WHAT’S IN THE WORKSHOP – FLO-GINEERING

What’s in the Workshop – Flo-gineering – Photos: Supplied

Regular attendees to historic events would be familiar with the name Carey McMahon, the engineer has competed both here and abroad in a variety of machines, however his current project has been a labour of love.

By HEATH McALPINE

“I’m screwing the fuel injection in while we’re talking,” McMahon laughed as he detailed the project to Auto Action.

The latest acquisition to McMahon’s racing stable is the Chevrolet Monza that was raced by Graeme Whincup (yes, the uncle of Jamie), who along with John Riordan built the ultimate Sports Sedan in 1985.

“It’s an engineering piece of brilliance that they’ve done,” McMahon proclaimed.

Featuring a variety of innovations, this Monza was raced previously by a range of drivers including Whincup and Steve Voight before being purchased by Peter Champion to be displayed as a replica of Bob Jane’s similar car of which Peter Brock drove in 1982.

The extent of work that was needed to the Monza failed to reveal itself until it was stripped right down to a bare shell.

“We acquired and thought we’d do a restoration on the Monza,” McMahon explained. “With any of these projects, when you pull them apart and you get down, you see all the details of the condition that each component is in, it’s only then you realise what works involved.”

“We’ve reconditioned everything, I mean went back to a completely bare shell and if we couldn’t pull it off the car like it was with the aluminium panels around the whole chassis we’ve polished.

“Everything that we were able to take off we’ve renewed; the engine is almost completely new because each part was worn out except for the heads and manifold. Everything below the heads is new.

“That was a big project.”

The clear aim during the Monza’s build process was lightness and this stretched right down to the engine where mounts were discarded in favour of using the bellhousing mounts to bolt the unit directly to the chassis. Machining also carried through to the engine internals, while new pistons, rods, camshaft, lifters and crank replaced the tired original components.

But the weight reduction had a detrimental effect on the 35-year-old block when it came to piecing the components back together.

“When we were assembling it, we were putting the main bearing caps in and torquing them down waiting for the click, but when we thought it was going to happen there was this really loud crack,” McMahon recalled.

“We took all the bearing caps off, pulled the crank out and it split the block from the crankshaft area down to the camshaft area.

“The block was 35 years old and it just gave up.”

Significant restoration hours have been put into the suspension, a system designed and built by Ron Harrop. McMahon marvels at the design, which consist of rear inboard shocks, top wishbones that act as rocker arms and uprights all hand fabricated.

“It’s quite an ingenious design,” McMahon emphasised.

“We’ve renewed all of the suspension, we’ve stripped it, either blasted or acid-dipped it, crack tested everything, we found a few cracks and welded them up.”

“We’ve re-nickel plated all of the suspension like it was back in the day, it looks like chrome really. All of the steel work that holds all of the engine and transaxle on, we’ve stripped all of that and then powder coated that back to a nice grey, anything that was metal either got plated or anodised just to restore it.”

Just like the engine, the transaxle required a complete overhaul as well.

“The magnesium transaxle casing was in very poor condition as was the rest of the transaxle due to 35 years with minimal servicing,” McMahon said.

“We re-machined the whole inside of the transaxle. Each bearing we put a sleeve because they were loose and rethreaded each thread because the magnesium degrades over the years. Then we re-dichromate plated the transaxle back to how it originally was to a charcoal colour.

“That’s been completely redone and rebuilt internally.”

Working alongside Nigel Bollings and Rod Starr five days a week, McMahon is aiming to have the Monza completed by August ahead of a hoped racing debut at Morgan Park’s historic meeting in October where it will contest the Group U class for Historic Sports Sedans.

“I’m really keen to have it ready for that, but when I say ready it’s not just rebuilt, I want to have the car tested, tuned and make sure we’re happy with it before we go racing,” explained McMahon.

Reflecting on the engineering features within the Monza, McMahon was surprised how far Whincup and Riordan pushed the build to the limit to reduce the overall mass.

“Graeme really wanted to build a lightweight car,” McMahon emphasised. “It weighs under 1000kg.

“The engineering they put into it, the bolts are all lightweight, the whole way they built it, it’s strong, but right on the limit. If you were building a car, you’d probably think it needs bolts that are bigger than what you need just to give a bit of confidence, there’s none of that.

“I love the engineering side, as it’s my profession, it’s my form of art to make something stronger, lighter, faster or functional. I really enjoy that side of it and that’s why I go to so much trouble.”

Importantly, Whincup is keeping an interest in the build. He is aiming to fly up for the Monza’s maiden test since the restoration, he has even contributed to the restoration by producing the stickers and team merchandise.

Not only that, but his seven-time Supercars Championship winning nephew is also keen to have a run in the old beast as well.

“He told me that Jamie wants to come out and have a run in it when we have a test day,” said McMahon. “I look forward to that.”

Outside of the Monza, further development work has gone into McMahon’s Group S De Tomaso Pantera, particularly with the gearbox. Although fast, the Italian machine coupe has been fragile, but a new ZF gearbox that has had second, third and the selector fork redesigned is hoped to cure the problem.

The new gearbox, re-worked suspension and re-freshened engine will get its first test at Wakefield Park in August.

As for McMahon’s Sierra, it remains in Europe after he contested a variety of events at Brands Hatch, Oulton Park, Silverstone, Spa and Portugal where it suffered damage. The B&H Sierra has been repaired in the UK by noted expert Paul Linfoot and should be on its way back to Australia in November.

As racing gets back underway, What’s In The Workshop will continue albeit in a staggered manner.

Also for more of the latest motorsport news pick up the current issue of Auto Action. Also make sure you follow us on social media Facebook, Twitter, Instagram or our weekly email newsletter for all the latest updates between issues.