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-   -   Custom Bilstein PSS9 Coilovers (http://www.bimmerfest.com/forums/showthread.php?t=648126)

achong 09-25-2012 02:34 PM

Custom Bilstein PSS9 Coilovers
 
Hi guys,

I just want to share about the new coilover setup for the beast and provide a description of the modification process. I bought my beast used, and the previous owner threw on Koni FSD, which were way too soft for my taste. She felt sluggish around corners, and it felt like I was either driving a boat or a SUV not a 70k super sedan. The ride would sway, dive, and bounce around even on the slightest dips. I decided to go with the Bilstein PSS9 coilover set up because Bilstein offers a revalving service at a reasonable price. The money I saved from going with the PSS9's instead of KW's V3 went into the revalving service. By doing this I was able to up the stiffness to whatever I wanted. I chose this route because of the recommendation from my mechanic at Precision Motorsports in San Luis Obispo, CA who specializes in race car preparation and he felt like the spring rate and valve stiffness from a majority of coilover kits were designed to appeal to the mass market and not necessarily to the true driving enthusiasts. We sent the shocks on over to Bilstein to up the stiffness. Stock PSS9 valve rates were (F)184/130 (open) and (F)300/175 (closed), the rear were 200/136 (open) and 312/200 (closed). The shocks were revalved to (F)321/151 (open) and (F) 1065/483 (closed), and the rear were stiffened to 335/148(open), and 868/461 (closed) (tested at 10"/sec speed). The springs that came with the kit were also replaced with H&R racing springs with a spring rate of 800lbs all around (front and rear).

Because I had the springs from the kit swapped out with shorter/smaller(diameter) springs (to save weight and increase stiffness) I needed additional hardware components in order to insure fitment. My mechanic fabricated and machined the necessary hats so that the springs could be mounted. Helper springs also had to be ordered from Bilstein to help the main spring stay in contact.

Here is a write up of how the project was performed:

Instructions to be used in conjunction with standard shock replacement instructions readily available online.

After front struts have been removed, reach up and hand remove BMW upper spring perch/ bearing assembly which will not be used in racing set - up.

https://sphotos-a.xx.fbcdn.net/hphot...83117018_n.jpg

Pre assemble your Bilstein PSS9 front struts with collar nut first [ lock nut is optional ] then helper spring, then divider collar, then main spring on top, then special hat with needle bearing [ optional for quieter steering ]

https://sphotos-b.xx.fbcdn.net/hphot...07164152_n.jpg

Now this assembly can be fitted to car just like you fit the stock set - up. For a first try at ride height set the front spring nut in the middle of Bilstein threads.

https://sphotos-b.xx.fbcdn.net/hphot...05457972_n.jpg

After rear shocks have been removed with perch attached,
use normal safety measures described by factory with spring compressors to remove spring and top hat. With a bench grinder you can grind down inner perch so that the main spring inside diameter clears the cone in the middle for a full metal to metal spring contact.

https://sphotos-a.xx.fbcdn.net/hphot...59266864_n.jpg

https://sphotos-a.xx.fbcdn.net/hphot...81526790_n.jpg

https://sphotos-b.xx.fbcdn.net/hphot...51762463_n.jpg

Now install flat washer to shock

https://sphotos-b.xx.fbcdn.net/hphot...69008039_n.jpg

Install adjuster nut [ locknut optional ] Slip helper spring on, then divider collar then main spring, then top hat and upper perch, torque center nut

https://sphotos-a.xx.fbcdn.net/hphot...43871696_n.jpg

the picture shows main spring below, either way is fine. Now install rear assembly into car, for initial ride height you can try adjusting the nut 40mm from top of the thread

https://sphotos-a.xx.fbcdn.net/hphot...84275519_n.jpg

https://sphotos-a.xx.fbcdn.net/hphot...54490609_n.jpg

Initial impressions:
The car is now extremely responsive to accelerating turning and minimal dive under braking, car is amazingly flat it corners now, much more stable in all conditions, huge increase in confidence entering curves, car feels much more planted, adjusting the shocks from mid position now will be the next step.

I'll admit I was quiet hesitant at first to go with such a stiff setup, and this type of setup may not be for everyone, but after installing it and driving around town even with the rears set to the 9 (highest stiffness) the car finally felt right...the way it was meant to be as she left had just left the factory. My beast is my daily driver, and the stiffness is not rough at all. She now handles like a new ride, and is screaming to be driven hard! Hats off to Franz at Precision Motorsport for going the extra mile to machine the necessary components and finding the right helper springs.

[Disclaimer] this is a racing modification for off road use only ! Next stop Buttonwillow Raceway Park !
Feel free to contact Franz Bluschke at Precision Motorsports if you are interested in learning more about a custom suspension setup.
racing at fbluske@hotmail.com or 805-423-5502

veli510 10-31-2012 10:03 AM

i just bought used coilovers as well. they are pss9 but for e46. i dont know if the springs are good or not but from you are describing is that, i can use H&R springs if the springs i have fail?

my coilovers are on it's way to me, from wisconsin. just barely ordered them from someone in the forum. they have about 40k on them and he told me 1 struct is leaking so for sure i have to get it repaired.

is there anything you recommend or advices . i'm pretty new with all of this :rofl:

achong 10-31-2012 10:26 AM

the racing springs i got for this setup are actually smaller in both length and diameter. hardware modifications had to be done in order to insure fitment. the hats were replaced with custom ones fabricated by my indy. If the springs are bad you should be able to get replacement one from bilstein. too bad your car isn't the same as mine, or i'd sell you the springs that came with the coilovers. If the shocks are leaking you can send them in to get the revalved.

veli510 10-31-2012 10:41 AM

Quote:

Originally Posted by achong (Post 7168236)
the racing springs i got for this setup are actually smaller in both length and diameter. hardware modifications had to be done in order to insure fitment. the hats were replaced with custom ones fabricated by my indy. If the springs are bad you should be able to get replacement one from bilstein. too bad your car isn't the same as mine, or i'd sell you the springs that came with the coilovers. If the shocks are leaking you can send them in to get the revalved.

thanks for fast reply OP. your car looks great


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