.”
Percat's predecessor Bryce Fullwood had worked with a number of race engineers, primarily Terry Kerr but also Rob Starr, head of performance Grant McPherson and technical director Carl Faux at different points.
“Terry played an integral role at Bathurst and he will continue to play an integral role going forward, so nothing changes insofar as he is an essential member of our team,” said Stewart.
“Equally, Robby is a legendary hero of our team for over 28, 29 years and he runs our subassembly department but also subs in and does a lot of work for us at race tracks when needed.
“And I don't expect that will change, particularly when you look at potentially COVID interruptions and how you have to be nimble with your staffing, I think this can only make us stronger.”
Pressed further on the advantage of such engineering depth, Stewart added: “I think equal to their individual abilities is the way that they can collaborate.
“They work really well together as a unit, the egos are minimal and the collaboration is really impressive and awesome.
“So, from my point of view, it's just great that they run that part of our business and make the decisions and take us forward.”
Triple Eight and Dick Johnson Racing have also locked in their engineering line-ups, while Stephen Grove has previously confirmed both Alistair McVean and Dilan Talabani are staying on with his Grove Racing squad in 2022.