PBenz

From US stock, to PSS9/TRG, to M033/Bilstein HD with stock sways - I think I've finally found the perfect combination of ride quality and good looks that suits my personal taste. If anyone is interested in picking up a set of PSS9s/TRG sways with exactly 5,492 miles on them, I've decided to list them on eBay - starting bid $1500, "buy it now" price $2000.

I'd also like to take this opportunity to talk a bit about ride height and how I measured it. I've seen many posts on this forum that describe ride height as the distance from the floor to the highest arch of the fender. I suppose this is fine for a general point of reference, but this is not how the shop manual describes how to do this. Since I was seeing a difference of 1/2" from side to side in the front when using the floor-to-fender measurement, I set out to find the truth.

This thread contains the diagram from the shop manual. The front measurement is easy enough to figure out, and here's a photo taken from the front of the car that highlights the bolt used to measure the front ride height:



Finding the correct reference point in the rear is a bit more challenging. After carefully examining the diagram, I believe that the highlighted area in this photo, taken from the back of the car looking forward, is what the diagram is referring to:



If I'm wrong, please let me know, but the measurements match up exactly with what I expected. I purchased the M033 springs/struts from Gert (i.e., Carnewal - great vendor, btw), who includes instructions on how to set the locking rings to achieve the desired ride height before you install them on the car. I was VERY careful with this, and I was shooting for the M030 setup, which is called RoW (rest of world) Sport in the shop manual.

Once installed, I used the following equipment to perform the measurement:



The 2 pieces of metal I'm holding in my hand are from a depth micrometer I had in my toolbox from my days as a mechanic ("those days" were 1985-1990, btw). I'm holding them the same way I used them when I did the measurement. I simply held both pieces together and shifted them until the total length of both shafts fit snugly between the floor and the reference point. I then carefully slid my arm out from under the car, and measured the length of the 2 shafts with the vernier caliper you see in the picture. I repeated this process twice to make sure the shafts didn't slip the first time.

Obviously, there are better tools for this! One that would be PERFECT is a small device that you can twist to extend metal shafts on both ends, making it much easier when under the car. I can't think of what this is called at the moment. (An "inside" micrometer?). Regardless, if you're careful, I think you can pretty much use anything to measure your ride height so long as you take the measurements at the correct points under the car.

I've included a picture that shows the difference between the 3 ride heights I went through. The stock US ride height is almost laughable! Off-roading, anyone? The PSS9 ride height is not certain, but it's got to be in the vicinity of the RS spec. I asked the local dealer to set it to RoW, but they didn't touch it. (They also set the camber FURTHER out of spec than how I brought it in, but that's another story). Finally, assuming I took the measurements at the correct locations, then the bottom picture is the RoW Sport setting.



For your reference, here are the RoW Sport specs taken right from the shop manual. All values are in mm:

RoW Sport
Front: 144 +/- 10
Max left-to-right difference: 5

Rear: 127 +/- 10
Max left-to-right difference: 5

Max front to rear difference: 10


I guess my greatest fear in posting this is someone coming along saying: "Sorry, Paul - that's not the correct reference point.". But since everything matches up with Gert's instructions, and since the car is obviously lower than the Stock height and higher than the PSS9 height, I think I did OK. (We'll soon find out, I guess. )

I sincerely hope others will find this information useful, and I'd be happy to answer any questions.

Paul902

Excellent post, Paul.

I used the same measurement technique when I did mine. I used a telescopic section from an old extendable magnet to make the measurement. For sure the underneath points are the way to go, and I like how you highlighted them in your photo.

cheers,

InTheAir

You can also use a paper ruler, available here http://www.vendian.org/mncharity/dir3/paper_rulers/ to cut the end of the ruler flat with the beginning of the scale. This way you can rest the cut end on the flat and level surface below the vehicle and read the height without the need to transfer a measuring stick to a micrometer. Considering that the heights are +/- 10mm, this method can get you well within that range.

Nice pictures, btw.

mkol1248

Two years ago, I also set ride height using the reference points as you did. I had one complication. My garage floor has smooth newlike condition, and looks perfect flat, but it is not. With water level, I found differences on order 5-10 mm. I used some thin plywood under wheels to adjust.

Bull

Excellent job and description!

The measurements to the top of the wheel arches are only useful for quick checks to see if everything is where you want it (a new suspension will usually settle over time). If you want a quick-check method, measure the fender arch now when you have the car set where you need it, then you will have a reference point.

os993

Thank you. Can you please explain why you replaced the PSS9/TRG setup?

PBenz

Sure. It's really very simple - the ride quality was a bit too harsh for my taste. If I planned on going to the track, even as little as once/yr, I might have stuck with it.

If you go through all the old threads on this topic (there are many), you'll find some people that agree that the PSS9s are too harsh for daily use, and others that find the ride "quite pleasant". It really comes down to a matter of personal preference, and how you intend on using the car.

AOW162435

Paul,
Awesome post. Since I have the same setup sitting in a box in the corner of my garage, I found your hints very valuable.

Do you feel that the Carnewal instructions with respect to setting height, are sufficient? In other words, once everything is bolted in properly, should one be able to take the car to a shop for an alignment only - or will they need to mess with the ride heights that I've given them?

To the other Paul - I thought about using an extendable magnet as well for checking the ride heights

Andreas

PBenz

Thanks, Andreas. (And thanks to others for the kind words, as well. I've gotten so much out of this forum, it feels good to finally give a little something back).

I actually screwed up using Gert's instructions by setting the fronts too low by 10mm - I forgot the add 10mm to the "Size Y" figure he gives for RoW M030 - 10mm (I didn't want to go down the extra 10mm. BTW, don't forget that RoW M030 is called RoW Sport in the shop manual). When I let the car down, it looked jacked-up in the back, and I knew something was wrong. Upon discovering my mistake, I whipped out the vernier caliper and raised the fronts very carefully by an equal amount by measuring the distance from the bottom thread on the shock tube to the bottom of the lower locking ring. I did the detailed measurements described in my initial post soon after this.

The rears were setup perfectly, btw, using only Gert's "Size X" value. My measurement came out to 128.3 on both sides, right smack in the middle of the spec. Good thing, because if I'm not mistaken (and I'm sure somebody will correct me if I am), you have to remove the rear strut to alter the ride height. This is one area where the PSS9 system has a clear advantage.

InTheAir

Correct.

friar93

ive had new springs/shocks installed. the shop set them up in what they've described as a race setup with the driver's side noticably higher-about 1/2"- and the right rear even a bit lower than the front. I'm told this is to compensate for the driver's weight. It kind of bothers me and I'm inclined to have the rears set up at the same height on each side.

Any input or opinion on this?

f_scaife

Paul,

could you give us a quick comparison between your stock SUV springs and shocks and your current setup? How much less confidence, (if any) does the M033 setup give you versus the PSS9 TRG setup?

Bull

If they set the corner weights without you, or a very correctly set group of weights, then they are just guessing at it. Corner weighting must be done with the proper weights, and distribution, in the car. Unless you are a Featherweight, the car should not sit completely level in all directions when empty.

PorscheDoc

Very good post. It is a pet peeve of mine when people talk about setting their ride height off the fenders. Always go off the points listed in the shop manuals. At the shop i have a various supply of long bolts cut to approximate size of various ride settings on all the models. I thread 2 nuts on the end, one long, and one regular. The long nut i can screw in and out until the overall length of the bolt is where i want it to be (for example, one bolt has a range of something like 125-135mm, another might have a range from 115-125mm, etc), then i use the other nut to lock the nuts in place and keep them from moving. One any given car, i use one set bolt for the front, and 1 for the rear, set to the exact height i want. Makes setting the ride height much easier than trying to measure everytime you make an adjustment.

kkim

Paul,

Very interesting measuring device! I like it. One suggestion, that might help, would be to have 2 small zip ties around the two rods so that you could telescope them with the friction fit the ties would provide to hold the rods in place when you removed them from under the car.


I hope you have found your suspension nirvana... Lord knows the problems you've had on your to get journey there.

Enjoy!!