996 suspension

[pchassis]

would like some info on the correct ride height and where on the chassis or the pivot points to measure from

Mark

[Loren]

:welcome:

[pchassis]

:welcome:

Loren, Thanks that chart helps a lot. It's nice to fine someone with good info

on a forum. Some forums I have read seem to be off the wall if you know what

I mean.

Thaks again!

Mark

pchassis

[Doug996InKC]

I too have PSS9s. My wheels are Champion Motorsport 19" RG5 (staggered). Loren should I use the X74 specs, even though they're 19" wheels? Thx!

Edited November 9, 2008 by Doug996InKC

[Loren]

I too have PSS9s. My wheels are Champion Motorsport 19" RG5 (staggered). Loren should I use the X74 specs, even though they're 19" wheels? Thx!

You will never find specs for the 19" wheels on a 996 series car because Porsche does not approve them.

You could use the 997 specs but that would be a little misleading also because 997 has a stiffer chassis than 996.

I think that would depend on where the PSS9's are set for ride height. If you are 30 mm below stock then use the X74 settings.

Otherwise you will likely have to adjust to the ride height, and guess the settings that work best.

[ahamay]

You will never find specs for the 19" wheels on a 996 series car because Porsche does not approve them.

You could use the 997 specs but that would be a little misleading also because 997 has a stiffer chassis than 996.

I think that would depend on where the PSS9's are set for ride height. If you are 30 mm below stock then use the X74 settings.

Otherwise you will likely have to adjust to the ride height, and guess the settings that work best.

hello people

i use 19' techart on my c2 996 and i have noticed that 997 with same 19' techart have almost identical ride height but feel more stable on the road and especially in high speed corners and even if it is the same ride height the 997 had reduced the oversteer feeling at minimum despite the 996 wich still have a lot...

Loren what is your opinion about wheel alignment numbers,should the 997 numbers work better for 996 then the gt3 2004 numbers?

[996noob]

:welcome:

Loren, Thanks that chart helps a lot. It's nice to fine someone with good info

on a forum. Some forums I have read seem to be off the wall if you know what

I mean.

Thaks again!

Mark

pchassis

Loren,

Could you advise where to measure from in order to attain teh ride height value from the specs?

Thanks!

[Loren]

:welcome:

Loren, Thanks that chart helps a lot. It's nice to fine someone with good info

on a forum. Some forums I have read seem to be off the wall if you know what

I mean.

Thaks again!

Mark

pchassis

Loren,

Could you advise where to measure from in order to attain teh ride height value from the specs?

Thanks!

It is the last paragraph on the specs list above.

[perryinva]

Since this got resurrrected, I'll just point out that these readings are with new tires at recommended inflation. Worn tires alone will vary this up to (the following was a brain fart, and is totally wrong, and I apologize for that - I KNOW tire tread is 7/32" not 7/10", so this SHOULD read 0.22", or 5.5mm NOT, 18mm LESS (7/10s of an inch), plus all tires from different makers are NOT the same diameter, even for the same size. This is just one minor spec of the "N" rated vs non-"N" rated tire specs.

In addition, it is a grave misnomer to conclude that PSS9's are the same type height "adjustable" as true adjustables like JICs or Motons. This is not true at all. There is a strict allowable range set by Bilstein, if you want the strut to perform as designed. Many have called the PSS9s junk because they were trying to force the strut to perform outside it's recommended range, simply because it is possible to adjust the spring to that location. They are a great improvement over stock, within the limits prescribed by Bilstein, which is one of the reasons they are so much less than Moton or JIC. SO the charts above are of very limited FYI use when installing PSS9s...you CAN"T just choose the height you want to ride at, you can only choose "a little higher in the Bilsein range or a little lower". The installation instructions are crystal clear on this. There is only a 5mm range of adjustment for the rears, you start about 30mm lower than stock and can only go down to about 35mm, in the front. The start point is car dependent. Remember Porsches spec for the springs is + or - 10mm!!. If your car runs naturally higher due to spring tolerance, then you may find it 35 or 40mm lower to start. If your car runs lower, then it will lower less, as you are replacing the inconsistent stock springs with the consistent Bilstein ones. The 5mm is primarily for corner balancing, not for ride height. While the fronts start about 30mm lower and allow adjustment of 20mm lower from there, the rear hasn't that range, and sort of deyermines wher he fronts will end up. According to the PSS9 "expert" at Bilstein I spoke with, this is to allow adjustment for different front spoiler heights, rake, and corner balancing. The fronts require more height adjustment to "move" the same weight frontward or rearward, than the rears, due to the heavy rear bias on the 911. They are designed to be installed near the center of each range. I had called them because I thought it odd that the fronts had 20mm adjustment vs the 5mm in the rear. The rear height is more critical due to the rear engine RWD design of the 911, and the PSS9 is designed to be in it's best range when installed accordingly. They make 1.5mm thick spring isolator "kits" (read big fat blue plastic washers) that allow you to add a little height if need be, and fix the spring windup clunk that sometimes occurs on the front struts in slow turns.My $0.02.

Edited June 27, 2013 by perryinva

[Benjamin Choi]

Since this got resurrrected, I'll just point out that these readings are with new tires at recommended inflation. Worn tires alone will vary this up to 18mm LESS (7/10s of an inch), plus all tires from different makers are NOT the same diameter, even for the same size. This is just one minor spec of the "N" rated vs non-"N" rated tire specs. It is hard to correctly calculate what the height should be, as you can't just add tire wear, because the tire flattens. It is probably closer to .75 of tire wear.

In addition, it is a grave misnomer to conclude that PSS9's are the same type height "adjustable" as true adjustables like JICs or Motons. This is not true at all. There is a strict allowable range set by Bilstein, if you want the strut to perform as designed. Many have called the PSS9s junk because they were trying to force the strut to perform outside it's recommended range, simply because it is possible to adjust the spring to that location. They are a great improvement over stock, within the limits prescribed by Bilstein, which is one of the reasons they are so much less than Moton or JIC. SO the charts above are of very limited FYI use when installing PSS9s...you CAN"T just choose the height you want to ride at, you can only choose "a little higher in the Bilsein range or a little lower". The installation instructions are crystal clear on this. There is only a 5mm range of adjustment for the rears, you start about 25mm lower than stock and can only go down to about 30mm. The start point is car dependent. Remember Porsches spec for the springs is + or - 10mm!!. If your car runs naturally higher due to spring tolerance, then you may find it 30 or 35mm lower to start. If your car runs lower, then it will lower less, as you are replacing the inconsistent stock springs with the consistent Bilstein ones. The 5mm is primarily for corner balancing, not for ride height. The fronts also start about 25mm lower but allow adjustment of 20mm lower from there. According to the PSS9 "expert" at Bilstein I spoke with, this is to allow adjustment for different front spoiler heights, rake, and corner balancing. The fronts require more height adjustment to "move" the same weight frontward or rearward, than the rears, due to the heavy rear bias on the 911. They are designed to be installed near the center of each range. I had called them because I thought it odd that the fronts had 20mm adjustment vs the 5mm in the rear. The rear height is more critical due to the rear engine RWD design of the 911, and the PSS9 is designed to be in it's best range when installed accordingly. They make 1.5mm thick spring isolator "kits" (read big fat blue plastic washers) that allow you to add a little height if need be, and fix the spring windup clunk that sometimes occurs on the front struts in slow turns.

My $0.02.

preach perry preach! well done

[996noob]

:welcome:

Loren, Thanks that chart helps a lot. It's nice to fine someone with good info

on a forum. Some forums I have read seem to be off the wall if you know what

I mean.

Thaks again!

Mark

pchassis

Loren,

Could you advise where to measure from in order to attain teh ride height value from the specs?

Thanks!

It is the last paragraph on the specs list above.

Loren,

I know it is in the last paragraph for the Front and Rear specs, respectively. But what does it mean? How do we interpret it? It doesn't seem obvious to me. "Tension Strut" doesn't even seem to be mentioned in the Parts Catalog as a description of any part, and I have trouble looking for the "hexagon-head bolt (a/f 18)".

And for the rear, what does the "locating bore" look like?

I know that Porsche describes it as such, but it isn't always easy to understand, perhaps it's a translation from German, or that how it's phrased in German, but that's why we are on this forum, to help each other out, right?

I hope you understand what I'm trying to say, and I hope that someone can help.

[Loren]

[996noob]

Since this got resurrrected, I'll just point out that these readings are with new tires at recommended inflation. Worn tires alone will vary this up to 18mm LESS (7/10s of an inch), plus all tires from different makers are NOT the same diameter, even for the same size. This is just one minor spec of the "N" rated vs non-"N" rated tire specs. It is hard to correctly calculate what the height should be, as you can't just add tire wear, because the tire flattens. It is probably closer to .75 of tire wear.

In addition, it is a grave misnomer to conclude that PSS9's are the same type height "adjustable" as true adjustables like JICs or Motons. This is not true at all. There is a strict allowable range set by Bilstein, if you want the strut to perform as designed. Many have called the PSS9s junk because they were trying to force the strut to perform outside it's recommended range, simply because it is possible to adjust the spring to that location. They are a great improvement over stock, within the limits prescribed by Bilstein, which is one of the reasons they are so much less than Moton or JIC. SO the charts above are of very limited FYI use when installing PSS9s...you CAN"T just choose the height you want to ride at, you can only choose "a little higher in the Bilsein range or a little lower". The installation instructions are crystal clear on this. There is only a 5mm range of adjustment for the rears, you start about 25mm lower than stock and can only go down to about 30mm. The start point is car dependent. Remember Porsches spec for the springs is + or - 10mm!!. If your car runs naturally higher due to spring tolerance, then you may find it 30 or 35mm lower to start. If your car runs lower, then it will lower less, as you are replacing the inconsistent stock springs with the consistent Bilstein ones. The 5mm is primarily for corner balancing, not for ride height. The fronts also start about 25mm lower but allow adjustment of 20mm lower from there. According to the PSS9 "expert" at Bilstein I spoke with, this is to allow adjustment for different front spoiler heights, rake, and corner balancing. The fronts require more height adjustment to "move" the same weight frontward or rearward, than the rears, due to the heavy rear bias on the 911. They are designed to be installed near the center of each range. I had called them because I thought it odd that the fronts had 20mm adjustment vs the 5mm in the rear. The rear height is more critical due to the rear engine RWD design of the 911, and the PSS9 is designed to be in it's best range when installed accordingly. They make 1.5mm thick spring isolator "kits" (read big fat blue plastic washers) that allow you to add a little height if need be, and fix the spring windup clunk that sometimes occurs on the front struts in slow turns.

My $0.02.

That is very good info. However, for my set of PSS9's, it doesn't say where "start point" is. It seems as though I would have to just set a position of the spring perches and then install, and see what ride height I land on. I wouldn't want to set the height outside of the working range of the shock absorber, that's for sure. I'm not looking to slam my car down, I actually want only 25mm of lowering. If Bilstein says that their PSS9 set lowers from 25mm, how do I determine this start point? Is it when the perches are at the very top end of the threaded portion? The fact that I could even ask this question can only mean that I am going in "blind". It may very well be that the very top of the thread is the wrong position, and I don't even know! The instructions that came in the box are very brief, and not specific.

I welcome any advice from anyone who has installed them.

Thank you.

Edited July 24, 2009 by 996noob

[996noob]

Loren,

All I can say is... Fantastic. You have made my day.

Thank you. I really appreciate it.

[perryinva]

Send me your email address. I will send you a pdf of the PSS9 instructions if you don't have them. They are pretty clear as to where you can adjust the spring perches for the strut springs. If you have the diagram that shows the parts breakdown for the front and rear struts, it shows where on the strut you measure (top of each spring perch to either center of bracket (F) or mounting hole ®). You must keep the perches in the specified range..it has NOTHING to do with the height of the car on the above charts. You car will end up where it ends up...that was the point of my post. SO you can adjust them to either the top, middle or bottom of the Bilstein designed range..I recommend the middle, and then install them. Or you can lower the perches all the way down to make installation easier, then adjust them back up to where they belong. You CANNOT "adjust your car 25mm lower" than it was, unless you car was(is) at the normal stock heights, ie 158mm front and 163mm rear for a C2 with 18" wheels. Then, because Bilstein has designed the struts to drop your car about 25mm, you will end up there. My car, with stock setup, is lower both F&R on stock struts, so my PSS9s, do not lower it 25mm. In GENERAL, the car will (can) be from 15 mm lower (if your car was at the bottom of the accepatable range from Porsche on OE springs, or around 26" from fender lip to ground) to as much as 45mm lower (if you were at the top of the acceptable range, or a fender lip around 27"), but you CAN"T adjust them to anywhere within that range, you can only very minorly (is that a word?) adjust them about 5mm within the range that they end up in. The fronts have +- 10mm of adjustment and the rears have +- 2.5mm, most of it primarily for corner balancing. Now you CAN use the illustrated measuring poins to rough in the corner balance of the struts, get both L&R sides even, and then get the fronts and rears proportional to each other, using the X73 or X74 numbers as a basis. Does this clarify it for you?

Edited July 24, 2009 by perryinva

[996noob]

Send me your email address. I will send you a pdf of the PSS9 instructions if you don't have them. They are pretty clear as to where you can adjust the spring perches for the strut springs. If you have the diagram that shows the parts breakdown for the front and rear struts, it shows where on the strut you measure (top of each spring perch to either center of bracket (F) or mounting hole ®). You must keep the perches in the specified range..it has NOTHING to do with the height of the car on the above charts. You car will end up where it ends up...that was the point of my post. SO you can adjust them to either the top, middle or bottom of the Bilstein designed range..I recommend the middle, and then install them. Or you can lower the perches all the way down to make installation easier, then adjust them back up to where they belong. You CANNOT "adjust your car 25mm lower" than it was, unless you car was(is) at the normal stock heights, ie 158mm front and 163mm rear for a C2 with 18" wheels. Then, because Bilstein has designed the struts to drop your car about 25mm, you will end up there. My car, with stock setup, is lower both F&R on stock struts, so my PSS9s, do not lower it 25mm. In GENERAL, the car will (can) be from 15 mm lower (if your car was at the bottom of the accepatable range from Porsche on OE springs, or around 26" from fender lip to ground) to as much as 45mm lower (if you were at the top of the acceptable range, or a fender lip around 27"), but you CAN"T adjust them to anywhere within that range, you can only very minorly (is that a word?) adjust them about 5mm within the range that they end up in. The fronts have +- 10mm of adjustment and the rears have +- 2.5mm, most of it primarily for corner balancing. Now you CAN use the illustrated measuring poins to rough in the corner balance of the struts, get both L&R sides even, and then get the fronts and rears proportional to each other, using the X73 or X74 numbers as a basis. Does this clarify it for you?

Crystal clear. Basically, I'll set the PSS9's in the middle range as a start point, install on car, see where I land in terms of ride height, then adjust the heights to, say, X74 specs, should I choose that as a reference, keeping in mind that I should not deviate out of the range that Bilstein has set on the strut perch adjustment range.

In essence, I should only be adjusting within Bilstein's range. I'll only use Porsche specs as a guide to alignment.

I've sent you a PM with my email address. I'll compare your instructions to mine. I think my instructions are incomplete, or some early version.

[perryinva]

No problem, you've got it exactly right now...you understand it now more than 95% of the others!! I'll send you the pdf for the PSS9 and PSS10s, they are the same except the 10s have a much better diagram showing exactly what parts you can/have to re-use. (and the firmness adjustment knobs are different and backwards from each other...follow the PSS9 knob instructions). I'm putting together a pictorial instruction for the PSS9 installations, but it will be a few weeks beofre I really have the time to finish it up.

[996noob]

No problem, you've got it exactly right now...you understand it now more than 95% of the others!! I'll send you the pdf for the PSS9 and PSS10s, they are the same except the 10s have a much better diagram showing exactly what parts you can/have to re-use. (and the firmness adjustment knobs are different and backwards from each other...follow the PSS9 knob instructions). I'm putting together a pictorial instruction for the PSS9 installations, but it will be a few weeks beofre I really have the time to finish it up.

I've successfully installed the PSS9 on my 996. Setting the coilovers at the highest level within Bilstein's prescribed range, I landed on a ride height of 113mm Front and 135mm Rear, measured from the points prescribed by Porsche according to Loren's digrams, done after alignment. As the heights were close to X74 specs, I chose to run the X74 alignment specs. The only spec I could not get was the front camber. The most vertical I could get was half a degree negative on the left and 1 degree negative on the right. Would I be better off running half degree left and one degree right, or if I evened it out at one degree each side? I figured that in the end I should consider the Total Camber by adding them up, in this case one and a half degress, that's why I chose to keep half left and one right at that time. What do you think?

[perryinva]

WOW, 113mm front with the PSS9s at the highest level!!! That's 44mm lower than stock or 1 3/4"!!! Are you SURE? That is LOW. I'd never get out of my driveway if mine got lowered that much when I put on the PSS9s. The rear on your car at 28 mm lower or 1 1/8" is right on the 30mm that Bilstein specs (I thought it was 25mm, but I checked again and they spec 30mm.) What are your fender lip to ground measurements, in inches? I'd always make both sides camber even, but you HAVE to do it with weight in the drivers seat. Pics would be GREAT!!

Edited August 11, 2009 by perryinva

[996noob]

WOW, 113mm front with the PSS9s at the highest level!!! That's 44mm lower than stock or 1 3/4"!!! Are you SURE? That is LOW. I'd never get out of my driveway if mine got lowered that much when I put on the PSS9s. The rear on your car at 28 mm lower or 1 1/8" is right on the 30mm that Bilstein specs (I thought it was 25mm, but I checked again and they spec 30mm.) What are your fender lip to ground measurements, in inches? I'd always make both sides camber even, but you HAVE to do it with weight in the drivers seat. Pics would be GREAT!!

Here is the side view pic of the car after lowering.

I was wondering, if, since the final ride height is so low, as compared to many other 996's with PSS9's, the shock must be working in it's "lower" than normal position, in this specific case, would it be then allowable to raise the height above Bilstein's spec on the shock? Just wondering....

[Doug996InKC]

I'm putting together a pictorial instruction for the PSS9 installations, but it will be a few weeks beofre I really have the time to finish it up.

Wow, a lot of educational material has surfaced since my posting on this thread. Perry, did you end up posting a PSS9 installation pictorial? If so, please share. If not, could you please email me Bilstein's instructions? Sending you a PM with my email address. Thanks!

[perryinva]

WOW, 113mm front with the PSS9s at the highest level!!! That's 44mm lower than stock or 1 3/4"!!! Are you SURE? That is LOW. I'd never get out of my driveway if mine got lowered that much when I put on the PSS9s. The rear on your car at 28 mm lower or 1 1/8" is right on the 30mm that Bilstein specs (I thought it was 25mm, but I checked again and they spec 30mm.) What are your fender lip to ground measurements, in inches? I'd always make both sides camber even, but you HAVE to do it with weight in the drivers seat. Pics would be GREAT!!

Here is the side view pic of the car after lowering.

I was wondering, if, since the final ride height is so low, as compared to many other 996's with PSS9's, the shock must be working in it's "lower" than normal position, in this specific case, would it be then allowable to raise the height above Bilstein's spec on the shock? Just wondering....

Absolutely correct, IMHO. Whatever the reason, your strut is operating closer to bottomed out by roughly 10mm, or a bit over 3/8"". Doesn't sound like much, but as a percentage of overall range, it is. I'd raise it between 1/4 & 3/8" or 7-9mm, which would still give you a positive rake, keep the designed fore/aft height relationship, and would help your camber settings as well. You shouldn't need another alignment, either for sucha small change. What were your starting numbers?

Edited August 17, 2009 by perryinva

[996noob]

WOW, 113mm front with the PSS9s at the highest level!!! That's 44mm lower than stock or 1 3/4"!!! Are you SURE? That is LOW. I'd never get out of my driveway if mine got lowered that much when I put on the PSS9s. The rear on your car at 28 mm lower or 1 1/8" is right on the 30mm that Bilstein specs (I thought it was 25mm, but I checked again and they spec 30mm.) What are your fender lip to ground measurements, in inches? I'd always make both sides camber even, but you HAVE to do it with weight in the drivers seat. Pics would be GREAT!!

Here is the side view pic of the car after lowering.

I was wondering, if, since the final ride height is so low, as compared to many other 996's with PSS9's, the shock must be working in it's "lower" than normal position, in this specific case, would it be then allowable to raise the height above Bilstein's spec on the shock? Just wondering....

Absolutely correct, IMHO. Whatever the reason, your strut is operating closer to bottomed out by roughly 10mm, or a bit over 3/8"". Doesn't sound like much, but as a percentage of overall range, it is. I'd raise it between 1/4 & 3/8" or 7-9mm, which would still give you a positive rake, keep the designed fore/aft height relationship, and would help your camber settings as well. You shouldn't need another alignment, either for sucha small change. What were your starting numbers?

Unfortunately, my start numbers were measured from the ground to the jack points, since at that time, I did not know where to measure from until Loren gave us the diagram. Thanks Loren. I could theoretically transpose and approximate the start numbers to the correct points by measuring the current heights of the jack points. Give me a few days, the car is in the paint shop getting a new coat.

The reason I resurrected this thread is because I seriously think my car is much lower than it out to be with the PSS9's. I can't begin to guess why. But, I think that I should raise the car to at or around the correct "working" position of the shock absorbers, as I'm sure I'm closer to bottoming out position and have less workable range during driving, and this is where I need your help and advice.

That being said, I also have a question about the camber. Obviously, with the lowering, I am getting more negative camber than before. I also know that most of you who run the GT3 lower arms intend to dial in more negative camber for track or autoX. What if I installed the GT3 arms so that I could get more positive camber? Is this possible? I do not know the shortest length of the GT3 arm, but if it is shorter than stock, theoretically I could do this. Then I could adjust more camber for track (unfortunately, only once a year for me!).

[Mr. Batman]

Since this got resurrrected, I'll just point out that these readings are with new tires at recommended inflation. Worn tires alone will vary this up to 18mm LESS (7/10s of an inch), plus all tires from different makers are NOT the same diameter, even for the same size. This is just one minor spec of the "N" rated vs non-"N" rated tire specs. It is hard to correctly calculate what the height should be, as you can't just add tire wear, because the tire flattens. It is probably closer to .75 of tire wear.In addition, it is a grave misnomer to conclude that PSS9's are the same type height "adjustable" as true adjustables like JICs or Motons. This is not true at all. There is a strict allowable range set by Bilstein, if you want the strut to perform as designed. Many have called the PSS9s junk because they were trying to force the strut to perform outside it's recommended range, simply because it is possible to adjust the spring to that location. They are a great improvement over stock, within the limits prescribed by Bilstein, which is one of the reasons they are so much less than Moton or JIC. SO the charts above are of very limited FYI use when installing PSS9s...you CAN"T just choose the height you want to ride at, you can only choose "a little higher in the Bilsein range or a little lower". The installation instructions are crystal clear on this. There is only a 5mm range of adjustment for the rears, you start about 30mm lower than stock and can only go down to about 35mm, in the front. The start point is car dependent. Remember Porsches spec for the springs is + or - 10mm!!. If your car runs naturally higher due to spring tolerance, then you may find it 35 or 40mm lower to start. If your car runs lower, then it will lower less, as you are replacing the inconsistent stock springs with the consistent Bilstein ones. The 5mm is primarily for corner balancing, not for ride height. While the fronts start about 30mm lower and allow adjustment of 20mm lower from there, the rear hasn't that range, and sort of deyermines wher he fronts will end up. According to the PSS9 "expert" at Bilstein I spoke with, this is to allow adjustment for different front spoiler heights, rake, and corner balancing. The fronts require more height adjustment to "move" the same weight frontward or rearward, than the rears, due to the heavy rear bias on the 911. They are designed to be installed near the center of each range. I had called them because I thought it odd that the fronts had 20mm adjustment vs the 5mm in the rear. The rear height is more critical due to the rear engine RWD design of the 911, and the PSS9 is designed to be in it's best range when installed accordingly. They make 1.5mm thick spring isolator "kits" (read big fat blue plastic washers) that allow you to add a little height if need be, and fix the spring windup clunk that sometimes occurs on the front struts in slow turns.My $0.02.

. Where are you getting tires with tread that's 1" deep? Sport tires usually have tread depths of 10/32" when new.

[perryinva]

You are quite correct, that should have read 7/32nds not 7/10ths! Don't know what I was thinking, maybe because mm is base 10? Do they measure truck tires in tenths? Not sure, but, yes, that should have read 7/32nds of an inch or about 0.25" (about 6mm, not 18mm!) not 0.75" Doh!

Of course the point is still valid, that tread depth, overall actual diameter and tire squat vary from manufacturer to manufacturer, and adding worn tires will vary the ride height measurement, so you have to be careful when looking at the measurement points.