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Performance Suspension Lowering your Porsche 911 Carrera
 
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Pelican Technical Article:

Performance Suspension Lowering your Porsche 911 Carrera

Time:

25 hours25 hrs

Tab:

$3500

Talent:

****

Tools:

Bilstein height adjustment tool

Applicable Models:

 
Porsche 996 Carrera models (1999-05)
Porsche 996 Turbo, GT2, GT3 (2001-05)
Porsche 997 Carrera models (2005-08)
Porsche 997 Turbo, GT2, GT3 (2007-08)

Parts Required:

PSS10 Performance suspension kit

Hot Tip:

The PSS10 kit is a good value if you want a sporty suspension and lower ride height

Performance Gain:

Stiffer suspension, firmer ride

Complementary Modification:

Replace suspension bushings

Shocks & Springs: The PSS10 performance suspension kit from Bilstein is the one of the top performing kits available for the Carrera. The system includes two front coil-over spring/shock setups, and two rear coil-over 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 almost all Carreras. The PSS10 kit incorporates adjustable spring perches for both front and rear height adjustment. Installation of the kit is no more difficult than installing stock shock absorbers and new springs (see Pelican Technical Article: Replacing Porsche 911 Carrera Shocks and Springs). Also recently made available for the 911 Carrera is the Bilstein Damptronic kit, which has electronically controlled dampening settings.

After you have installed the PSS10 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 911 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 our project car, I chose to use upgraded sway bars, drop links, and strut mounts manufactured by Tarett Engineering. The sway bars are lightweight, hollow, and 26.8mm in diameter, and they 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 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 911 Carrera, 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 degree of extra negative camber.

Shown here is one-half of the Bilstein PSS 10 kit Front upper spring Rear upper spring
Figure 1

Shown here is one-half of the Bilstein PSS 10 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 PSS10 shock.
Figure 2

Shown here is a close-up of the front PSS10 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 10 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.
Figure 3

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 are aftermarket front and rear sway bar kits from Tarett Engineering.
Figure 4

Shown here are aftermarket front and rear sway bar kits from Tarett Engineering. This performance kit is specifically designed to work with the 911 Carrera 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.
Figure 5

This photo is quite possibly my favorite in this entire book. With one shot, it shows the PSS10 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 Upgrade for the Porsche 911 Carrera). 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 PSS10 kit.
Figure 6

This photo shows the Tarett Engineering front upper strut mount attached to the PSS10 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 set up very similarly to the front ones, except for the top shock mount, which is attached against an angled upper aluminum plate.
Figure 7

The rear shocks are set up 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.

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Comments and Suggestions:
hasi996 Comments: do you have anything article/pictures on installation of street performance coil overs on 2002 porsche 996 C4 cabrio
April 2, 2016
  Followup from the Pelican Staff: if this article isn't correct, http://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/60-SUSPEN-Performance_Suspension_Lowering_your_Carrera/60-SUSPEN-Performance_Suspension_Lowering_your_Carrera.htm

Then not currently.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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