Steve Dallas

Since posting about my Ohlins suspension, I have received numerous PMs and emails asking me for more detailed thoughts about the PSS9s I ran for road and track previously. I think it prudent to add this quick post summarizing my thoughts about the PSS9.

I have driven on PSS9s on the track and street for the better part of 3 years, so I am very familiar with them. Let me take a moment to explain how the adjuster works on the PSS9. Have a look at this scale:

1..........2345678..........9

A setting of 1 is full hard. It is so hard, it will rattle your teeth out of your head as you skip off the track, which makes it useless. A setting of 9 is full soft. It is so soft, it is like driving a '59 Cadillac. Unless you like bouncy-floaty, it is also useless. That leaves the settings bunched in the middle. There really isn't much difference between a setting of 2 and 8, as the adjuster only turns 180 degrees, and most of that travel is between 1 - 2 and 8 - 9. At first, you will play around in that area trying to find what you like best. Eventually, you will realize that 5 is best for most conditions, and you will set it there and forget it (or wish you had your $500 back).

In my testing, I found a setting of 5 front and rear to provide a sporty feel on the street without being harsh or showing signs of weirdness that some of the other settings induce. On the track, I found a setting of 5 front and rear to be the best at keeping the car planted in most situations. Settings lower than 5 exhibited problems with compression over bumps and curbs, and higher settings exhibited problems with rebound, such as wheel hop under braking. Changing settings was rarely predictable and proved frustrating on many occasions. After experimenting with different settings over about 6 track days, I decided to just leave them on 5 all around, treat them as non-adjustable, and just drive to the available grip levels.

There is also the issue of what the adjuster is actually adjusting. I call it a "comfort" control, because it is not actually adjusting full spectrum rebound. It adjusts some combination of compression and high frequency rebound, and those are not always compatible in each setting. Some settings are just plain weird. High frequency rebound speaks to comfort, but low frequency rebound speaks to performance, and LF does not seem to change--except at the extremes of adjustment (and not in good ways).

The PSS10 has a much better design, but it is not available for our cars, unfortunately.

If I were buying Bilstein again, I would buy the non-adjustable PSS and save the $500 and months of frustration. Really, PSS9s set on 5 are very good street coilovers, and are also quite competent on the track. The non-adjustable PSS version should yield similar performance at a lower cost and with less frustration. I have not run the PSS myself, but I have spoken to the tech folks at Bilstein, and they tell me that, even though the spring rates are slightly different (370/240 PSS vs 340/240 PSS9), they are valved to those rates as if a PSS9 set on 5.

One last thought. Both PSS9 and PSS coilovers maintain a bump frequency that will bias a typical RX-8 from slight understeer toward slight oversteer with the factory sway bar ratio.

Evolv

iTrader: (1)

Hey Steve

I'm in the process of selecting coilovers for my Anniversary RX8 and wanted to know your thoughts on the comparison between the Ohlin R&T and the Bilstein PSS/PSS9.

What I would like to achieve is an okay drive-able car but something that can really dominate in Autocross STX. For my driving style I need something that is more neutral or understeer bias. I prefer a little push into the corners as opposed to oversteer coming out. The reason mostly being is I compete locallly on an abandoned runway that is only 75' wide and 2000' long, which leads to a lot of cross over and slalom segments.

I noticed in some of your posts that you have had nothing but grief with the Ohlin's and underwent a long process setting them up.

Would there be more or less grief with say PSS9? I know that going to PSS eliminates the selection, which leads me to believe that sway bars and tire pressure is all that I would need to adjust.

For me the Ohlins would cost $1000 more than the PSS and $300 more that the PSS9s. What are your thoughts?

Steve Dallas

I would love to help you out, but I literally know nothing about autoX. I am a road course guy, and setups between that and autoX can be quite different. If a tendency to oversteer is amplified in autoX, I would probably want to steer you away from Ohlins, unless you spring for Goodwin's race version.

Evolv

iTrader: (1)

I don't want to spend the money for the Race version so I might just get the Bilstein PSS coil-overs. Sounds like the best solution.

Steve Dallas

For autoX, the PSS9 might actually be the better solution. On a short, tight course, the adjustability might be useful and create an advantage. There is at least 1 long thread here about PSS9s as used in autoX with success.

https://www.rx8club.com/series-i-whe...140733/page15/

Evolv

iTrader: (1)

Thanks, I haven't ordered anything yet but will soon.

Figs

I thought I was somewhat competent when it comes to coilovers but I can't quite figure these out. Is there a way to adjust the ride height on these or are they just drop in and go. I couldn't seem to figure how since the entire body of it spins aside from the spring preload

Steve Dallas

The shock body does not spin. You simply use the adjusters to change the preload on the springs, which also changes the ride height.

Figs

Is there a range of how far you can go without putting an excess of preload?

Steve Dallas

Yes. You can download the instructions from Bilstein's web site to find out more.

Evolv

iTrader: (1)

I think the range is 25mm front and 15mm rear

blu3dragon

iTrader: (1)

I think this means stiffer springs than what comes with PSS or Ohlins R&T.

For the money, I would go PSS, swap out the springs and get a revalve.
Since you can customize spring rates and valving, you don't really need adjustable shocks.

Of course, the springs that come with PSS (or Ohlins R&T) will already be a big upgrade over stock and may be plenty for you locally, or at least a very good starting point until you get more experience.

Evolv

iTrader: (1)

Experience I have (we could all use more practice). I think there is some weird geometry stuff going on with my 40th Anniversary RX8 and I can't get the BC Racing Coilovers set up properly. After looking and looking I think the only Coilovers that may work on my car are the PSS.

I still have not ordered anything because there are no PSS or PSS9's available until late May (back ordered everwhere)

I'm at a point where I may just go back to Koni's and possibly some RB Springs. That or trade it all in for a 2016/17 Club Miata.

Steve Dallas

I missed the word "dominate". Yeah, definitely not going to dominate with medium springs.

There is nothing different about the suspension in the 40th Anniversary cars. Most likely, it is the BC "Racing" product that is giving you grief.