I have tried to look up the spring rates for a 2015 Cayman GTS with the X73 Suspension and I haven't been able to locate any accurate information. I keep getting conflicting information. I even tried a search on this forum and I keep getting unrelated topics. I would appreciate any help that you can provide in regard what are the GTS spring rates. I would appreciate if the info would be in pounds per square inch since I am not an engineer or a math wizard and the various metric conversion charts are essentially useless too. Thanks

Kenny Mitchell
nokones@kenmitchell.com

 

x73 is the same on a GTS as an S.
https://norwestsuspension.com/convert-spring-rates

 

Thanks for responding. I did see that chart posted and the GTS model was not listed. It is my understanding that the spring rates are stiffer for the GTS. I believe the GTS spring rates with the X73 suspension may be around 80 n/mm front and 90 n/mm rear which puts the springs in the area of a 4XX pound front spring and in the area of a 5XX pound rear spring. Its unbelievable that this information is a secret and not available.

Kenny Mitchell
Nokones@kenmitchell.com

 

Pretty sure they're the same. You can order the x73 kit from Porsche and there's no specific PN for GTS cars, only PDK or nonPDK. Check out the PET at realoem.

 

Yep my understanding was that GTS just uses the generic PASM spring rates found in base, S and GTS. Or if it has S PASM it uses those spring rates. Nothing is GTS specific, just an S with all the options.

For your interest Ohlins R&T for 981 is 70 front and 80 rear, Ohlins Dedicated Track is 110 front 130 rear. Tarett 981 spring upgrade is 79 front and 88 rear so closest to what you are looking for?

So X73 is still quite soft.

 

Thanks for responding with the information.
I've been in contact with Tarett and we've been discussing both the JRZs and the Ohlins. I also been in contact with Small Fortune Racing regarding the MCS double adjustable non-remote reservoir shocks with adapters to accommodate the factory springs, and Mike Maier, Inc. regarding JRi shocks. I've been told stay from JRZs for autocrossing and that goes for the samething with Bilsteins. Not sure why on the JRZs but, I know that the Bilsteins will not transition very good and are sluggish in the slaloms.
Maybe I should have posted what my intent is in my original posting.
I intend to autocross the car in PCA and SCCA events and keep it near as stock and grocery getting as possible. I plan on buying some Forgeline wheels and more than likely will run the Michelin Pilot Sport Cup 2 R tires. I think the 110/130 spring combo would be waaaaaayy tooooo much for just an autocross car on essentially a soft compound street tire. I think the 80/90 combo probably would be my best choice and Tarett also agrees with it.
Both MCS and JRi are looking into developing shocks without remote reservoirs for the 981. It appears that the rears are the complicated end because of the clearances and the heat from the nearby exhaust system, and the bottom of the factory rear spring seat design is why there are no off-the-self choices.

Maybe I need to have some patience and see what will MCS and JRi will come up with.

Kenny Mitchell
nokones@kenmitchell.com

 

Fwiw, you can't change springs in SCCA Street class. If your purpose is to keep it sane on the street and autocross, that's probably where you want to be.

 

I am fully aware of that. I am trying to get shocks so I can use the factory springs and as of today,, those shocks do not exist.. It is very possible that they may exist at the beginning of the year.. If it comes to the point where I can't use the factory springs than it will be a PCA only car. I have two other cars that I autocross in SCCA anyways.

 

Hmm, SCCA Street Touring U class could be an option with aftermarket springs and camber plates. The car may be very competitive in STU. I may just gave that idea some serious thought.

 

I can guarantee you that the X73 springs are not 80 and 90 N/mm. They are approximately as listed above. Great for the street but a little soft for the track. The Ohlins will be much stiffer as mentioned at 70/80 N/mm.

 

Reviving an old post here, as it seems relevant. I am currently debating options for my 981S PASM/PDK car. I do not have the capability to go with any set of PASM compatible coils in the near future. I've thought about removing PASM and going with a set that is not compatible, however that is a last resort. Current considerations are X73, H&R HAS, and KW HAS. I actually have the KW's but have yet to install.

To the point...what are your thoughts on spring rates of 41.5 n/mm (237lb/in) and 56.9 n/mm (325 lb/in)? I am used to springs using KG, so this is a bit new to me. The conversions are not adding up. On my last 4500 lb behemoth, I was running 10k and 12k, and the car performed very well in the Great Smokey's. The purpose for the spring change is very spirited runs through mountain roads. I have swapped to X73 sways, however I may trade those out for adjustable. The large swing in transition of weight from side to side in very short intervals is not enjoyable with the stock setup. I'd love to hear thoughts and suggestions.

TIA

 

I think spring rates of 237 / 325 would be good for track and not too stiff for the street; I say that because the Bilstein damptronic (PASM) setup I have installed has 286 / 357 springs and they are great on track and bearable on the street (a little stiff but manageable). If you have PASM, you might consider the Damptronic Bilstein option...

 

I will certainly look into these, thanks for the suggestion. Are you running the DSC controller in tandem? Appreciate the info.

 

I am running the DSC, it helps a lot! I also added lower control arms and tie rod / toe arms so I can lower the ride height, add camber, and easily adjust toe. I run 2.75 front camber with 0 toe and 2.5 rear camber with 1.5 min toe in. Car handles great!

 

Thanks for that! DSC will be out of the picture if I go with the Bilstein's, but doable if I retain the KW. Control arms will be next year. Gotta make it through Christmas lol.