Pelican Technical Article: Performance Suspension / Lowering / PSS10 Installation Wayne R. Dempsey
Time: 25 hours
Bilstein height adjustment tool
986 Boxster (1997-04) 987 Boxster (2005-08)
PSS or PSS 9 Performance suspension kit
The PSS kit is a good value if you want a sporty suspension and a lower ride height
Stiffer suspension, firmer ride
Replace suspension bushings
This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
Shocks & Springs - The PSS performance suspension kit from Bilstein is the one of the top performing kits available for the Boxster. The system includes two front coilover spring/shock setups, and two rear coilover spring/shock assemblies. Both the front and rear springs are easily adjustable for tweaking the exact ride height that you're looking for. The kit is a bolt-in replacement available for all Boxsters and comes in two varieties. The PSS kit incorporates adjustable spring perches for both front and rear height adjustment. The PSS 9 kit is identical to the PSS kit, with the added feature of four easily adjustable spring-rate shock absorbers. Installation of the kit is no more difficult than installing stock shock absorbers and new springs (see Pelican Technical Article: Replacing Shocks & Springs). At the time of this writing, Bilstein is gradually replacing the PSS 9 kits with the more advanced PSS 10 kits. Although they are not available yet for the Boxster, the features and performance of the PSS 10 kit will be similar to the PSS 9 kit. Also just recently made available for the Boxster is the Bilstein Damptronic kit, which has electronically controlled dampening settings.
After you have installed the PSS kit, you need to have the car realigned. Due to the design of the front suspension, the alignment specs will change when you lower the car from the stock height. See Project 58 for more details. In addition, lowering your Boxster can cause issues with clearance of wider wheels and tires. Before you test the suspension to the max, make sure you're your tire and wheel clearances are okay.
Sway Bars: For the Boxster project car, I chose to use upgraded sway bars, drop links and strut mounts manufactured by Tarett Engineering. The sway bars are light weight hollow 26.8mm in diameter and weigh about one half the weight of the stock solid bar with equivalent stiffness. These sway bars are also fully adjustable with multiple mounting holes located on each end so that you can increase or decrease stiffness by moving the drop links in or out.
Many times owners will want to upgrade their sway bars to larger units with more torsional stiffness. If you install a larger engine, or are planning on creating a dedicated track car, then adding a stiffer bar will give you a flatter ride and help with cornering. As with anything in this world though, there is a tradeoff. Stiffer sway bars may result in a rougher ride around town, particularly on bumpy pavement. Installing too stiff a sway bar may actually decrease performance if one of your front wheels begins to lift during hard cornering. It's best to speak with someone who has run a particular sized bar in their car and see how it performed for them on the street and on the track.
Adjustable Drop Links - The best way to set the drop link preload is with the car on flat ground after it's been aligned and corner balanced. After the car is balanced it will have the correct theoretical weight on each wheel so that handling will be the same going into left or right hand turns. It will also help to minimize the chances of a wheel locking up under hard braking. You want to set the drop links so that there is no sway bar preload that can will affect this balance. It may be possible to get the preload close with the car up on jack stands and the suspension hanging, but it is far more accurate to set it with the suspension loaded (car on the ground).
To remove the sway bar preload, you only need to adjust one drop link on each sway bar. With the drop links connected on both ends and the center jamb nuts loose, rotate the center link in either direction to lengthen or shorten the link. If you're rotating it the correct direction (reducing preload) it will begin to feel easier to turn. Conversely, the drop link will become more difficult to rotate if you're turning it in the wrong direction. Once you get to the point where you reach neutral preload, the drop link will be very easy to turn, and then will start to become more difficult to turn as you pass the optimum setting. Rotate the drop link back to the neutral point and lock the center jamb nuts.
With the Boxster, the front preload should be set with the wheels pointing straight - if the wheels are turned it will slightly preload the sway bar. Additionally, the rear drop link preload should be set with the front wheels facing straight - turning the wheels will tip the car slightly causing the rear sway bar to preload as well. Since the front drop link also connects to the strut, it needs to accommodate the strut turning when the wheels are turned with steering input. Therefore, the drop link rod ends need to be phased relative to each other such that they don't bind when the wheels are turned. The specially machined spacers installed on each side of the drop link rod ends are designed to roll into the rod end housing and provide an appropriate amount of clearance needed to accommodate the wheels turning lock to lock.
Even with these special spacers, proper rod end phasing is still required. To accomplish this, first adjust the preload as described previously. Lock only one jamb nut on each of the drop links. Next, rotate the wheels to full lock in one direction. Working on one side at a time, rotate the upper and lower rod ends in the same direction until they bind and will not rotate further. Then tighten the loose jamb nut. The rod ends should now be phased properly. If it's set properly there should be no binding and you should be able to rotate the entire link slightly between bind points. Next rotate the steering to opposite lock and check the opposite side to see if the link will still rotate slightly. If there is more free rotation of the link with the steering at full lock in one direction, make an adjustment to get it close to being equal for both sides. Then repeat for the other drop link.
Front Strut Mounts / Camber Plates - The camber plates are a bolt in replacement for the factory strut mounts. They eliminate the compliant factory rubber bushing and replace them with a precision Teflon-lined spherical bearing for a tighter front suspension and quicker steering response. The increased precision reduces front wheel camber changes during hard cornering which maintains the optimum tire contact patch for improved traction and better handling. Two sets of mounting holes allow for more than 1.1 deg of extra negative camber.
Shown here is one-half of the Bilstein PSS9 kit. Front upper spring Rear upper spring Front lower spring Rear lower spring Fully adjustable rear shock absorber Lock nuts for shock absorber Slip inserts for front spring retainer Spring perch support Upper / lower spring retainer Rear spring top plate Adjustment knob for front shock absorber
Shown here is a close-up of the front PSS 9 shock. The upper and lower springs are separated by the spring retainer and two blue plastic slip inserts (inset photo, upper right). The adjustment knob is located at the bottom of the shock for easy adjustment (inset, lower right). Turn the knob to 9 for a softer ride, or turn it to 1 for a stiffer performance feel. The adjustment of the ride height is accomplished by rotating the spring perch and retainer (red arrow) up or down the length of the shock.
The ride height of the suspension is adjusted by changing the location of the lower spring perches on the shock housing. Using the two special Bilstein adjustment tools, you can lower or raise the perches. Lock them together when you've achieved the proper height.
Shown here is are aftermarket front and rear sway bar kits from Tarett Engineering. This performance kit is specifically designed to work with the Boxster, and includes new bushings and drop links. The bar has multiple adjustment settings. Bolting the drop links to the outer holes produces a softer ride, whereas using the inner holes results in a stiffer suspension.
This photo is quite possibly my favorite in this entire book. With one shot, it shows the PSS9 system, the Tarett Engineering drop links, adjustable sway bars, upper camber plate strut mount, and the Brembo big brake kit (Pelican Technical Article: Big Brake Kit Upgrade). The yellow arrow shows the adjustable drop links which need to be dialed in along with the rest of your suspension components.
This photo shows the Tarett Engineering front upper strut mount attached to the PSS9 kit. The upper right inset photo shows the bottom side of the bearing assembly. The lower right inset photo shows how the strut mount moves the top of the shocks inward to achieve the maximum amount of negative camber.
The rear shocks are setup very similarly to the front ones, except for the top shock mount, which is attached against an angled upper aluminum plate. This allows the shock to mate at the correct angle to the chassis.
Comments: my 2004 2.7 boxster wheel alignment might be out could anyone tell me the proper setting
June 25, 2013
Followup from the Pelican Staff: The alignment specs vary depending on wheel size. I would grab a repair manual. It will list the specs for each one. Give our parts specialists a call: 1-888-280-7799 They will help you find what you need. - Nick at Pelican Parts
Comments: Hello, from figure 2, I am looking for 2 x large springs, 2 x plates separating the 2 springs, and 2 top plates. Could you please provide a quote? Many thanks, Joe - this is for a 2000 model year Boxster.
March 1, 2011
Followup from the Pelican Staff: These parts are not stock Boxster parts - they are only available as part of the Bilstein PSS9 suspension upgrade kit. - Wayne at Pelican Parts
Comments: In the diagram above, I am looking to purchase two sets of the letter H . Coilover retainer spring seat and locking nut.
Please provide me a quotation.
December 20, 2010
Followup from the Pelican Staff: We used to have these, but they were slow sellers, so our suppliers no longer stock these. They are indeed available still from Bilstein though - I would contact them directly. - Wayne at Pelican Parts
Check out some other sample projects from the book: