B5 RS4 Bilstein PSS9 Review
Posted: Sun Sep 09, 2007 3:31 am
I have now had PSS9s installed for about two weeks, though some of my impressions are based on a drive immediately after install so I will update again later once the springs have fully settled and I have lowered the car to the correct height.
Prior Set up
I previously installed the H&R fat antiroll bar with both front and rear bars set to maximum stiffness, did not affect ride quality. The bars a lone made a significant difference, particularly at low speeds and turn in, but was still very floaty at high speeds and unsettled in corners and undulations.
I was concerned that the ride quality with the PSS9s would become significantly harsher but I don't notice any great difference in the compliance between the PSS9s and the standard. Roads are also very bumpy over here with pot holes, old concrete slab types and old bitumen.
My original suspension had done approx. 20 000 miles so was still much like new.
Spring height and firmness
The PSS9 progressive rate springs are certainly firmer. I am no fatty but pushing down on the fenders there is little give whereas before there was considerably more.
The mechanic set the ride height to maximum until the springs settle and it was about 1 cm higher on install.
After two weeks it looks like it is probably sitting a tad higher though the measurements now seem very close to stock @ ~ 66 cm rear & 65 cm front. Ride quality still feels the same.
I will probably lower the car by about 2-3 cm when I get around to it and on spirited drives maybe more, but I look forward to the experimentation.
Damper Settings
The Bilstein monotube dampers are gas pressurized types with 9 combined compression and rebound settings. The manual states 1 is firm and 9 is soft.
I had them set to 4 which is about mid way.
Turning the front wheels on full lock the adjuster knob is easily accessible and visible. For the back wheels you have to lie down and reach under the back of the car over the rear wish bone. The dial is then easily accessible by hand but not visible. Car ramps would probably be handy for this part.
Compared to the KW V3s I have heard that the Bilsteins are more responsive but as a result can be a little skittish and provide less give in the first few mm. I believe the extra responsiveness is due to the high gas pressurized system, valving and piston size in the Bilsteins. It seems to be down to personal preference whether one wants their dampers to be more or less responsive.
The KW V3s also have independent and greater rebound and compression adjustability but the rear shocks must be removed to adjust.
I liked the idea of being able to easily adjust the Bilsteins to a firmer setting in a matter of minutes for spirited drive days.
Impressions
Immediately after install I went for a spirited drive through a number of sign posted 35 km/hr to 45 km/hr twisties on a variety of smooth to rough road surfaces. Car was a little high but handling was definitely better.
I took the Misses who is usually having kittens during drives but she also felt the car was much more stable and safer and no complaints were heard which is unusual.
Despite the springs having not settled in, body roll was noticeably improved and car feels much more balanced through turns. Turning in felt much more neutral and directed. I notice a slight roll and change of weight and then the springs appear to firm up nicely.
The car is now much better damped and no longer feels unsafe or out of control. Is much less bouncy but no real noticeable loss of ride quality.
I will probably set the dampers firmer to the number 3 setting as I still believe the car is a little under damped. Though I will lower the car first by about 1 inch to see what difference that makes.
I am yet to test the car on any high speed cornering but I expect the firmer springs and stronger damping will help.
Conclusions and comparisons
Obviously Bilsteins are a very reputable brand and they perform very well with easy adjustability. There is also no noticeable loss in ride quality/comfort and if necessary the ride height can be set as stock or slightly higher.
Competitors include KW Variant 3s and Stasis Track Sport and all are within a similar price range with KW followed by Stasis being slightly more expensive. Both the Bilsteins and KW V3s have rebound and compression adjustability, though the KWs has independent rebound and compression. The Stasis is rebound only but comes with a 90 day spring exchange program, Koni adj shocks are used with Stasis digressive valving.
Bilstein is gas pressurized and is said to be more responsive than KW.
Bilstein has a digressive piston head design and deflective valving, whereas Stasis talks about digressive valving.
KW make an RS4 specific set up where as Stasis and Bilstein use the same setup for the S4.
My main reason for gong with Bilstein over KW was the ease of damper adjustability. I would have gone with Stasis but my driving style did not justify the added expense that I was quoted.
Prior Set up
I previously installed the H&R fat antiroll bar with both front and rear bars set to maximum stiffness, did not affect ride quality. The bars a lone made a significant difference, particularly at low speeds and turn in, but was still very floaty at high speeds and unsettled in corners and undulations.
I was concerned that the ride quality with the PSS9s would become significantly harsher but I don't notice any great difference in the compliance between the PSS9s and the standard. Roads are also very bumpy over here with pot holes, old concrete slab types and old bitumen.
My original suspension had done approx. 20 000 miles so was still much like new.
Spring height and firmness
The PSS9 progressive rate springs are certainly firmer. I am no fatty but pushing down on the fenders there is little give whereas before there was considerably more.
The mechanic set the ride height to maximum until the springs settle and it was about 1 cm higher on install.
After two weeks it looks like it is probably sitting a tad higher though the measurements now seem very close to stock @ ~ 66 cm rear & 65 cm front. Ride quality still feels the same.
I will probably lower the car by about 2-3 cm when I get around to it and on spirited drives maybe more, but I look forward to the experimentation.
Damper Settings
The Bilstein monotube dampers are gas pressurized types with 9 combined compression and rebound settings. The manual states 1 is firm and 9 is soft.
I had them set to 4 which is about mid way.
Turning the front wheels on full lock the adjuster knob is easily accessible and visible. For the back wheels you have to lie down and reach under the back of the car over the rear wish bone. The dial is then easily accessible by hand but not visible. Car ramps would probably be handy for this part.
Compared to the KW V3s I have heard that the Bilsteins are more responsive but as a result can be a little skittish and provide less give in the first few mm. I believe the extra responsiveness is due to the high gas pressurized system, valving and piston size in the Bilsteins. It seems to be down to personal preference whether one wants their dampers to be more or less responsive.
The KW V3s also have independent and greater rebound and compression adjustability but the rear shocks must be removed to adjust.
I liked the idea of being able to easily adjust the Bilsteins to a firmer setting in a matter of minutes for spirited drive days.
Impressions
Immediately after install I went for a spirited drive through a number of sign posted 35 km/hr to 45 km/hr twisties on a variety of smooth to rough road surfaces. Car was a little high but handling was definitely better.
I took the Misses who is usually having kittens during drives but she also felt the car was much more stable and safer and no complaints were heard which is unusual.
Despite the springs having not settled in, body roll was noticeably improved and car feels much more balanced through turns. Turning in felt much more neutral and directed. I notice a slight roll and change of weight and then the springs appear to firm up nicely.
The car is now much better damped and no longer feels unsafe or out of control. Is much less bouncy but no real noticeable loss of ride quality.
I will probably set the dampers firmer to the number 3 setting as I still believe the car is a little under damped. Though I will lower the car first by about 1 inch to see what difference that makes.
I am yet to test the car on any high speed cornering but I expect the firmer springs and stronger damping will help.
Conclusions and comparisons
Obviously Bilsteins are a very reputable brand and they perform very well with easy adjustability. There is also no noticeable loss in ride quality/comfort and if necessary the ride height can be set as stock or slightly higher.
Competitors include KW Variant 3s and Stasis Track Sport and all are within a similar price range with KW followed by Stasis being slightly more expensive. Both the Bilsteins and KW V3s have rebound and compression adjustability, though the KWs has independent rebound and compression. The Stasis is rebound only but comes with a 90 day spring exchange program, Koni adj shocks are used with Stasis digressive valving.
Bilstein is gas pressurized and is said to be more responsive than KW.
Bilstein has a digressive piston head design and deflective valving, whereas Stasis talks about digressive valving.
KW make an RS4 specific set up where as Stasis and Bilstein use the same setup for the S4.
My main reason for gong with Bilstein over KW was the ease of damper adjustability. I would have gone with Stasis but my driving style did not justify the added expense that I was quoted.