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Anyone here run Bilstein PSS9's?
I've searched and searched but can't seem to find anyone running PSS9's on their RX-8. My roommate had them on his S2000 and I thought they were amazing, better than stock ride and much better handling. I was kinda wondering if people had tried them on the RX-8 and didn't like them for some reason. I noticed that the RX-8 has the cheapest price of any application I've seen. I've really been put off from doing struts/springs because of the weak sauce spring rates all of them have. Anyone have any details on the bilsteins used in the 40th anniversary? Are they just Bilstein HD's with stock springs? Any answers or input would be appreciated.
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Nobody has PSS9s as everyone is kind of scared of the quoted spring rates that Bilstein is supposedly using and think it's going to really screw up the handling balance. However, if you're curious you can try it out. I'm not sure that Bilstein would make a product that has an end result as bad as some of the people are afraid of. I'm curious about the Bilsteins, but I don't currently have enough money built up in my car fund to purchase coilovers.
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I was the one that quoted their rates a while back when I looked into them. The springs were biased to the rear being stiffer than the front. At the time, I openly questioned the logic here regarding their specs. They may in fact work very well, but I ultimately decided against them. Not to over simplify, but maybe if you were running a staggered setup these could go quite nicely - kind of like the S2K which in many years was biased with stiffer rates in the rear...
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Thanks for the info guys. I may try them out if I can't find anything else that fits my requirements. I'm really not a fan of KW coilovers and I thought I read that they make the Mazdaspeed ones. I suppose if I find I don't like the PSS9's I can just get some softer springs for the rear and have the dampers revalved.
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Actually Eibach makes the Mazdaspeed Coilovers.
https://www.rx8club.com/rx-8-racing-25/new-suspension-kit-119640/ |
So I've been thinking about the PSS9s; if the springrate really is what it is, perhaps the balance can be tweaked by running a stiffer front bar with a OE rear bar or by removing the rear bar altogether. Peppy, did you get the PSS9s or not?
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If want a hot set up get some KW Variant 3's
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Lionzoo - I haven't gotten the PSS9's yet because at this time Bilstein is reengineering their coilovers with new rates that are more in line with the stock suspension and other brands of coilovers. My dealer is getting an email once they are ready. If it takes too long for this to happen I may go with the Eibachs as I really hate KW V3's and think they are junk. I've driven an Evo, STI and S2000 with them and was completely unimpressed with the quality and performance. I had AST's on my WRX which I loved, but I'm trying to keep costs down and do very few mods to the RX-8. Basically I'm only doing wheels/suspension.
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Originally Posted by Peppy@kacework
(Post 2391643)
Lionzoo - I haven't gotten the PSS9's yet because at this time Bilstein is reengineering their coilovers with new rates that are more in line with the stock suspension and other brands of coilovers. My dealer is getting an email once they are ready. If it takes too long for this to happen I may go with the Eibachs as I really hate KW V3's and think they are junk. I've driven an Evo, STI and S2000 with them and was completely unimpressed with the quality and performance. I had AST's on my WRX which I loved, but I'm trying to keep costs down and do very few mods to the RX-8. Basically I'm only doing wheels/suspension.
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So I called up Bilstien today and got the answers I was looking for. When Red Devil got the Spring rates previously he missed a very important detail. He was correct that the rates were 370lb/in for the front and 375-445lb/in progressive for the rear. But the part he missed was the helper spring in the front also has a rate of 145lb/in, which helps in making the front stiffer than the rear. I had a feeling Bilstein wouldn't mess up like that. I'm going to pick up a set in the next couple weeks I'll let you guys know how they are.
In short PSS9 rates are 370+145lb/in helper spring front and 375-445lb/in progressive rear. The newest part number is GM5-B029-H0 |
Originally Posted by Peppy@kacework
(Post 2395320)
So I called up Bilstien today and got the answers I was looking for. When Red Devil got the Spring rates previously he missed a very important detail. He was correct that the rates were 370lb/in for the front and 375-445lb/in progressive for the rear. But the part he missed was the helper spring in the front also has a rate of 145lb/in, which helps in making the front stiffer than the rear. I had a feeling Bilstein wouldn't mess up like that. I'm going to pick up a set in the next couple weeks I'll let you guys know how they are.
In short PSS9 rates are 370+145lb/in helper spring front and 375-445lb/in progressive rear. The newest part number is GM5-B029-H0 Either way, would be great if you posted pics and let us know how it goes. |
It could be a recent change because i asked her if it was a newer part number and she said it had changed. Maybe the revision I had heard about was the addition of the helper spring. Shox.com has the new part number listed and the price is $100 more than the set they were blowing out a month ago. If I recall it had a different part number.
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I'm guessing the spokesperson just neglected to mention the tender springs. A 370 rate without tender springs would mean a very small amount of droop, though I'm kind of worried about rear droop now as it looks like the rears don't have tenders. Anyway, I'm glad you're going to try out a set, tell us how it goes!
Also, technically the springrate of springs in series is calculated with the formula 1/Keff = 1/K1+1/K2. Of course, that formula is useless for calculating coilover rates as the tender spring is designed to compress before the main spring. |
This is how according to Eibach the Calculation goes for for Tender / Main springs combinations.
To help you determine the best combination of MAIN and TENDER spring for your situation, Eibach has developed a computer program called the ERS Wizard. Every chassis / suspension / driver is unique therefore we suggest that you utilize the ERS Wizard to fully understand the dynamics of the double spring combination before you go testing. The ERS Wizard is available from Eibach on CD-ROM. Below we have listed the formulas for determining the initial and final rate as well as the transition point between the two. These are the basic formulas behind the ERS Wizard. The following formula is used to determine the initial spring rate: Ci =(CM x CT)/(CM + CT) Ci Initial Spring Rate CM Spring Rate of Main CT Spring Rate of Tender Spring The final spring rate (effective after the tender spring is closed) is simply the rate of the active Main spring. The following formula is used to determine the transition point between the initial rate and the final rate: TP =(Fc) t/(Ci) TP Translation Point Ci Initial Rate of Main/ Tender Spring Combination (Fc)t Block Load of Tender Spring - see Application List Please note: the main/progressive tender spring combination has various rates and transition points and as a result the respective formulas required to determine the rates and transition points are more complex. Please refer to the ERS Wizard for these calculations. |
As promised
Good morning! The PSS9 kit for the Mazda RX8 is GM5-B029-H0. The Front spring rate is: 370 lbs/in (main), 145 lbs/in (tender). The Rear spring rate is: Pregressive. Working range: 375-445 lbs/in. Please let me know if you have any further questions. Thank you, Rebecca Kellerman BILSTEIN Shock Absorbers Hi Rebecca, Thanks for the prompt response. It is greatly appreciated. I have a couple of more questions. 1.The stock spring rates on the RX8 are 150 lbs/in front and 113 lbs/in rear. Why is the ratio between the pss9 fronts and rears so different from stock? 2.What is the free lengths of the springs and the inside diameter of the springs? 3.Would it be possible to use a system such as ERS Eibach Springs or something similar that will enable the end user greater flexibility in suspension set-up? 4.If so what is the range of spring rates that the PSS9 struts effectively control without having to be revalved? I realize you may not be able to answer all the questions, but this would really help to make my purchase decision. Thanks again for your time. Hope this helps: 1) The motion ratios have been altered and resultant springs rates changed to optimize vehicular handling and balance. 2) Front: Main= 70mm i.d., 200mm free length, tender= 70mm i.d, 60mm free length Rear: 97.5mm upper(o.e) i.d. & 60mm lower, 252mm free length. 3) Eibach ERS springs can be used for the front application. 4) Front: ~340-400lbs, Rear: ~350-500lbs. Thank you, Rebecca Kellerman BILSTEIN Shock Absorbers |
i'm still thinking about the comment they changed the motion ratio.... :squint:
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Motion ratio as in lever arm ratio for the A-arms or as in front and rear frequency ratio? How would you even change the lever arm ratio with just a coilover set?
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Tell you guys what. I'll take pics of my entire install and the coilovers. Then I'll post my impressions, which you can take with a grain of salt. Worst case for me I can try swapping out the front springs with 400lb Eibachs and throw a big ol front sway bar on the front. I'm a big believer in Bilstein and I'm sure they put some R&D into this setup. I'll prolly have them installed by the end of the month, gotta have em on before I put my wheels on.
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Originally Posted by Peppy@kacework
(Post 2398074)
Tell you guys what. I'll take pics of my entire install and the coilovers. Then I'll post my impressions, which you can take with a grain of salt. Worst case for me I can try swapping out the front springs with 400lb Eibachs and throw a big ol front sway bar on the front. I'm a big believer in Bilstein and I'm sure they put some R&D into this setup. I'll prolly have them installed by the end of the month, gotta have em on before I put my wheels on.
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I'm sure the product won't be a disappointment. Blistien is a very good company. And the fact that they are providing this detailed information is a sign of that. I have contacted sereval companies and not all of them were that forth coming .
Just because I or anyone else on this board does not understand what they are doing doesn't mean much. So I am waiting for you driving impressions. Btw do you plan on tracking your 8. |
Originally Posted by ThecdnRX8
(Post 2398232)
Btw do you plan on tracking your 8.
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Just to keep you guys updated. I ordered the PSS9's and they will be here next Tuesday. I'll take pics of them. Hopefully I'll have time to install them that weekend.
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Just got them delivered today. Now I just have to find the time to install them. Here's some pics:
http://img.photobucket.com/albums/v2.../Bilstein1.jpg http://img.photobucket.com/albums/v2.../Bilstein2.jpg http://img.photobucket.com/albums/v2.../Bilstein4.jpg http://img.photobucket.com/albums/v2.../Bilstein5.jpg |
Looks nice. How long before you can get them installed and tested?
Also, how much do they weigh? |
Finally someone with PSS9's. They look very nice. Keep them updates coming.
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The shock bodies look a bit longer than other coilovers...
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All 4 together weigh about 50lbs. I'm not sure on separate weights as I don't have a scale. The fronts are def. pretty light. Quality is pretty good too. Adjusters have a nice snick to them. I was hoping to install them on this Sunday but I'll prolly have to wait till the next weekend.
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About that helper spring: it's mainly designed prevent coil disengagement from the perches whenever your suspension reaches full droop. The most likely scenario is that the low-rate helper spring will be completely compressed (in full coil bind) once the car's weight is on the suspension, making the helper's effective rate infinity. This means it can be treated as a solid, and the only rate in effect is the rate of the main spring. If the helper were not completely compressed, the effective total rate would actually be less than the rate of the main spring or the helper spring alone, therefore less than 145 lb/in., not the sum of the two.
Looking forward to your review of the PSS9's. Good luck with the install. |
According to Bilstein it's not a helper spring but a tender spring so it should not be fully compressed at static ride height. When one plugs in the numbers in Eibach's formula the initial spring rate is 104. That's why I am really interested to see how they work out for Peppy. He can also confirm if it is a true tender or helper.
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I thought helper spring and tender spring were interchangeable terms. Regardless, it certainly looks wimpy enough that it'll be fully compressed at static ride height.
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They are actually tender springs as referenced in the mostly German manual, lol. I had helper springs on my AST coilovers for my WRX and I could easily compress those with my hand and barely any effort. They were fully compressed when installed. The Bilsteins are def. much harder to compress.
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They are definitely tender springs, and not helper springs. Helper springs usually have a very low rate and will be compressed fully when at ride height. They are there just to keep the main spring in place when at full droop (i.e. when you raise the car on jack stands). The tender springs are similar, but they usually have a much higher rate (around the 150lbs/in quoted by Bilstein).
But the thing is because these tender springs have a much lower rate than the main spring, they will be mostly and preferentially compressed at ride height. Because of the discrepancy in spring rates, most of the travel will happen in the tender spring first: in a turn they will become fully compressed (making K = infinity), and then the effective K is the rate of the main spring. This is done to give a progressive feel to the spring for a softer ride on straights, but you can see that as soon as you start turning, you are relying solely on the main spring. Personally, I'm very interested in your opinion of this suspension setup, as Bilstein PSS9 seems to be the first and only coilover with a stiffer rate in the rear (as I would also prefer). Are they expecting a staggered tire setup to be used? |
Originally Posted by Renovatio
(Post 2423988)
Are they expecting a staggered tire setup to be used?
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If the rates are that high in the rear I think a front sway bar would be a very good option in terms of performance to bring the balance back to stock levels.
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I'm thinking of running without a rear sway. Then again Speedsource uses 800 lb/in all around and they seem to be okay.
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If I were getting the PSS9's, I would probably keep the stock rear sway bar, but upgrade to an adjustable front sway bar, with adjustable endlinks front and rear. That way I could tune out any under/over-steer using the front sway, without losing too much rear independence.
OP: what other suspension components are you running with the PSS9's? |
Renovatio - I've only had the car for a couple months, but I got the feel for the stock suspension. I'm going to start with the coilovers then go from there. I'll add a sway bar and endlinks if I feel it needs it. I rather add parts one at a time and see the indivual results.
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Originally Posted by Peppy@kacework
(Post 2426292)
Renovatio - I've only had the car for a couple months, but I got the feel for the stock suspension. I'm going to start with the coilovers then go from there. I'll add a sway bar and endlinks if I feel it needs it. I rather add parts one at a time and see the indivual results.
What are your thoughts on these coilovers? What tire sizes are you running? |
Are these on the car yet?
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Sorry guys, been crazy busy with work and other things. Hopefully I'll get a chance to install them next weekend.
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A couple more thoughts on the weird spring rate. On the stock RX-8, it feels like it initially understeers in a corner, but will transition to oversteer as the gs ramp up. It feels like the stock rears are getting into the bumpstops earlier than the fronts and as a consequence the rear steps out first despite the spring rates being a bit more biased towards understeer.
Get those Bilsteins installed already Peppy! (By the way, what's the cost of a shock refresh from Bilstein?) |
So what is the average price for this set-up? How do they compare to the Tokiko D-Spec and Mazdaspeed?
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Originally Posted by LionZoo
(Post 2452446)
A couple more thoughts on the weird spring rate. On the stock RX-8, it feels like it initially understeers in a corner, but will transition to oversteer as the gs ramp up. It feels like the stock rears are getting into the bumpstops earlier than the fronts and as a consequence the rear steps out first despite the spring rates being a bit more biased towards understeer.
Get those Bilsteins installed already Peppy! (By the way, what's the cost of a shock refresh from Bilstein?) 0.0 camber front -1.5 camber rear A lot of room to play with on our factory suspension for different aligment settings... |
Originally Posted by Red Devil
(Post 2453477)
Keep in mind, factory alignment specs are basically:
0.0 camber front -1.5 camber rear A lot of room to play with on our factory suspension for different aligment settings... |
I'm aiming for next weekend on the install.
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what is the max drop?
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installed yet?
also, how come the pss9 is not searchable through the rx8 anymore? |
Sorry I've been slacking. Sunday is the day though. I had to order up some spanner wrenches since they didn't come with it.
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Someone mentioned they look longer and that will largely be due to the fact that it's not independent ride and spring preload adjustable. This is why they have the Tender springs in there.
One of the reasons this suspension will be more affordable than others is because you will need to retrofit some of the rear suspension uppermounts to these coilovers. Keep us updated, i'm super interested in how you like these. i think the 8 does better with longer stroke suspensions for some reason. i haven't looked into it too deep just my ass dyno data. |
You can use a flathead screwdriver in place of the spanners.
JUST TAP IT IN......... das how we do it if people lose theirs. Rishie |
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