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Just seen a set of springs for a '95 9000 Aero on e-bay and wondered if they would offer any noticeable improvement for my 96 9000 CS Eco/Lpt (newbie apologies, but what is the correct terminology for my motor? 9000 CSE, 9000CS, 9000CS eco...)

Thanks,

Pete
 

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The Aero springs are one cm lower than stock springs for your car. I know people here in Sweden that fitted those and were disapointed because the different isn't that big


If you're after more dramatic change you should go for the H+R, Eibach or eqvivalent springs instead. Depending on how old your car is you might have to change shocks aswell since they tend to start leaking when they start working in another position...
 

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A change in spring height changes the travel of your suspension and naturally your shocks will travel along this shortened distance(which also means you've got the same forces to dampen but over a shorter distance). This is why performance shocks are generally beefier - they control the same force created by the car as it travels, but over a much shorter distance and why standard shocks just don't cut it when you change your ride height. Thats my casual observation anyway..
 

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When I installed lower springs on my 9000 it had only 39k on the clock and had stock shocks. It worked fine until I changed to Bilstein shocks at 64k so it's not certain that the shocks won't work.
 

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At the risk of seeming to be a pedant (surely not!), it's not the fact that the springs are shorter that requires more damping, but if they are stiffer. Most shorter springs are stiffer (otherwise you'd bottom out a lot!), however whether the Aero springs are different enough from the standard springs to require an increase in damping is another matter.
 

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I suppose if you are going to do it right then you need to make sure the damping rates are the same as the aero's too otherwise I doubt you'll really enjoy the benefit. That's not to say that the aero damping rates are different from standard (as i dont know) - but I would have thought that those aeros dampers they were a bit stiffer.
 

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Your dampers are designed to control rebound, if your springs are shorter your dampers need to decelerate your car body's movement over a shorter distance (which is why the size of the damper valve will be larger in a proper sports damper, thereby displacing the same volume of oil over the shorter travel as a normal damper over longer suspension travel). The stiffness and length of your springs should be such that they do not result in bottoming out , your dampers are not a compensation for cut springs that are not rated to work under a reduced range of travel.
Springs and shocks have different jobs to do.
 

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surely the dampers are matched to the springs stiffness not length. If the shorter springs allow too much body movement (assuming the same stiffness as standard) then you need firmer springs with dampers to match.

Not sure I understand your statement - the first para says you'll need firmer dampers for shorter springs and the 2nd says firmer dampers are not a compensation for shorter springs. - Maybe I'm confusing cut with cut+stiffened.
 

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i think we may have a mountain and mole hill situation here.

all components have certain tolerances. i can say, with a fair amount of certainty, that a 1cm drop in any car barring a ferrari or spyker will work quite well with the original shocks or struts.

yes, if you drop a car a substantial amount, 2-5cm or more, you will need to get shocks that are valved differently to properly dampen over a shorter distance. but i really don't think 1cm will make a bit of difference aside from lowering the car's overall center of gravity.

also, i don't think anyone was condoning cutting springs to make them lower. heaven forbid! but replacing them with properly calibrated sport springs that offer a stiffer ride and 1cm drop sounds like a good economical solution for slightly better handling.

correct?
 

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I think we all furiously agree that dampers and shocks need to be properly rated in respect to one another and that a 1cm drop in suspension travel isn't going to cause any issues. In terms of my focus on suspension travel instead of spring stiffness, it is fair to say that in a properly engineered set of springs that travel and stiffness are both relative parameters of the spring design (ie. larger gauge steel is used in a shorter spring in order to suspend the car over its shorter ride height) of course the car would bottom out otherwise, or if the shocks are not suited to the lower ride height and therefore reduced suspension travel, you'll get rebound in your suspension causing your car to bounce along in an uncontrolled way. Good to see passionate debate over this serious topic
.
 

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And just to throw more cats amongst the pigeons, whilst agreeing with all the theory, I offer this snippet for thought...

Consider a 1500kg 9000 unladen, with an approximately 60/40 weight distribution front/rear. So that's 900kg on the front, 600kg on the rear.

Then consider it fully laden at 1900kg, the majority of which will be biased towards the rear say an extra 150kg on the front, 250kg on the rear. We're looking at a change in loading on the rear springs and shocks of just over 40%!

The point of this illustration is to support the fact that because shock absorbers are designed to work adequately over such a wide loading, it is acceptable, subject to limits of shock travel, to use shorter/stiffer springs with standard shocks as you will rarely have more than a 25% change in spring stiffness from stock.
 

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Originally posted by Skiddins:
[qb]I think someone needs to phone a dealer and ask if the shocks they could supply would be the same for the Aero's and the other models![/qb][/b]
No, they're not. The Aero dampers were different front and rear from the standard ones. However, the same items may have been used on the "sport chassis" option that was available on the 9000. The rear dampers, at least, have a bronze-painted ring around the bottom where the standard ones have a red ring (or perhaps none at all). The label on the front struts carry a different number, but I can't remember the numbers offhand. The Aero front strut is physically larger in diameter than the standard strut, as is the piston rod.
 

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Aero dampers are indeed different from standard turbo ones, colour coded brown rather than red and the front struts have 25mm damper rods rather than 22mm ones. Unfortunately they are no longer available from Saab, as of April when I gave up trying, and quoting the part number to Sachs gets you referred back to Saab

I ran my Aero for 9 months on standard turbo dampers and found them unable to cope with the stiffer Aero springs...luckily a set of Bilsteins saved the day
 
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