PSS9 and PSS10 - spring rates & valving figures from Bilstein
 

I found a lot of misinformation on these coilvers, so after numerous calls to Bilstein, I finally got the correct figures from them for all the 996 AWD PSSx coilovers. Here they are:

PART NUMBERS:
PSS9:
C2 - F4-GM5-8846-H0
C4/(C4S) - F4-GM5-8848-H0
Turbo/(GT2) - F4-GM5-8877-H0
(Some builds will be H1)
PSS10:
Turbo/(GT2) - F4-GM5-D536-H0

SPRING RATES:
8848/8877/D536:
f: 260 lbs/in main, 145 lbs/in tender -- r :515 lbs/in main, 145 lbs/in tender
Initial combined rates w/o static sag:
f: 93 lbs/in -- r: 113 lbs/in
Final rates before main coils close:
f: 260 lbs/in -- r: 515 lbs/in

VALVING: (max force)
8848 (PSS9):
9 = soft/adjuster open, 1 == hard/adjuster closed
Rebound (in N):
f: 9=1465, 1=2050 -- r: 9=2150, 1=2820
Compression (in N):
f: 9=935, 1/1=1410 -- r: 9=1310, 1=1530

-- Max Spring Rates supported w/o revalving:
f: 350 lbs/in main -- r: 650 lbs/in main (6.3kg/mm -- 11.6kg/mm)

8877 (PSS9):
9 = soft/adjuster open, 1 == hard/adjuster closed
Rebound (in N):
f: 9=1700, 1=2775 -- r: 9=2270, 1=3060
Compression (in N):
f: 9=1050, 1=1695 -- r: 9=1420, 1=1800

-- Max Spring Rates supported w/o revalving:
f: 375 lbs/in main -- r: 700 lbs/in main (6.7kg/mm -- 12.5kg/mm)

D536 (PSS10):
1 = soft/adjuster open, 10 == hard/adjuster closed
Rebound (in N):
f: 1=1700, 10=2775 -- r: 1=2270, 10=3060
Compression (in N):
f: 1=1050, 10=1695 -- r: 1=1420, 10=1800

-- Max Spring Rates supported w/o revalving:
f: 375 lbs/in main -- r: 700 lbs/in main (6.7kg/mm -- 12.5kg/mm)

Bilstein will revalve each strut for $125.

It would be interesting to compare valving data and spring rates for other shock models too, if anyone has that data.

Instructions:
gm5-8848_C4 Manual
gm5-8877_Turbo Manual

Images:
1) (left) front turbo, (right) front C4
2) (left) rear turbo, (right) rear C4

I would just add that: pss10 the higher the adjustment number the "harder"
pss9 the higher the adjustment number the "softer"

Thanks, I updated the post to try and make that clearer, and added new spring rate data, from Bilstein, that's valving specific.

Thanks for getting the info but weren't all H0 kits replaced with H1 kits that had improved valving?

itacud, is there any possible way that i can obtain similar information for 997?

Curious: What are the stock 996tt spring rates?

That's funny. When I called Bilstein some months ago trying to get stiffer springs, they told me there weren't any. So I bought a set of Motons instead of trying to upgrade my PSS9's. Re-springing and re-valving the Bilsteins will be more cost effective for those who choose to do it.

Larry, the PSS's on my dd use standard sized springs. They can be had in any rate/length from many sources. I didn't know you could revalve the pss9s though.

FWIW, I have the PSS9 FVD version. It has stiffer and shorter springs...I know they also make a Euro version...

I wish they would have told me this. I could have saved some money doing this.

Oh larry I'm your huckleberry... We can just swap, really, no problemo... you know how well my car handles with the lowly PSS9 custom valve jobbers... hilarious

Mike

Thanks for this info!

Adding detail from inside the instruction manual that is not easily found by Googling:

996TT PSS9 Instructions note part numbers of individual items (which is what you'll see when you look at your parts and try to figure out if it's right or not):

Front:
E4-FD1-Y623A00 - Main Spring
E4-FD1-Z349A00 - Helper Spring
VM3-A012 - Shock Absorber (The full p/n on my rear shock says: F4-VM3-A012-H0 )

Rear:
E4-FD1-Y518A00 - Main Spring
E4-FD1-Y504A01 - Helper Spring
BM5-A013 - Shock Absorber (The full p/n on my rear shock says: F4-BM5-A013-H0 )

So it doesn't look like there is any difference between the off the shelf PSS9 Ann PSS10 except that you have 9 vs. 10 clicks of adjustment. The rates and valving are exactly identical. Whats weird is that the instructions specify slightly different ride heights for the 9s vs. the 10s.

As far set up with other systems, I have single adjustable Motons and I am running 550 front and 750 rear. From Moton. Set up works great.

Thanks this is great info.

Excellent post and very interesting data - thanks for the effort.

FWIW, spring rates for 997.1 Turbo's Bilstein B16 Damptronic are 336 front, 560 rear. I am currently running mine at 448 front/ 560 rear, using 70mm ID, 6 inch springs from http://www.swiftsprings.net/file/metric.pdf , and I absolutely love it. The stiffer front spring rates help a lot with making steering firmer and more precise, with no significant increase in understeer. In the 997 Turbo, stock steering is too soft/mushy (over assisted) so this change is very welcome.

Vary good info.

Thanks for into. My c4 came with PSS9 and I wonder what the rates are compared to stock.

Stock spring rates are something like 180 front and 340 rear
ROW 200f & 400r
PSS10/9 260f & 515r

Guesstimate from Pwrdhound.
http://rennlist.com/forums/996-turbo...l-overs-4.html
"ROW is generally a bit lower and stiffer than the Stock suspension. My guess is 10-15% stiffer. Stock spring rates are something like 180 front and 340 rear which would make ROW 200/400, give or take. The H&R street coil over kit is 260 front (linear) and around 500 rear (progressive). There is really no way to quote an exact number for a progressive spring. Race springs will be linear by the way.. Cheers... "

A bit of trial and error.
 

Just installed Swift Springs on 07 Porsche Turbo over Bilstein B16 with
Damptronics. Springs rates of 560F and 770R.

A little about the car:
*Original sways front and rear.
*Ride height 136R / 118 F
*Original wheels
*Pirelli P-Zero tires -PSI 34F / 38R
*Rennline solid motor mounts.

A little about road conditions: Testing was performed in typical Ventura county freeways and roads which I would rate as better than average California roads. If testing was executed on Los Angeles roads, the outcome would be much harsher, unbearable for driver and possible destruction of shocks.


Newly installed: Springs rates of 560F and 770R.

Impression:

The original valving of the Bilstein shocks are not capable of handling such high spring rates as the ride is extremely bouncy over bumps and freeway overpass transitions. The dampening strength of the shock is not capable of harnessing the load in which the spring creates over bumps.

On extremely smooth roads and curves, the ride feels stable and well planted, confidence inspiring.

Rear- Reduced side to side movement at rear when aggressively taking a long sweeping curve onto a freeway.

Front- No dipping at front when aggressively taking long sweeping curve onto a freeway.

Under/Over Steer - No change from original Bilstein set up.

Squatting is reduced under hard acceleration.

Nose dive is reduced under extreme braking.

Steering feels amazing although a bit heavy for daily driving.

Final thoughts- Not for everyday driving unless roads are smooth.

Great thread bumped! One of my favorite mods on my last car with pss9 coil overs was changing the springs. I mostly drive the 996 on the street but subscribed incase I get bored down the road or start driving it!
Shawn

Helpers too soft from the factory?
 

So I installed B14/B16s (PN 48-186346) and the rear helper springs are completely compressed even with the rear wheels off the ground The fronts are fine Some travel available in the helpers before going solid unlike the rears. I put 997 turbo wheels and 245/35 305/30 Hankooks on and now sure why the helper on rear is fully compressed Any help appreciated
https://cimg3.ibsrv.net/gimg/www.6sp...00c3eb5be1.jpg