Anyone here run Bilstein PSS9's?
04-22-2008, 08:30 PM
#27
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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.
04-23-2008, 03:27 AM
#28
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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.
Looking forward to your review of the PSS9's. Good luck with the install.
04-23-2008, 08:12 AM
#29
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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.
04-23-2008, 12:57 PM
#30
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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.
04-23-2008, 01:24 PM
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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.
04-23-2008, 04:10 PM
#32
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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?
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?
Last edited by Renovatio; 04-23-2008 at 04:13 PM.
04-23-2008, 04:44 PM
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04-23-2008, 06:48 PM
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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?
OP: what other suspension components are you running with the PSS9's?
04-24-2008, 06:55 PM
#37
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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.
04-25-2008, 08:52 PM
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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?
05-08-2008, 06:37 PM
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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?)
Get those Bilsteins installed already Peppy!
(By the way, what's the cost of a shock refresh from Bilstein?)
05-09-2008, 09:53 AM
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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?)
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...
05-09-2008, 01:24 PM
#44
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Those impressions were achieved on -1.1 front and -1.5 rear. Certainly my alignment played in a role in those impressions, but nonetheless balance was changing through the corner.
05-24-2008, 03:12 PM
#49
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 *** dyno data.
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 *** dyno data.