718 Cayman GTS Hill Climber

[I Like Tea]

Thought I'd post about my Cayman GTS hill climber, it's the much maligned 2.5T but it's a mighty mighty thing. Here it is on the IoM TT course last weekend, well a bit of it anyway, Glen Helen - Sarahs Cottage - Cron y Voddy.



I'll post later about engine development, suspension etc, basically how I've completely ruined a perfectly good road car

[I Like Tea]

Thanks for the replies. Current issue I'm grappling with is suspension setup. I've converted it from PASM (Porsche active suspension thing) with stiffer Eibach springs to coil overs as it was too soft. I took a stab at spring rates picking a circuit rate as a starting point, 120 N/mm front and 140 N/mm rear. It's crazy stiff for the road but the times I'm doing on the hills are good, so was going to leave it alone until I noticed this anomaly from a photo taken at Loton Park that shows it lifting an inside rear wheel on corner exit, was not expecting that. Initial investigation involved sticking it on a jack and finding it only has about 20mm of droop now arranging to send it to someone who actually knows what they are doing, nothing is ever easy..... or cheap.

[I Like Tea]

conanius said:

What suspension is it you have fitted? looked excellent on that run

Nitron R3. It is well damped and until I saw the lack of rear droop I was just going to leave it as is for the season.

[I Like Tea]

motorhole said:

*Amateur opinion proviso*

You might find that the amount of droop in your setup is limited by the ARB and drop links rather than anything to do with coilovers and springs. You can test whether this is the case by measuring droop, then disconnecting the ARB and measuring again. Using adjustable drop links to change the angle of the ARB might buy you 10, maybe 20 mm extra droop. Beyond that, you would need to consider a softer ARB which might have a more adverse handling effect than just accepting the limited droop.

You make a very good point that I had not considered, thank you. Unfortunately the regulations don't allow adjustable drop links, so I'll need to be creative to find a solution, who needs a rear ARB anyway....

[I Like Tea]

Dr G said:

Do they allow drop links that used to be adjustable but have since been attacked with a mig?

Great clip above; not a lot keeping up with that!

I have thought about that and other workarounds.

[I Like Tea]

Now have some smaller lighter 18" wheels to replace the 20" GT4 wheels I was using. A little wider at the front to fit a 255 tyre. It doesn't really go over speed bumps anymore...

[I Like Tea]

CKY said:

Having just watched the video, this picture illustrates what it sounds like is happening at 0:30 in your video - a gentle corner with the revs flaring (and what sounds like TCS dialling the revs back) on corner exit. It's hard to tell without physically being in/driving the car, but it does look fairly bouncy from onboard - as others have stated this could be causing you to lift for corners or bumps that you'd otherwise be able to take at higher speed. Be interesting to see what the people you've contacted have to say about making it better for your use.

Thanks for this, made me go and check the data logs. At the point you spotted in the video accelerator position is 104% and throttle position dips to 15%, so it is the TCS closing the throttle. The consensus is the spring rates are too high and should be dialled back a bit. They also softened the rear compression a click. We’ll see what it’s like at Loton Park this weekend.

[I Like Tea]

Hol said:

Is this the Ninemeister tuned car?

GTS500….

Yes it is.

[I Like Tea]

Spent a morning at a local suspension specialist having their geo settings put on the car and having it corner weighted, didn’t have enough time to do that before the start of the season. On spring rates the consensus is it’s too stiff but not crazily so, probably needs to come down 20N/mm on each corner. Not something I’ll do this season as the car is performing brilliantly and I don’t want to fix something that isn’t broken.