A $3000 shock absorber that can be bought off the shelf is the stunning secret weapon Ford is using to bring an end to Red Bull Racing Australia’s V8 Supercars reign.

Jamie Whincup has been an ­unstoppable force for the past four years, but Prodrive Racing Australia’s Mark Winterbottom is leading the charge this season.

A Daily Telegraph investigation into claims Prodrive Racing has an unfair aerodynamic advantage has revealed an Australian-built shock absorber that can be fitted to a street car is the real reason for Winterbottom’s stunning speed.

Prodrive boss Tim Edwards on Monday night admitted a bold gamble to drop the industry- standard shock absorber built by SACHS and replace it with “the cheapest shock’’ on the market has helped the team win nine of this year’s 17 races.

“Just about everyone in the field uses the same shock,’’ Edwards said. “We realised we weren’t going to get ahead by following the leader so we decided to do something different — and it looks as though it’s worked.’’

Winterbottom is banking on the “Supashock’’ as he chases his first championship.

Data obtained by The Daily Telegraph showed the four Prodrive cars are performing better than their rivals while cornering. The Holden cars remain quicker in a straight line.

Further investigations revealed the DJR Team Penske Falcon was not performing as well as the four Prodrive Falcons despite being aerodynamically identical. The only difference between the Fords was the brand of shock absorber being used.

media_camera The shock absorbers Ford is using.

“It is certainly a difference between our cars and the others,’’ Edwards said.

“Is it the be all and end all? Who knows? But it has certainly made a difference. We’d like to think we’ve helped developed a pretty good product and that it has helped.’’

Edwards said the team decided to move to the Adelaide-built shock absorber this year after 18 months of development.

The man responsible for the ­Supashock — which has “thrustshaft’’ damper technology — is former V8 Supercars engineer and data expert Oscar Fiorinotto.

“It is the cheapest shock on the market and anyone can go and buy it,’’ Edwards said. “We made the decision to go full-time with them this year and we are solely focused on the Supashock.

‘‘We have done 18 months of hard work so it’s not just a case of bolting it in. A lot of hard work has gone into it.’’

DJR Team Penske has also moved to the Supashock Racing Suspension system following Prodrive’s stunning season start.

Erebus V8 also uses the shock absorber that Edwards hoped to keep a secret.

“Look, there is no silver bullet,’’ Edwards said. “People can go and get this now but it’s a combination of a thousand things.’’

V8 Supercars has denied Prodrive has an aerodynamic advantage because of the new shape of the FG-X.

Winterbottom leads the championship by 248 points heading into this week’s Queensland round.

• Tune into Fox Sports 5 on 506 from 7.30pm on Tuesday night for another James Phelps driver shock on Inside Supercars.