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Porsche 996 & 997 Suspension Development

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  • Porsche 996 & 997 Suspension Development

    We've been working on new Vorshlag parts development and testing suspension kits for various Porsche 911s lately. This thread will talk about developments for the 996 and 997 generations.



    The first thing we wanted to test was a Bilstein PSS10 coilover kit on this on this lowered 2002 911 Carerra C2 (above) daily driver / track toy. The installation and development work was done in February 2016.



    The owner of this car, Paul and Anna Costas, let us borrow the car for a couple of weeks to do this new product development. We also wanted to make a new Vorshlag camber-caster plate for the 996/997 2WD chassis.



    After measuring the initial ride heights, camber and toe settings on the existing setup, our crew got this 911 in the air and removed the OEM struts and H&R lowering springs from all 4 corners.



    Our engineer Jason got to work measuring the front strut towers. Then he designed an all new camber plate and spring perch to work with the OEM diameter springs.



    The PSS10 kit for this 2WD Carerra was ordered in advance and our shop manager Brad photographed it when it arrived.



    For this install we measured the H&R spring rates (they were soft - and likely similar to the OEM rates) on our digital spring tester, then did the same with the PSS10 springs, and found that the Bilstein springs were about 200% firmer. That seemed to be just right, after driving the car. Most of our competition coilover kits use 400-600% firmer spring rates.



    Jason programmed and machined the new main camber plates and spring upper perches, which work with the springs in the PSS10 kit. We also tested it with our existing 2.25", 60mm and 2.5" ID upper spring perches. We could have easily changed the included springs to a 60mm "true coilover spring", but after finding that the included PSS10 rates for this kit were adequate we left them in place.



    These are prototype versions, so the aluminum main plates were left in raw aluminum finish. The production version of these parts will be anodized red, as will the CNC machined upper spring perches.



    The images above show the prototype camber plates and two different upper spring perches that we machine - the OEM diameter for this 996 and the 2.5" coilover spring diameter. In this case the OEM front springs measured at 2.75" ID. This size crosses over with 70mm springs, which are not that common. Bilstein uses a 60mm tender spring (a very common aftermarket size) with the 2.75" ID main spring. This allows the upper part of the main spring to align with the factory upper spring perch and top mount. The change between the two sizes is in the dual spring spacer - between the tender and main spring.



    In other PSS kits we see what we call a "tapered" spring, which has the common 60mm lower diameter (they machine most of their coilover struts) and the larger OEM diameter at the top. The BMW E36 kit above is a good example of this. Luckily they didn't do that on this Porsche set.



    The camber plate install went smoothly and we were able to get a lot more adjustment for negative camber than expected. The strut tower "bubble" worked out in our favor this time and these can be used with the stock (centered) or higher positive caster (back) setting on the main plates. Camber is adjusted quickly by loosening the 3 strut top nuts and sliding he camber plate in or out relative to the strut tower.



    Out back we left the factory upper top mount in place but took measurements for a new spherical upper shock mount design. That would be a bit extreme for this car, which sees mostly daily driving and limited track use. For competition use we would suggest that, as it removes a rubber bushing from the shock load path.



    After a final 4 wheel laser alignment we test drove the car.



    I drove this 911 myself, both before and after the PSS10 installation. Surprisingly the PSS10 rode better than the original OEM shocks and H&R lowering springs. The customer loves the ride every day, and looks forward to her next track day.



    These PSS10 kits have ride height adjustment at each corner, of course. They also have a single damping adjustment on each shock. The front struts are inverted (for strength) so the knob as at the bottom. On the rear the knob is in under the rear speaker shelf. These adjustments allow the PSS10 kit to raise or lowered the car easily, for your roads and intended use. The knobs allow you to adjust the ride quality and damping firmness to suit your preferences.
    Last edited by modernbeat; 03-22-2016, 11:22 AM.
    Terry Fair - www.vorshlag.com
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev
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