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Discussion Starter #1 (Edited)
I see some nice improvements in the GT4 suspension. I'm surprised know one has asked the obvious yet....... "Hmmm, what can I retrofit?"

Fully recognizing this is a bigger challenge than retrofitting Cayman R supension parts onto a Cayman S, has anyone have any experience with putting 981 GT4 suspension parts on a 987? I'm interested in reading your experience on retrofitting any or all of the following:

  • Dampers
  • Lower Control Arms [wishbones]
  • Tensioners [control arms]
  • toe links [track rods]
  • Cooling ducts
  • Uprights [wheel carriers]
  • Sway bars [stabilizers]
  • Subframes [side sections]
  • Sensors
  • Control modules

Naturally the 981 cars [over a 987] are a candidate for a retrofit, but I'll let someone else ask that question in the 981 modding forum. So lets leave this thread to putting GT4 parts on the 987s.

I'm attaching the relevant GT4 PET part pages for everyone to pick apart.
 

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Don't you also need different hubs and axles and likely several other parts too? Sounds like an EXPENSIVE proposition to me, you'd probably get 90% of a GT4 suspension with a really good 987 suspension setup at a fraction of the cost. Still, I agree, it would be an "interesting" project.
 

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Why would you want to do that? The 981 is a completely different car to begin with and shares very little common parts with the 987 cars. The GT4 is even a further gap. The damping rates to begin with not make sense, not to mention all the other variables including suspension travel and other various ratios.

You could easily create your own 987 GT4 anyway. Just slap on B16 Damptronics with custom spring rates/damping rates if you get really fancy. Change the PASM module to TPC (probably more active than GT4's system). Then swap all the relevant lower control arms with 997 GT3 ones. You could easily get hold of other control arms from other manufacturers. GT3 + tarett sway bars would do the job. Then of course do your own toe links as there are a few adjustable links you could find.

It makes no sense to try to shove 981 parts into a 987, and even less so when trying to shove GT4 parts down -- which probably won't even fit. TPC also was working on a strong subframe if you are interested. I'm not sure how far that project went. And why change the carriers unless you are looking to retrofit PCCB calipers around all corners or front GT3 calipers? I just don't get it ...
 

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Naturally the 981 cars [over a 987] are a candidate for a retrofit, but I'll let someone else ask that question in the 981 modding forum. So lets leave this thread to putting GT4 parts on the 987s.
I don't even think retrofitting that rear suspension onto a 981 is feasible. They had to substantially rework the frame there I think to make room for it.
 

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Discussion Starter #7
I tend to agree with you, yeah, it does not make sense. I'm curious if someone has put these cars side-by-side and studied.... Here are some examples of reasons for a swap.

1) a good fitting porsche brand rear brake duct is not available for the 987
2) the uprights on the GT4 appear to be engineered to lower the car without messing up the roll center and handling. [unlike problems introduced by lowering springs and off the shelf generic coilover kits.]
3) porsche dampers on the gt4 appear to be very well engineered. [If the motion ratios f/r are the same on a 987 and 981 this might be a great upgrade.]
4) because we can. Obviously it has been a long tradition in the porsche community to upgrade cars with "newer/better" model parts. If it fits, I'm sure someone will retrofit it. I'm guilty of this: I have the following on a CS: GT3 Front LCAs, GT3 Master Cylinder, GT3 Shifter, GT3 Front Brake Ducting, Cayman R rear swaybar, Cayman R dampers/springs and Cayman R Front Brake Pads.

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I think these are pretty much the only parts from a GT4 that could easily be retrofitted onto a 987. A 981 may be a different story. Of course with enough time and money, all things are possible....

Screen Shot 2015-08-12 at 10.34.57 PM.png
 
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I'd like to see a side by side test between a stock GT4 and a fullymodded 987.2 CS or CR (aftermarket/GT3 bolt on suspension bits, brakes and modded motor - 3.8) with a pro driver like Randy Pobst at Laguna or Willow. I'd bet the times wouldn't be that far off. it's expensive enough modding just with good bolt on stuff. I'd look at one of those GT4s on Ebay right now for 20-30K over MSRP before trying to turn a CS/CR into a complete GT4 clone. After watching that video TPC did it's pretty clear nothing GT4 is going to fit!
 

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It's generally not that hard to have modded cars to "beat" higher model cars in stock forms. It really boils down to preference, reliability, taste, resale value and overall "balance". I'm pretty sure plenty of heavily modded 987.2 CR would give a stock GT4 a hard time.

Anyway, PAG spent a lot of time sorting out these cars. Even the roll centers seemed to have been corrected, while a regular CR actually doesn't seemed to have that done at a bespoke level even though the car's some 20mm lower than a standard passive suspension Cayman. On top of that, there is a lot of stuff going on under the car. Even something simple as the tires aren't the same. Regular Caymans are much more like tractors with rear tires considerably higher / bigger (around 3%+) in diameter than the front ones. However, look at the GT4 tire sizes and suddenly the car isn't really like a tractor anymore.
 
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