Project Porsche 987.2 Cayman S: Getting the Suspension Together! Part 2

In our last article, we got most of of the suspension for Project 987.2 Porsche Cayman in place.  Now we have to finish the job installing the parts from KW Suspension and Tarett Engineering and getting it all set up for the track!

We are using KW Suspensions HLS system on our car.  This system unlike stuff like air cups is designed so you can drive the car with the suspension extended with the suspension working perfectly normally.  The HLS was originally designed for semi-active height control on DTM race cars.  The ride height was dropped at high speeds for aero efficiency then raised in slow turns for better mechanical grip on these race cars.

We are going to be using the HLS to raise the car when it is driven on the street which will allow us to afford a lower ride height for the track.  The lower ride height will also allow our Verus Engineering Aero system to create more downforce, in particular, the splitter.  We will also be using the HLS to rake the car on the track in the turns allowing the underbody aero to work more effectively and putting more of an angle of attack on the rear wing to create more downforce.  With the HLS, we will be able to drop the rear of the car down the straights to reduce drag, like an F1 DRS.

Our plan was to mount the HLS pump where the factory battery sat and to use a superlight Lithium Iron Phosphate Antigravity ATX-30 battery on a shelf that is already in the chassis in front of the pump.  This way everything would fit under the stock plastic covers and the truck could be used to stash tools and an overnight bag for a track event.  With the light battery, the battery, HLS pump combo weighs the same as the stock battery did.

The ATX30 weighs in at an unbelievably light 5.75 lbs and delivers 880 cranking amps with 32 amp hours capacity.  It also features smart circuitry where the battery will shut off if it senses that the car is sitting for a long time.  When this happens you can push a jump start button on the battery and the car will start right up.  This is a great feature for a track car that might not run for a few weeks at a time. The ATX30 can start big V8 engines no problem and can really spin up our flat 6! We got ours from Pegasus Racing who is one of there major stocking distributors with good pricing.

Here is how the HLS cups go on the KW Clubsports.  They sit on the spring seat under the spring.  In our case, we had to get rid of the tender springs to make them fit.

The KW Suspension HLS pump was installed where the factory battery was up near the firewall.

10 comments

  1. Great as usual, curious to see how this does on the track. I run the atx-20 on my wrx. At three pounds and change it’s great. My car starts better with this over the factory battery, however it sits on a battery tender. While I haven’t had to use the restart feature, it’s another reason to like this battery.

    Have you thought about this?

    https://www.autoquestcars.com/custom-09

    1. I would be careful and run a battery tender that is for lithum batteries only! A well-known friend of ours blew up his car and almost burned down his shop because he used the wrong trickle charger!

      My opinion of this kit is that the upper links are way too short and you will have too much camber gain for rear-driven wheels. The short links can also contribute to jacking and lots of roll center and instant center migration. The short links will also cause side scrub which can contribute to instability on split mu surfaces and under certain load conditions. Lastly, the anti-squat percentage is really high and that can contribute to a loss of traction under corner exit as well as wheel hop. The Cayman/Boxter chassis has wheel hop as a known issue and they exhibit a high degree of anti.

      I may be working with a well-known Porsche suspension parts company next year to develop my own solution to these issues on the 987 chassis which if it comes to fruition will be much better than this! At least in my own opinion.

      1. Oh yeah, I use a lipo specific one. Not making that mistake. Lipo fires are for Richard Hammond anyways.

        Competition is a wonderful thing, love to see what is born!

  2. I enjoyed the 3 pages on the alignment and all of the other 987.2 Cayman content. Can you write more about setting the anti squat / dive front and rear? Also, about how the team measured the bump steer? All of the specs? Have you run the car on track yet? How did it feel, any adjustments?

    I have a 987.2 will all of the Tarett parts that your car has and have not been able to find a shop around Atlanta that will got to this level of detail.

    Thank you

    1. We are waiting for softer front springs right now. I want to go down to 10 kg and KW is backordered. The balance of the car is ok but there is a minor pitch issue I think is frequency related so I want to go softer spring wise in the front and up in the front bar. As far as bump steer, Porsche is pretty well designed and there isn’t much, but if you mess with the roll center you need to move the tie rods by close to the same about or you will get bumpsteer. Basically, if you want to measure it you take off the springs and move the car up and down and measure toe every inch and plot it. However, we did this and the toe curve on these cars is pretty good. I would talk to my local PCA or POC racers and they probably know a prep shop that can properly align and corner balance your car. The specs we gave in the article were pretty aggressive like what cup cars run so they would kill your tire on the street if your car is a daily. To make it simple to reduce anti we shimmed the front trailing arm pivot down, The 987 has a lot in the rear.

  3. Great looking build! I have a 987.2 I am setting up similarly for HPDE days.

    Any chance you can provide some insight into your recommended ride height and how you came up with it?

    I’ve got Ohlins on mine, and I have lowered it too far. My LCAs are pointed upward on the outside and thus my roll center is super low and my camber curve isn’t great. I’m trying to figure out how high to raise it but I’m a little lost.

    Thanks!

    1. We lowered the outer LCA pivot by putting a spacer on the spherical bearing. We also lowered the tie rod to reduce bump steer.

      1. Okay cool. I have that ability with my front LCAs but I am still stock in the rear. Did you aim to have your LCAs at a certain angle at ride height or at full compression?

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