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 ahigh 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 occur in OEM rear arms and again, dynamic alignment change follows. Solution? GMS performance rear arms with preinstalled GMS ball joitns 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.
Available in SPORT or RACE version, so which should I choose?
If you are occasional tracker and aggressive street driver, "SPORT" option is the one to go for. Zero flex up to 2.3G (the longest side of triangle still carries the most of stress, but due to better material and additional reinforcement gussets, this type of arms are more than 50% more rigid than stock rear arms). Still noticeably more rigid than OEM rear arms and no undertray mod required. Recommended for high grip street and medium and hard compound semislick tires (UTQG >40).
If performance is the only factor, than "RACE" version is the one to go. Zero flex up to 3.3G (the longest side of triangle is now exposed to much less stress due to perpendicular reinforcement tube splitting the effective length of it and having additional reinforcement gussets and better material this type of rear arms are 107% more rigid than stock rear arms. This are the most rigid rear arms available on the market, providing the most precise handling with zero dynamic alignment changes. This upgrade requires minor modification of rear undertray on cars with newer, curved undertray design (slight cut in the aluminum undertray). Recommended for wide (+280mm sectional width), soft compound (UTQG <50) slick tires.
ALFA ROMEO - 4C - Performance rear arms
- Unmatched handling precision
- Unmatched rigidity
- Unmatched durability
- More than 50% rigidity increase for "sport" version and 107% rigidity increase for "race" version
- Zero flex or up to 2.3G for "sport" version and 3.3G for "race" version
- 600g lighter per set than OEM for reduced unsprung weight
- Aircraft grade, 25CrMo4 / 4130 alloy, laser cut and CNC milled tubes for perfect fit during welding process
- Superior strength, ductility and resilience material properties
- Hand TIG welded by certified 6G and 5G welder
- The only uniballs and ball joints on the market made of CrMo and PET-GL material for unmatched durability, friction free movement and ultimate precision
- Maintenance free
- Sold as a set (1x left rear arm + 1x right rear arm)
- Incognito black electrophoretic coating
- Fits all Alfa Romeo 4C Coupe and Spider models