With our revolutionary Stage 2 Rear Top Mounts, you can fit 991 GT3 RS-width tyres to a Porsche Cayman GT4, GT4 RS and Spyder RS.
Last year our Porsche Cayman GT4 went head-to-head with the mighty 992-generation GT3 RS at Spa-Francorchamps. Our Circuit Handling Pack allowed the GT4 to generate extraordinary amounts of cornering grip around the Formula 1 circuit, and the Cayman ran the 3RS very close for outright speed and even trumped it for driver enjoyment.
On that last point, pro driver Leyton Clarke (founder of RMA Track Days and owner of the 992) thought the GT4 was a more enjoyable steer around large sections of Spa than his own GT3 RS!
The unforgettable experience of lapping the iconic venue left us eager to find even more speed in our GT4. That naturally led us to reassess tyres sizes.
Porsche Cayman GT4 Rear Top Mounts
As standard, the GT4 runs tyres size 245/35ZR20 at the front and 295/30ZR20 at the rear. As our GT4 was already equipped with Suspension Secrets camber and caster plates on the front axle, it was immediately possible to fit wider 265/35ZR20 tyres on new Bola wheels size 20×9.5J ET49 (5×130).
However, the rear of the car presented a bigger challenge. The Porsche Cayman GT4 rear top mounts sit on top of the shock absorber assembly and are accessed from inside the boot area as well as from within the wheelarches. The stock 295-width rear rubber is already running the wheelarches pretty close and rubbing will occur with even just a modest increase to 305-width tyres without suspension modifications.
It is possible to dial in more negative camber on the rear axle of a standard GT4 using camber shims. However, there is still insufficient room for wider tyres even with the slight increase in headroom created by the increase in negative camber.
This is the type of engineering problem we love solving at Suspension Secrets. We are better placed than most to offer a solution because we design, prototype and manufacture all our parts in-house in the UK. We know Porsche owners around the world would love to run wider rear rubber on their GT4, GT4 RS and Spyder RS. This inspired us to begin development of entirely new parts – rear top mounts that offer increased camber adjustment and the possibility of fitting much, much wider rear tyres.
GT4 Suspension Upgrade
To make this dream a reality, we designed our Porsche GT4 rear top mounts to raise the damper bearing up and inside the car. This provides much more clearance for the damper to pass through the chassis in an even more aggressive offset position than any other option on the market. And it retains the standard bump/droop ratio of the OEM damper. That’s no easy feat and it’s a design we are hugely proud of.
Following extensive prototyping, we have developed two versions of our GT4 rear top mount. The Stage 1 parts allow fitment of 305-width rear tyres. The more extreme, two-piece Stage 2 design supports the fitment of 325-width rubber with 20x12J ET45 (5×130) wheels.
With regard to the 325 option, despite a massive 30mm increase in tyre width over stock, no bodywork modifications are required on the GT4, GT4 RS or Spyder RS. Our GT4 rear top mounts also work with OEM dampers, as well as aftermarket coilovers from manufacturers such as Moton, Nitron, Öhlins, AST and MCS that use the stock top mounts for fitment. This makes our product a world first.
Road & Track Testing
Before launching the new parts to market, we put our new Porsche Cayman GT4 rear top mounts under extreme pressure during comprehensive road and track tests. On hand were former Alpina works driver Chris Dymond and racing veteran Leyton Clarke who showed the rear top mounts no mercy, rattling kerbs and really leaning on the GT4’s upgraded suspension through high-speed sections of premier UK racing venues.
The result was more cornering G-forces achieved than ever before, and an even more intoxicating driving experience. On Donington Park’s GP track, our GT4 achieved 1.785G on the way to an impressive 1min 39sec lap time despite sub-optimal track conditions. This was a whole three seconds faster than the Cayman’s previous best lap.
After time in the hot seat, both drivers likened our GT4 to a full-blown 991 GT3 RS in terms of how it gripped through corners, which is very high praise indeed.
Handling Benefits
Fitting wider tyres dramatically improves handling performance. A larger tyre contact patch means your Porsche is able to transfer its power to the road more effectively. This boosts acceleration and traction on corner exit. Fitting wider tyres also improves braking performance because even more friction is generated between road and rubber. This means you can brake later into corners to the benefit of lap time. Stability is also enhanced thanks to the widened road stance.
If you want to unlock a new level of handling performance from your Porsche, full details on our Suspension Secrets Rear Top Mounts can be found below…
Porsche Cayman GT4 Rear Top Mounts
Circuit Handling Pack Kinematics Kit
Porsche Cayman GT4 RS Rear Top Mounts
Circuit Handling Pack Kinematics Kit
Porsche Spyder RS Rear Top Mounts
Circuit Handling Pack Kinematics Kit
