The StopTech EVO X continues to take the Street AWD Class by storm, this despite a few teething problems. However, these issues show just how fast and well-sorted this amazing machine is. They started the weekend hoping to prove that they had the durability they needed from the internal waste gate on the latest version of their Garret direct bolt on turbo, which had proved to be such a problem at the Willow Springs event. They were also testing for the first time their new Cosworth head and cams installed by Mike Keegan. The StopTech EVO X uses a COBB Tuning AccessPORT and the team tunes the car themselves using AccessTUNER Race tuning software in order to get all of the performance modifications working together at their best. Stephen Ruiz, the driver of the EVO X and tuner at GMG/ITG said, “Every change tried on the engine is tested and then tuned using the Cobb Tuning tools.”

Unfortunately, as soon as the car was up to speed they encountered what turned out to be a slipping clutch. With a slipping clutch, the team went into survival mode for the rest of the weekend then only able to make about three laps each time out before the clutch slipping would be a problem. The team went through the whole weekend only running 3-4 laps of practice but it was enough to make the small changes needed to dial-in the car’s handling. On the morning of the race, the EVO was lapping the course fast enough to be in the lead Street class group and “qualified” fourth. The way that the timed segments are run, that would be the team’s starting spot for both sessions and being back in the pack would hurt when it really counted. In the first session, the EVO was second fastest in AWD class and third overall. To conserve the clutch, the team skipped more practice which was cut short anyway due to time running out with a lot of cars having to be retrieved from on-course. Finally, in the last session, the team pushed as hard as they could. While the EVO was much faster and in fact passed two cars that “out qualified” it on the second lap, the StopTech Team scored second in AWD Street class and second overall with a 2:34.868. In the end, first place was lost to having to pass slower traffic and, of course, the clutch started to slip again on the third and fourth laps.

Since the event, the engine and clutch have been removed for repair and inspection. The driven disc and surfaces of the pressure plate and flywheel looked almost new. When the clutch cover was tested, which was the same since the clutch was upgraded to an ACT unit, the clamping force was found to be about 10% low, but the bottom line was that the new puck style driven disc was not broken-in properly before the problem was noticed. It was later discovered that had the they driven harder on the slipping clutch, it would have broken-in properly and worked the way it was supposed to.

That is always a challenge – to break parts in quickly on a car that sees use only on the track. They needed a fast break-in procedure for a new solid disc clutch type. The Stoptech EVO X team has now installed a blueprinted version of the clutch cover with higher clamp forces and a different solid disc design. Initial testing shows it to be working correctly after some controlled break-in “slip” cycles and the team can’t wait to get out to the next event at California Speedway on November 14 and 15.