From the very beginning of its launch, the Alfa Romeo 4C is a subject of poor handling reviews from journalist and users. If you have ever wondered why your 4C has all the potential of a high performance car, fully carbon monocoque, excellent power to weight ratio, looks like a supercar, but it drives less so, here is the answer.
 
Design of the rear arms of 4C in conjunction with stock soft rubber bushings is not engineered adequately for performance driving high lateral G forces. Under cornering, acceleration or braking, rear arm rubber bushings cannot withstand the forces transferred from tires to the suspension and rear arms, so they flex, which causes a significant dynamic toe changes and therefore the rear end of the car feels floaty, disconnected and unpredictable at the limit. The more grip the car generates, the more noticeable the problem gets. Replacing stock rubber bushings with GMS uniballs solves the flex in rubber bushings, but as the flex cannot occur in the uniballs, it does now occur in OEM rear arms and again, dynamic alignment change follows. Solution? GMS performance rear arms with preinstalled GMS ball joints and GMS uniballs. The next level handling upgrade.

GMS performance rear arms are CAD designed and made of quality 25CrMo4 / 4130 alloy tubes, providing superior strength, ductility, resilience and low weight. They are precisely TIG welded by the hands of certified 5G and 6G welder into the state of art performance part. This upgrade provides reduced unsprung weight for better suspension response, utilizes GMS uniballs and GMS ball joints for extreme durability and handling precision and provides reduced flex for further improved handling precision and feedback. GMS performance rear arms are electrophoretic coated to achieve the unique incognito black finish and prevent corrosion and deterioration. Beneath, there are state of art TIG welds in its renown colorful patterns.

With stock rear arms and stock rubber bushings especially, the factory had to dial in a lot of static toe-in to compensate for dynamic toe changes and prevent toe-out, most noticeable over bumps and nose dive while braking. GT3 race cars run between +0°05' to +0°12' of rear toe-in per wheel and stock 4C runs about +0°20' per wheel. By having more rigid GMS performance rear arms, we are now able to run less toe-in at the rear and get much closer to GT3 alignment specs, which makes the car feel more neutral, less snappy on the edge and makes the car transfer to oversteer more fluently and tire wear and temps are decreased as well. With GMS performance rear arms, we are one step closer to making 4C chassis really shine and provide that outstanding feedback that Lotus car have always have been praised for and Alfa Romeo 4C was always missing.