| Suspension
improvements should be among the first items on your agenda for upgrading your 911.
Besides Driver Training, these are the most important and cost effective changes to your
Porsche that will make your car faster and more controllable.
An
autocrossing 911 in need of suspension work

Here is a street-driven 911 with a properly prepared
suspension on slicks exiting (old) Turn nine at Portland International Raceway
Rennsport Systems
offers many choices when upgrading your suspension components for racing,
autocrossing, or everyday driving. We can help you choose the proper components that will
transform your 911/930's handling and make the car a lot more fun and much easier to
drive.
Changing Shock Absorbers, Swaybars, Torsion Bars or
Springs, Chassis Stiffeners, replacing rubber bushings with Poly-Bronze® are all
components that can be improved individually or as a complete system. Many upgrades will
have a negligible effect on ride quality.
Tires and wheels play the largest role in how your car
handles. Fact is, tires are the single most important performance component on your car.
The traction that they provide allows the springs, shocks, and swaybars to help generate
higher cornering forces and the ability for the braking system to slow the car down.
Some of the adjustments listed below can affect the car's
handling and cornering capabilities; others will affect the transitions from
acceleration-to-braking and corner entry and exit. Aerodynamics play a larger role at
higher speeds.
When fine tuning your Porsche, make One Change at a
Time. This will allow you to evaluate these effects and will enhance your
understanding of how your car handles.
Here are some well proven suspension packages for varying year 911's:
| Year |
Shocks |
T-bars/Springs |
Swaybars |
| Street '66-'68 |
Bilstein HD |
21mm/26mm |
20mm F&R |
| Street/Track '66-'68 |
Bilstein HD/Sport |
22mm/27mm |
20mm F&R |
| Street '69-'73 |
Bilstein HD |
21mm/26mm |
20mm F&R |
| Street/Track '69-'73 |
Bilstein HD/Sport |
22mm/27mm or 22mm/28mm |
20mm F&R |
| Track '69-'73 |
Bilstein Sport or RSR |
22mm/28mm or 22mm/29mm |
20mm or 23mm F&R |
| Street '74-'77 |
Bilstein HD |
21mm/26mm |
20mm F&R |
| Street/Track '74-'77 |
Bilstein HD/Sport |
22mm/27mm |
20mm or 23mm F&R |
| Track '74-'77 |
Bilstein HD/Sport |
22mm/27mm |
20mm or 23mm F&R |
| Street '78-'89 |
Bilstein HD |
22mm/28mm |
20mm or 23mm F&R |
| Street/Track '78-'89 |
Bilstein HD/Sport |
22mm/28mm or 22mm/29mm |
23mm F&R |
| 930 Street |
Bilstein HD/Sport |
22mm/29mm |
23mm F&R |
| 930 Track |
Bilstein RSR |
22mm/31mm or 22//33mm |
23mm/25mm |
| 964 C2/C4 |
Bilstein HD |
H&R Sport |
RS adjustable 23mm/18mm |
| 964 RSA |
Bilstein HD |
H&R Sport |
RS adjustable 23mm/18mm |
| 964 Track |
Moton Clubsport |
Custom main/tender package |
RS adjustable 23mm/20mm |
| 993 & TT Street |
Bilstein HD |
H&R Sport |
RS adjustable 23mm/20mm |
| 993 & TT Street/Track |
PSS-9 |
PSS-9 |
RS adjustable 23mm/20mm |
| 993 & TT Track |
Moton Clubsport |
Custom main/tender package |
RSR adjustable 23mm/22mm |
| 996 |
Bilstein HD |
H&R Sport |
GT-3 |
| 996 TT Street/Track |
PSS-9 |
PSS-9 |
GT-3 |
| GT-3 Street/Track |
Moton Clubsport |
Custom main/tender package |
GT-3 (stock) |
Chassis Tuning &
Modifications
Tires
| Modification |
To Reduce Understeer or Increase Oversteer |
To Reduce Oversteer or Increase Understeer |
| Front Pressure |
Increase in 2.5 lb increments |
Decrease in 2.5 lb increments |
| Rear Pressure |
Decrease in 2.5 lb increments |
Increase in 2.5 lb increments |
| Front Tire Width |
Increase Width |
Decrease width |
| Rear Tire Width |
Decrease Width |
Increase Width |
| Front Aspect Ratio |
Higher Ratio |
Lower Ratio |
| Rear Aspect Ratio |
Lower Ratio |
Higher ratio |
| Front Tread Depth |
Decrease Depth |
Increase Depth |
| Rear Tread Depth |
Increase Depth |
Decrease Depth |
Wheels
| Front wheel width |
Wider |
Narrower |
| Rear Wheel width |
Narrower |
Wider |
| Front wheel weight |
Lighter |
Heavier |
| Rear Wheel Weight |
Heavier |
Lighter |
Alignment
| Front Camber |
More Negative |
More Positive |
| Front Caster |
More Positive |
More Negative |
| Front Toe |
More Toe-out |
More Toe-in |
| Rear Camber |
More Positive |
More Negative |
| Rear Toe |
More Toe-out |
More Toe-in |
Swaybars
| Front |
Soften |
Stiffen |
| Rear |
Stiffen |
Soften |
Spring or Torsion Bar Rates
| Front |
Soften or Smaller |
Stiffen or Bigger |
| Rear |
Stiffen or Bigger |
Soften or Smaller |
Shocks
| Front |
Soften |
Stiffen |
| Rear |
Stiffen |
Soften |
Suspension Bushings
| Front |
Stiffen |
Soften |
| Rear |
Soften |
Stiffen |
Brake Proportioning
| Front |
Reduce Pressure |
Increase Pressure |
| Rear |
Increase Pressure |
Reduce Pressure |
Weight Distribution
| Front |
Reduce |
Increase |
| Rear |
Increase |
Reduce |
Aerodynamics
| Front |
Increase Downforce |
Decrease Downforce |
| Rear |
Decrease Downforce |
Increase Downforce |
We also have the superb ERP Racing Suspension Systems and Products.
These are the very best no-compromise suspension parts
available for the 911/930/964/993/996-series cars.
Call or e-mail us us for an individual consultation and
recommendations for street or track suspension systems.
E-mail to: info@rennsportsystems.com
or call 503.244.0990
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