Bilstein PSS10 Height Calculation
#1
Bilstein PSS10 Height Calculation
I am trying to install new Bilstein PSS10s on my car and am uncertain how to go about setting the height. I understand how to turn the spring plates with the supplied wrenches, but if I am trying to get the car to a certain height, how does that translate to me figuring out where to adjust the spring plates to? Do I adjust the height prior to install or do I do it after installing them? I don't see any numbers on the shocks that allow one to calculate height.
Hope this question makes sense. This project is my first "major" mechanical upgrade on my car. Don't want to screw up my first job.
Thanks for any help. If I need to clarify the question, let me know.
Hope this question makes sense. This project is my first "major" mechanical upgrade on my car. Don't want to screw up my first job.
Thanks for any help. If I need to clarify the question, let me know.
Last edited by p911enthusiast; 07-27-2013 at 12:56 PM.
#2
I apologize in advance for the lack of pictures; I'm on vacation without laptop.
Essentially you will adjust the threaded collars on each shock to achieve a specific height as measured from the ground to specific points. I have set mine at RS height, but there's a table floating around that will show you all recommended heights ( c4s, RS, ROW, etc.). As for the exact measuring points do a search on either this board or Pelican.
After install allignment, corner weighing, and balance.
Essentially you will adjust the threaded collars on each shock to achieve a specific height as measured from the ground to specific points. I have set mine at RS height, but there's a table floating around that will show you all recommended heights ( c4s, RS, ROW, etc.). As for the exact measuring points do a search on either this board or Pelican.
After install allignment, corner weighing, and balance.
#3
Thanks - another question
Thanks for the reply. Hope your vacation is going well.
I have downloaded the height chart from the web. Let's say I want a front height of 154 - how do I know where to adjust the thread collars to. Do I adjust them prior to installing them, or am I able to adjust them once they are on the car. If I'm able to adjust them while they are on the car, can I do it with the car lowered or does it need to be jacked up when adjusting them?
thanks in advance.
I have downloaded the height chart from the web. Let's say I want a front height of 154 - how do I know where to adjust the thread collars to. Do I adjust them prior to installing them, or am I able to adjust them once they are on the car. If I'm able to adjust them while they are on the car, can I do it with the car lowered or does it need to be jacked up when adjusting them?
thanks in advance.
#4
Rennlist Member
You can adjust them when they are on the car, but you will need to jack up each corner, remove the wheel to access the perch, adjust based on your measurements, and repeat.
If you are having a competent shop install the C/Os, Im sure they can help you with correct perch settings for a desired stance.
If you are having a competent shop install the C/Os, Im sure they can help you with correct perch settings for a desired stance.
#6
https://rennlist.com/forums/993-foru...ll-height.html
Note, target in above thread is RS +10mm, i.e. ROW M030 -10mm (aka US M032 -40mm) or 134mm front / 117mm rear. This looks cool but you might want to increase by 10-20mm for general around town use, especially if you have a steep driveway or similar.
The motion ratios are approx 0.75 front & 0.90 rear, i.e. 10mm of movement in the front spring = 7.5mm of wheel travel.
From experience, if you match the spring perch heights carefully, you're very likely to end up within the tolerance of acceptable corner weights. Align & drive it a bit to let things settle before fine tuning.
Note, target in above thread is RS +10mm, i.e. ROW M030 -10mm (aka US M032 -40mm) or 134mm front / 117mm rear. This looks cool but you might want to increase by 10-20mm for general around town use, especially if you have a steep driveway or similar.
The motion ratios are approx 0.75 front & 0.90 rear, i.e. 10mm of movement in the front spring = 7.5mm of wheel travel.
From experience, if you match the spring perch heights carefully, you're very likely to end up within the tolerance of acceptable corner weights. Align & drive it a bit to let things settle before fine tuning.
#7
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
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On key spot to look for - make sure the rear sway bar link is not contacting the toe control arm when the car is in the air - the means your sway bar bracket is too low.
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#9
Instructor
Hey guys, have you seen discussions about Bilstein's recommended minimum ride height for PSS10 on a 993? I've seen something on a 996 thread that the shocks don't behave optimally outside of a ride height range. I suspect my ride height is too low. It's lower in the rear for sure and the car looks a bit like it's leaning back. I can imagine how that affects drag and interferes with downward force.
How is ride height typically measured? I'll get the car on a lift this weekend and can measure positions on the shocks themselves.
I'm observing very strange behavior when the front and rear stiffness difference is greater than 2, and it's not just strange bobbing. Under load, there's actual acceleration hesitation that lasts more than just a couple of lugging-like pulls. At front 5 rear 6, or front 5 rear 4, this isn't so noticeable. Otherwise, it is. Has anyone experienced the suspension affecting throttle response this way? As an aside, I've been trying to fix this hesitation, and I've gotten along quite far by replacing sagging engine mounts with RS ones, and a new fuel pump.
How is ride height typically measured? I'll get the car on a lift this weekend and can measure positions on the shocks themselves.
I'm observing very strange behavior when the front and rear stiffness difference is greater than 2, and it's not just strange bobbing. Under load, there's actual acceleration hesitation that lasts more than just a couple of lugging-like pulls. At front 5 rear 6, or front 5 rear 4, this isn't so noticeable. Otherwise, it is. Has anyone experienced the suspension affecting throttle response this way? As an aside, I've been trying to fix this hesitation, and I've gotten along quite far by replacing sagging engine mounts with RS ones, and a new fuel pump.
#10
Three Wheelin'
Hey guys, have you seen discussions about Bilstein's recommended minimum ride height for PSS10 on a 993? I've seen something on a 996 thread that the shocks don't behave optimally outside of a ride height range. I suspect my ride height is too low. It's lower in the rear for sure and the car looks a bit like it's leaning back. I can imagine how that affects drag and interferes with downward force.
How is ride height typically measured? I'll get the car on a lift this weekend and can measure positions on the shocks themselves.
I'm observing very strange behavior when the front and rear stiffness difference is greater than 2, and it's not just strange bobbing. Under load, there's actual acceleration hesitation that lasts more than just a couple of lugging-like pulls. At front 5 rear 6, or front 5 rear 4, this isn't so noticeable. Otherwise, it is. Has anyone experienced the suspension affecting throttle response this way? As an aside, I've been trying to fix this hesitation, and I've gotten along quite far by replacing sagging engine mounts with RS ones, and a new fuel pump.
How is ride height typically measured? I'll get the car on a lift this weekend and can measure positions on the shocks themselves.
I'm observing very strange behavior when the front and rear stiffness difference is greater than 2, and it's not just strange bobbing. Under load, there's actual acceleration hesitation that lasts more than just a couple of lugging-like pulls. At front 5 rear 6, or front 5 rear 4, this isn't so noticeable. Otherwise, it is. Has anyone experienced the suspension affecting throttle response this way? As an aside, I've been trying to fix this hesitation, and I've gotten along quite far by replacing sagging engine mounts with RS ones, and a new fuel pump.
From a 2009 Bill Verburg post:
I suspect you saw this over on Pelican
993 measuring points
and specs
You notice that there is a +/- ?
you want the front lower than the back for aero benefits, you want to keep as much air from going under the car as is possible.
Nose up is bad, nose down is good, high is bad low is good
1) whats normal? Its not good though. Drop the front so that the fender height is about the same or maybe a tad lower than the rear fender
2) You can measure rake on the door sil as yuou have done
993 measuring points
and specs
You notice that there is a +/- ?
you want the front lower than the back for aero benefits, you want to keep as much air from going under the car as is possible.
Nose up is bad, nose down is good, high is bad low is good
1) whats normal? Its not good though. Drop the front so that the fender height is about the same or maybe a tad lower than the rear fender
2) You can measure rake on the door sil as yuou have done
The last thing I did was to adjust ride height. My goal was RS +10, or specifically 134mm front and 117mm rear when measured as specified in the workshop manual (full tank of gas, from the correct points on the car, etc). I was able to get it +/- 1mm of those numbers on my very unscientific garage floor. I decided to not get it perfect since it's going to be professionally corner balanced anyway.
Not too many pictures here as there's not much to see. I started by using a bolt and coupling nut like an an adjustable feeler gauge to measure the height at each corner.
In this case, I was 124mm, or 10mm lower than my target height in the front.
So, I used the wrenches included with the PSS10 kit to spin the spring perch up or down (depending on my measurements). You can ignore the yellow lines I put on the shock. I didn't end up using them for anything.
At this point, it was just trial and error until I got the car where I wanted it. I would use a floor jack to raise an axle at a time, remove the wheels, adjust, reinstall the wheels, lower then roll the car a bit before measuring again.
In earlier posts, I mention that I set the initial spring perches to the middle of their range as documented in the PSS10 installation instructions that come with the kit. This put me at:
Left Front - 124mm
Right Front 127mm
Left rear - 125mm
Right rear - 125mm
So, overall, I had to raise the front end roughly 10mm and lower the back 8mm to hit my target ride height.
Not too many pictures here as there's not much to see. I started by using a bolt and coupling nut like an an adjustable feeler gauge to measure the height at each corner.
In this case, I was 124mm, or 10mm lower than my target height in the front.
So, I used the wrenches included with the PSS10 kit to spin the spring perch up or down (depending on my measurements). You can ignore the yellow lines I put on the shock. I didn't end up using them for anything.
At this point, it was just trial and error until I got the car where I wanted it. I would use a floor jack to raise an axle at a time, remove the wheels, adjust, reinstall the wheels, lower then roll the car a bit before measuring again.
In earlier posts, I mention that I set the initial spring perches to the middle of their range as documented in the PSS10 installation instructions that come with the kit. This put me at:
Left Front - 124mm
Right Front 127mm
Left rear - 125mm
Right rear - 125mm
So, overall, I had to raise the front end roughly 10mm and lower the back 8mm to hit my target ride height.
#11
Three Wheelin'
This is will have no bearing on throttle response however.