Fast work

Fast work
Repaired panel shows original twill weave and the plain weave repair section. Note Tridair fasteners at the panel’s edge. (Photo: Graham Heeps)

Motorsport professionals are at the cutting edge of fixing damaged vehicles.

It’s Friday practice at Daytona International Speedway, where sportscar race teams have gathered for the weekend’s Rolex 24 at Daytona. At Ford Chip Ganassi Racing, which will field two Ford GT LMs in the 24-hour race, an off-track excursion results in damage to a number of composite side panels on the Multimatic-built machine.

The biggest problem concerns the place where one of the Tridair fasteners, which hold the outer panels onto the underlying structure, has been ripped out. Handling the repair is John Worth, a composite specialist at Ganassi, who looks after the GTs’ body panels both trackside and back at the shop in Indianapolis.

“We were short of time,” Worth tells Collision Management several hours later. “At the shop we’d have done a nice layup under there with new carbon. We’d have re-drilled the hole, glued the bucket to hold the fastener back in, and reinforced everything. Here, I did something similar, but to speed it up I drilled a hole in a flat piece of stock carbon—we get all kinds of scrap from cutting things out—glued it up underneath and riveted it in place. With more time, the glue would have done the work without the rivets. I then glued in the bucket to hold the fastener.”

Improvise, adapt, overcome

The ability to improvise is a key skill in composite repairs, especially when there’s no auto clave to hand.

“You’re not always working to aerospace standards,” says Manny Martinez, who repaired composite race car parts for Swift Engineering and Porsche team, Alex Job Racing. “If you’re making a car part and it’s not extremely structural—you’re just holding a fender in place for example—then you can improvise. You learn that as you go.”

“We can’t use pre-preg here at the track because we don’t have an oven to cure it, but for an emergency repair we would do wet layup,” adds Worth. “We carry a vacuum pump and bagging system that applies around two atmospheres of pressure. We also use a mixture of slow and faster [curing] resins so that we can dictate the speed of the cure.”

Moulds are generally unavailable trackside, so for a splice—probably the most common repair that he handles—Worth might use a fast-acting adhesive to get the part to hold its shape. He could then use wood or another piece of carbon on the outside to help it maintain that shape while a layup is done on the inside. If it’s not possible to bag the part, then peel ply can be added to a wet layup to wick out the extra resin.

Unconventional equipment

That race-honed creative thinking can apply back at base too, and there’s a lesson here for those that repair high end production cars, too.

At his repair shop in Miami, Martinez created a low-cost, home-made autoclave that’s the size of a 55-gallon drum.

“Technology has moved on and more materials are readily available,” he says. “Pre-preg cloth can be used for room-temperature cures, or you can activate it with a heat lamp. A heated paint booth could be used to lower the cure time, and I’ve seen guys use a small walk-in oven to cure parts quickly, too, instead of an autoclave. Sometimes at the track, all we had was a heat gun and the sun, but we did what we had to do to make it work.”

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