AQM/OCD
GT4 Multi Link Rear Suspension Kit

(Patent Pending)

Background

Unlike the 911, the Boxster/Cayman platform was designed with strut front and rear suspension (mostly to reduce costs by recycling the front suspension parts at the rear).  Although the GT4 has a unique rear upright compared to other Caymans, it is still a strut design and is inherently flawed in suspension geometry compared to that of the 911 platform that has been utilizing Multi Link Rear Suspensions. Common complaints when exploring the limits of the GT4 include instability under hard braking, lack of nimbleness/turn in, and lack of confidence in rear grip (especially in high speed corners). As we consider the GT4 to be the finest example of the Cayman platform to date (and superbly fun to drive), we decided it was time to even the playing field between the Boxster/Cayman and 911 suspension geometry.

We collaborated with renown Formula One/Le Mans/IMSA engineer Jay O’Connell of O’Connell Car Development (OCD) to research and design a Multi Link Rear Suspension Kit for the GT4. Over a period of about 18 months of initial R&D at Grattan, Mid-Ohio, and VIR, followed by several thousand miles testing durability on Road America and Sebring, we released our patent pending GT4 Multi Link Rear Suspension Kit to our client base in 2017, and have seen extraordinary improvement and nothing but exceptional feedback from the owners of over half a dozen GT4’s running our system, and now two Clubsports as well.


How It Works

The GT4’s rear struts are converted to a Multi Link by decoupling the damper from the upright and replacing it with two upper links similar to the layout of the 997 RSR rear suspension. The links were attached to the upright and the chassis using stiff bolt-on brackets that position the links around the stock exhaust, and the toe links were shortened 3" to work with the shorter upper links and stock lower arms. This allows us to achieve our target geometry including: camber curve (rear view), toe curve (top view), wheel center (side view), and roll center. As it is a complete bolt-on kit with no welding required, it is also REVERSIBLE in the event the owner wants to put the car back to stock.
 



Results

 
  • More camber: By inverting the camber gain curvature, our Multi Link geometry achieves significantly more negative camber in bump and roll compared to the strut. This allows for 2.5 degrees more negative camber at full bump and 0.9 degrees more negative at 3 degrees of roll.
  • Less roll understeer (only 1.2% as compared with 8.4% stock).
  • Minimal toe out during rebound.
  • Higher/consistent roll center height (46 mm higher than stock and no longer drops in roll).
  • Anti-geometry similar to stock with slightly more anti-squat (120% instead of 108%) and slightly less anti-lift (54% instead of 58%).
 

Driver Feedback

 
  • Much better high speed cornering confidence, due to the increased camber gain and roll center stability.
  • More low speed agility due to the higher roll center.
  • Greatly improved stability during hard braking due to less toe change in rebound.
  • Average lap time improvement of 1 second per minute.

Conclusion

Our Multi Link design has successfully replaced the stock GT4 rear strut suspension, and has exceeded the goals set for suspension geometry comparable to that of the 911 platform. The parts have transformed the limit handling such that owners prefer driving the GT4 instead of their GT3 (for those that have both).

Pricing/Install

Our Multi Link Rear Suspension Kit is available for purchase through us directly at $8000 (parts only), which includes a core swap for our modified uprights. Installation takes two full days at our facility. If the vehicle cannot be dropped off or shipped to us due to location, we will work with you to determine the best alternative for an experienced installation, as well as the required suspension geometry and chassis tuning.

Contact Information
 
Please feel free to email/call me at my contact information below with any questions or inquiries. It would be a pleasure to work with you to meet your goals, and have you join the growing AutoQuest community : )
 
John Gaydos
Cell: 484 883 6197 (text available)
Work: 239 432 1700
Email: john@autoquestms.com
 

Let's Chat : )

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