Project 92 SC - Suspension

 
Things I was looking for when considering suspension choices:

 Very aggressive spring rate (unlikely to be streetable)
 Struts that offered damping to properly match the spring rate
 Some way to adjust camber when going back-and-forth between road course & dragstrip

When it comes to suspension, there aren't a lot of aftermarket choices for Saturn.  There is a good variety of springs out there, but many people are forced to run them with either stock struts or the slightly stiffer struts offered by KYB.  Carrera made 2 types of struts for a while, but they've since been discontinued.  I knew it was a longshot trying to locate anyone selling a set of Carreras, but SPS put me in contact with someone who was selling an adjustable ride height coilover setup.  Sweet.  Now at least I'm halfway there.

NOTE: With the availability of a lot of cheap 'coilover kits' on the web - it's worth mentioning that these are the real thing.  The cheap kits offer adjustable lower spring perches and a set of springs which most people install on their stock struts.  Rarely is the spring rate properly matched to the strut's damping, and while the owner now enjoys 'stiff & low', the car's ride suffers greatly and performance will not be optimum.

Click the thumbnails below to view a larger-sized image.
  

Carrera struts

  
Here's all the pieces of the Carrera system as SPS used to sell it.  The stock top mount isn't shown in the picture, and the ring that the threaded collar sits on has already been welded to the housing.
  

Strut cartridges

  
The Carrera cartridge body (white in photo) is slightly shorter than the Koni race cartridge which offers rebound adjustability (red in photo, Koni part # 8610-1149).
  

Too long

  
The Koni will fit in the Carrera rear strut housings, but not in the shorter front housing (as shown at left).  Some machining will be in order to make the front housings slightly longer.
  

Top caps

  
The original top cap is the one on the right.  The easiest way to try to get the Koni cartridge to fit was to make a new cap that was slightly longer (shown on the left). Unfortunately, that didn't work.
  

No taper

  
The top of the Carrera cartridge is tapered to allow the threaded part of the cap to screw down past it.  The body of the Koni (on the left) where it enters the housing is not tapered.
  

Modified housings

  
The solution that did work required cutting the housings, and welding on a slightly longer threaded tube along with a new ring for the threaded spring collar to rest on.  A tip: you better trust your machine shop!
  

Tight fit

  
Here's a shot of a test fit on the front (stock wheels & tires, about 1 degree negative camber, lowered about 2 inches, no wheel spacers yet).  Damn, that's a tight fit.
  

Front housing coated

  
After the modifications to the front housing tubes and all the test fitting, the housings were all sandblasted and powdercoated an aluminum color.
  

Carrera springs

  
When SPS used to sell this coilover setup, they included springs with a rate of 225 & 250 in lbs.  I decided to go a bit stiffer, and chose 300 & 325 in lbs.  Carrera springs are chrome plated, and really look nice.
  

Final assembly

  
Now that I had all the pieces and all the modification work was all done (details are below), it was time for final assembly.  You can see a very large, hi-res photo HERE.
  

Front mount

  
I'll be using the stock upper strut mounts to start with.
  

Assembly with knuckle and hub

  
How do you remove your suspension while preserving your alignment?  Take the whole knuckle and hub with it.
  

Front mount in car

  
Here's a shot of how the Koni cartridge is adjusted - just turn the pin.
  
  
When this Carrera coilover system was available, it was sold as a bolt-on modification.  It is anything but bolt-on, requiring a good amount of modifications and work to make it all fit.  Here's some of the stuff that was required:

The stock front upper mounts needed to have about 2 mm of rubber grinded/sliced off the bottom.  The washer which sits on the cartridge rod shoulder (and keeps it from punching the top mount metal sleeve and rubber right through the hood) needed to fit without having the washer contact the top spring cup.  This was so that the cup could rest on the mount's plastic bearing surface and rotate without contacting the washer.
Small pieces of pipe or washers were needed to shim the cartridge inside the housing so that the body nut cinched it down properly.
The bumpstops which come with the cartridges need to be cut down in size.
The brackets on the bottom of the housings required filing & grinding before it would fit over the stock knuckles.
The rings which support the threaded sleeve needed to be welded to the housing.
The housing's lower bracket holes needed to be grinded and made more oval, to allow more of a camber adjustment range.
Front and rear hub spacers were required to move the rim/tire away from the strut body and allow for a good range of camber adjustment.
Longer lugs were required in the front hubs due to the wheel spacers, otherwise the lugnuts would not have much of the existing lugs to grip.

And, because I chose to go with the Koni single-adjustable cartridges:

The front housings need to be made longer to accomodate the length of the Koni cartridges.
The metal sleeve in the top mounts needed to be reamed out to accept the larger diameter shaft on the Koni cartridges.

Observations

Surprisingly, the assembled coilovers appear to weigh about the same as the stock struts & springs.
Wheel selection is extremely important.  Diameter, width, and offset all have to be taken into account.   It would be very easy to install coilovers and have the tire and edge of the wheel come in contact with the threaded collar or larger-than-stock diameter of the strut housing.
With most wheels, it would be nearly impossible to have any amount of negative camber and be able to thread the lower spring perch down below the level of the top of the tire.  In fact, even with the carefully-selected 15" Konig Helium wheels I chose for this car and a set of wheel spacers, I cannot set the front end to more than a 2" drop.  If I want to set ride height lower than that, the top of the wheel must be tilted away from the car to create clearance for the spring perch now between it and the strut body.  At that point, I'm stuck with zero camber - and we all know that just won't do on a road course.  Using wheel spacers thicker than 5mm is an option, but doing this is sure to put more load on the wheel bearings and affect their longevity (which I'd prefer not to do unless absolutely necessary).  So, this ride-height limitation is fine with me, and I don't foresee need to lower the car more than 2 inches.
The length of the front housings is shorter than the rears.  Because of this, there is less travel in the front suspension before it 'bottoms' and the bumpstop becomes the suspension.  Adding about a half-inch of length onto the fronts to fit the Koni cartridges reduced travel even more.  At a ride height of 1.5" less than stock, the fronts have about 3" of jounce travel before the car will contact the bumpstops.  This is not much.  It's up to the damping of the Konis and the rate I chose for the Carrera springs at this point - fingers are crossed.
In talking to Team scR (thanks tons, James), I've learned that the rubber in stock top strut mounts does not work well with high-rate springs.  If the suspension is way stiff, the rubber gets severely pounded and deflects more than it normally would - to the point where it adversely (and unpredictably) affects the handling of the car.  The spring rates that I chose (300 in lbs & 325 in lbs) are probably at the top of the range that can be run with good results on the stock top mounts.  Camber plates and/or mounts that incorporate a spherical bearing and remove the compliance of the rubber will need to be considered if I choose to go with even higher rate springs in the future.  (And a special note:  With the cheaper coilover 'kits' people buy and install on stock struts and stock top mounts, people most often receive springs with rates significantly higher than this.)
Raising the ride height by threading the lower spring perch upward (which is very easy) should decrease the amount of negative camber.  For the dragstrip, this should increase the tire's contact patch in a straight line.  But, as I've seen so far in my garage, adjusting ride height also messes with the toe (think about the steering linkage rearward of the front wheels...).   If an alignment is done with the car at a 1.5" drop, increasing ride height from that point will cause the front wheels to toe out.  This is very easy to notice with ride height modifications even as the car sits in the garage.  Its too early to tell if this difference will be significant enough to worry about - when I get in a few quarter mile runs, I'll be sure to report back here.
If you're looking for springs and coilover parts, a great source is Speedway Motors.  And Shox.com ended up being the cheapest for the Koni cartridges.  Both also had extremely low shipping charges and the parts arrived in just a few days.

Update - 10/2002

I took the car to my local Saturn for an alignment.  I was looking for -2.5 degrees front, and -2.25 degrees negative camber rear.  After the front camber was set, I was very happy that there was a good amount of room (around 1/4") between the backside of the front tire/rim and the outside of the lower spring perch.  Unfortunately though, once the front camber was set it was not possible to set the front toe (possibly due to their alignment rack?)  Since the tops of the wheels were leaning inward, the beams attached to each wheel which normally point at each other were now crossing in front of the car and pointing down - to the point where the machine no longer picked them up to give a reading.  We eventually did find a way to approximate the toe settings though.

Until now, I had thought that I would be able to raise the ride height of the vehicle in order to decrease the amount of negative camber (for the dragstrip, mainly).  When trying this while the car was on the alignment rack, it showed that raising the car significantly did not really affect the camber.  Bummer - I guess I'll just have to work on getting some camber plates to get that adjustability.   We also saw that varying the ride height did have a much greater affect on front toe.

6/2003 - Carrera Custom now offers a wide variety of suspension solutions for Saturn cars, including a lot of what you see on this page.

Update - Due to a number of Saturn owners having extreme difficulty receiving the parts that they've ordered from Carrera Custom, I would personally not recommend doing business with them.  This is unfortunate, since there are very few sources for a Saturn high-performance suspension system these days.  :(

11/2007 - Dave at Team321 has indicated that he offers custom-manufactured strut housings for Saturn.  Visit his site here.

12/2008 - I've received an e-mail from the Agility Corporation.  They also make a trick coilover setup for S-Series Saturns, and you can check out their site here.
 

  
  
I realize that most of what is on this page tells about all the parts and putting them together.  If you really want to know how they will affect the handling of the car, here is an excellent technical article.  The second half will be of most interest.

 

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