Suspension travel

hi i am deciding in getting some coilovers pss9,pss10.....but thinking about it i ask if u lose suspension travel when adjusting the hieght(lowering),thus affecting the ride quality and performance.

cool new avatar

Greetings from Stillwater, MN! Wow, nice week (last week) for driving the cars around here. I will just give you my experience based on 1 P-car. Sure others will chime in too. I went from stock C4S suspension to PSS10s. Both my wife and I noticed a much better ride quality. Perhaps my stock shocks were bad. The old suspension seemed rather "jarring" over bumps. The new one seemed much better dampened. We tested the PSS10s at settings from full soft (0) to sport (10). Even at 10 the ride was better than stock. I decided on 5 front and 7 rear. I relied on my shop for settings, just giving them directions that it was for street use. Fender height as purchased was 27"F and 26.5 rear. With the PSS10s we went to 25.5" front and rear. My experience with the lowered settings is this: No problems driving, even hitting some of the major potholes this year (worst year ever here in the metro, IMHO!). I never had the feeling that I had hit the stops on the shocks. You DO need to be really careful of the front spoiler when turning onto a steep driveway. I have a stock C4S spoiler which, luckily, is not very expensive.

i think my question would be ...is there any coilover system that can adjust the body than the coils ...thus not affecting suspension travel...

I don't see how. There is only so much plus and minus travel that can be allowed in the shock part of the strut before you hit bump stops or bottom the shock. Even PSS9/10s really only have a limited adjustable range. You CAN physically push it beyond those numbers, but then you are shorting travel in one direction or the other. The official, allowed by Bilstein, not to be exceeded, in italics, underlined, in quotation marks, is 20mm in the front and ONLY 5mm in the rear, and that value has to be within the measured range on the strut body itself. They cannot and will not guarantee a specific desired height. Only state that the heighest is approximately 30mm below stock. The threads are physically there to raise it above or lower it below the allowed range, but they are not supported by the shock itself. They may be height adjustable, but really just barely, and then, really enough to corner balance, with some small height adjustment available. The 5mm rear range is what really shocked me. I did a ton of homework before buying mine, and I NEVER caught that until recently while going over the install instructions from Bilstein for the 20th time! I wonder how many of the issues that people have had with PSS9s are adjusting them out of their correct operating range.

PSS9/PSS10's height adjustment is not independent of shock travel, so YES, you will lose shock travel if you set the PSS9 to max lowest. Unlike JIC, KW, H&R, and of course Moton, Ohlins...where the height adjustment is independent of shock travel so you can set the car to the lowest setting and still have a good range of shock travel. This is one reason why I've been craving going with a "better" coilover system. KW or JIC maybe?

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That seems physically impossible. Unless you meant to say that those shocks maintain their dampening characteristics over a wider range of motion than some other brands, which is a completely different thing from the height adjustment being independent of the travel available at the shock.

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Yes, and it can be substantial. Info from a post I made on 6speed: When you put on the PSS9, you will drop the ride height about an inch from stock already. I seem to recall that this is due to the parts themselves as well as droop (explained shortly). Then you have about ~20mm of adjustment in the front, and ~10mm in the back (check the spec from Bilstein for your car, but it's close to 20/10). But, this needs to be taken in context: For our cars, the PSS9 shock has about 85mm of total travel available. Of this, about 50mm is free travel before it reaches the internal bumpstops. The bumpstops can then can compress about 50mm, giving you a total MAX of about 100mm of shock travel [a little less than 4"]. Why 85mm if the numbers calculate out to 100mm? Well, in use, the internal bumpstop stiffness becomes REALLY high - effectively becoming a solid mount - at around 35mm of compression. So you have an effective operating range of about 85mm, or about 3.35". Well, what does all this mean? With the car resting on the ground, the shock will compress simply do to the weight of the car, i.e., droop. It could be 10mm, but might be as high as 30mm [or so] based on your car weight. So, if you only have 85mm for shock travel, and 30mm is taken up with droop, you get about 20mm of free travel, and 35 of bumpstop travel. 55mm = ~2" of shock travel before you have "no shock" left. On some heavier cars (like the GT2, the weight of the car causes about 50mm of droop, meaning you are ALREADY on the bumpstops! YIKES!] What about simply getting heavier springs so the car doesn't droop? Well, you would have to revalve your shocks to accomodate the springs. It CAN be done though. Another issue you face with the PSS9 system is that adjusting the ride height [any lower] also reduces the PSS9 shock travel distance [as well as preloading the springs]. Using the above example, say you use all of your 20mm adjustment range for the PSS9. Well, you would further reduce your 55mm of shock travel to 35mm (about 1.4"). On virtually any thing but the smoothest roads, 1.4" is not enough shock travel. You WILL feel it, and NOT like it. If you have less droop, you can lower the ride more, but you won't know you've gone too far until you hit that big bump that really jolts the car. The good news is, there IS a happy lowered place where you can get optimal suspension travel without compressing to the bumpstops, but you will need to figure that out based on your car weight and track/road conditions. I had mine lowered about 15mm, but then had to raise them back up 10mm to get it off the bumpstops when at the track. If you get the car all situated and aligned, and THEN realize you are riding the bumpstops, you can raise it up just a bit without really needing to realign it. I forget the amount, but 10mmF/5mmR should be fine. This will simply take out some negative camber and shouldn't screw up the hangling. I hope this mess is factually accurate and helps, lol. -td

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Not only do you have "no shock", you also have "no spring". Well, except for the tire sidewall.

On the other types, which I know nothing about, I can see where, for a price, it is possible to design a strut such that raising or lowering the spring perch would also raise/lower the bottom mounting of the strut itself. Lower the spring and shock together, car gets lower, same travel, within limits of the suspension geometry.

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You're right, and after a quick look it seems that some of the systems out there seem to do just that (JIC, for example). I stand corrected.

ok now i am confused ...and broadened my search to pss9,row030 and jic this why....my current hieght 25.5 all around,but ride is harch on some roads....which i am trying to eliminate.i am shooting for lexus ride at 26 to 26.5inch height............... pss9 at full height will lower car 1inch from 26.5 to 25.5=$2100 row will lower 26.5 to 26 or 25.75=$1100 jic ...has an adjustable lower sleeve that allows shock lowering without affecting susp travel=$2800

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If you think your ride is harsh on some roads with stock (or close to stock) suspension, I do not recommend upgrading to a sport suspension (ROW M030, PSSX, JIC, or anything else). All of these sacrifice comfort for performance - which will result in an even harsher ride. Of course, this assumes your current suspension is operating correctly. You need to move away from "sport" suspensions to get a more comfortable ride. -td [edited]

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h&r springs and sways and bilstein hd ....

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What spring rates? Sway bars don't really affect ride harshness. [edit] FWIW, I run 300(F) and 550(R) springs with my PSS9. I had 170/260 with my ROW M030. The only issue I had was when my car was too low and hitting the PSS9 bumpstops. Otherwise (for me) this spring/suspension setup is completely streetable. [PSS9 run 2 from full stiff] -td

H&R Springs (progressive) 170-210 F / 230-260 R

Tom, Did you put in aftermarket springs on your PSS9s? Any idea what the standard PSS9 rates are?

JIC (linear) soft - 7/10 (393/564) med - 8/12 (450/674) PSS9 (not sure if linear or progressive) 260/515 GT3 Front: 40 N/mm (228.44 lbs/in --> 225 lbs/in) linear Rear: 95 N/mm (542.55 lbs/in --> 550 lbs/in) progressive

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I used the PSS9 springs. IIRC, they are 300/550. GT3 are 228/543. ROW and US M030 are about 170/260, and stock are about 150/200. Maci, YOu are just close to stock and M030 settings: 150/200 is stock, you have 170/230 (which is actually closer to M030 settings). I believe Bilstein HD are also comparable to the M030 shocks. If you start moving to other sport parts like PSS9/10 you will only be making your ride harsher. If you want more comfort you need a softer suspension - not a sport suspension. -td

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TD - you've offered great advice on all manner of suspension issues but I'd disagree with you on the last point. Even though spring rates are higher, my experience going from stock US suspension (not M030) is that the PSS9's are actually a more pleasant ride when set to softer adjustments... this is with a 30mm lower ride height, set at about 5 front (1=hardest) and 4 rear. They're also not too difficult to set without removing wheels - you'll tear your fingers up removing the plastic protective boots on the adjusters in the front, but it's probably a 20 minute job. Also, the car is MUCH more planted at high speed. Regarding cornering, probably slightly better turn-in, more confidence, but it's not really night/day in my opinion. Again, I'm not an expert, just a casual DE'er and generally fast driver on twisty mountain backroads. Also, as you know, I'm also putting in new ARBs and links because I still want to tighten it up a bit more.

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Sorry, I haven't logged on. Doug, take a look at actual pictures of the JIC, H&R, KWs, etc vs. the PSS9/PSS10.

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Yep. I corrected myself above. Thanks!

Yeah, it's one of those things that I wish I knew before getting the PSS9s. That's one reason why the PSS9's cannot be set to GT2 spec. The shock will hit the internal bump stop.

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Good points, but IMO, pleasantness of ride is a subjective test. Some people just don't like anything more than stock. However, most think stock is way too cushy to begin with. I have had stock, ROW M030, and PSS9. To me, PSS9 on full soft rides and performs about like my ROW M030 - although track performance is still better with PSS9 as I had bigger sway bars. But, stock is by far the most luxo-barge ride. Anything over stock is simply compromising comfort for performance. Some folks can immediately tell the difference, others could care less. Personally, I could ride on full stiff all the time and never blink an eye. As for changing the PSS9, the fronts don't even need to be jacked up if you know which direction to turn - just go all the way soft/stiff, and move back a few clicks. The rears are inside the car so it's pretty easy to get those right. This has just as much (perhaps more) to do with ride height as suspension components. Like exhausts, and stereos, suspensions can be difficult to find a good match to your taste. My suggestion to Maci is to get in a bunch of cars with different suspensions and see what works for him. -td

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i only wish but in a year yet to see a Pcar on the road around here...... i am more inclined now to go with row(oem) or jic (adjustable shock).....and both are linear ....... any one running jic................?

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Again, as usual, sage advice on all points, and I agree. Regarding JIC's, while they may be more "adjustable," I've heard they're appreciably more harsh. A great track setup, but definitely more of a compromise for the street than PSS9/10s - again, only from what I've heard... While I don't have a lot of potholes on my local roads, we have railroad tracks - the PSS9s are very solid and much less jarring over most of my venues than even the stock suspension... and I would recommend something like the JICs for a track junkie... the PSS9/10s seem to be a great street shock to me in my past 3 months... my wife didn't even notice. so to me, that was proof enough - haha. Even if I didn't care about track performance, I would say the PSS9's would be a great upgrade from stock. Gotta consider there's a lot to do with dampers and valving - not all about spring rates. Do what you will, lot's of well-sorted options, great thing about these cars. But I've gone too far on suspensions in the past and there's nothing worse than living with a suspension that more harsh than you'd like, need, or want. Feels like a bad paint job from Earl Scheib, a waste of money.... and punishing if it's beyond your tastes. On the other hand, if you don't get the performance you want, that's the other side of that coin.... it's a tough decision and one that can be expensive. Keep us posted...

I'll interject some data points here, as I've had PSS9's on 2 of my past cars (1 on a E36 BMW, the other on my old 996) as in both cases, depending on the shock valve setting both cars I had rode better than the stock setup. Subjective as that maybe, the key thing to remember here is that regardless of the spring rate, the shock valving must be matched to the spring rate and in the case of the Pss9's they are. This is how the net effect of increasing spring rates can feel just as comfortable or better than the stock setup with substantially lower spring rates. I've ridden in cars with 900lb+ spring rates and with correctly valved shocks/struts, they rode just fine and I have an extremely sensitive back. Case in point as I'm not sure what stock spring rates for the 996 are I'll use my old E36 as the example, had ~120 springs and stock shocks, but BMW is notorious for setting up their shocks to too much compression resistance so the initial hit on a BMWs is a bit harsh so the car resists allowing the wheel to travel upward to soak up the bump but the soft spring rate allows for quite a bit of roll. With the PSS9 Setup (~300 front and ~350 rear), the compression and rebound are controlled much more precisely, the suspension much more effectively damps bumps but offers superior roll resistance and also dramatically reduces brake dive and acceleration squat. With regards to the suspension travel, you will loose a bit of travel in either compression or droop depending on the ride height setting you pick as compared to stock. Is it detrimental to driving? In most cases no unless you choose extremes of either high or low ride height. As mentioned before, too low and you do not have a lot of compression travel to soak up the bump and will hit the bumpstop a lot. Over time this will damage suspension components (depending on the severity of the bumps and you will end up with less control of your car in high performance situations. Too high and you don't have a lot of droop travel and can lift a wheel on gas station and other entrances. The ideal setup is somewhere in the center of the pistons travel in either direction. IMHO the PSS9's are one of the best street/autocross/track setups if your car is a multipurpose car. There are obviously better setups for dedicated track but that is another discussion as that's not what the OP had targeted. I hope this helps,

thanks everyone! after considering all ur inputs and my driving needs and talking to sunset and 2 porsche dealers here in minneapolis....i decided to go with oem row030 from sunset ... thanks again. ps ....now my h&r springs(unknown milage),h&r sways(less than 200miles) and bilsteins hd(less than 200 miles) will be available for sale.....pm me if interested.....