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Running Tein S techs on my hawk sti for over a year now on standard shocks. Car looks much better and after the geometry was done handles miles better than before.
The cost for the one off kit is £263 + vat (£315.60) and courier delivery £11.25 + vat (£13.50). The kits comes with the crucial replacement front bump stops, fitting instructions for the bump stops and revised static geometry settings. It takes around 20 working days to make a set. They are powder coated in silver with a high zinc base powder coat. Please see the attached picture. The springs lower the car by approximately 35mm at the front and 15mm at the rear. The kits make a significant difference to the way an STi drives. There is more body control with reduced roll and pitch. The initial understeer is reduced and the steering is more responsive. An added bonus is the ride is calmer with the 'STI bobbing' being massively reduced.
To be honest, I can't see what else you are getting for that HUGE price of the PCA kit over just normal lowering springs.
When you lower the car with any springs you should always do a full geometry check and adjust for camber, tow and caster. This will probably cost you close to £100 for the geo setup by itself so be warned. BUT it is a must otherwise you will tear tyres and the car will probably handle worse than before you started.
I fitted Tein S Tech springs myself, took a couple of hours at most and had the full geo setup done a quicksh1t (who have the most advanced machine in the area but the most stupid staff.... I helped them set the car up myself). Handling and looks are FAR increased over standard. I have run this setup for 7 years now without fault on my every day car.
Also, 15mm drop on the rear doesn't seem like enough for me to compensate for the 35mm front drop on the PCA kit?
Last edited by BrownPantsRacing; Jun 29, 2015 at 10:43 AM.
Hmmm OK, it does seem expensive but it comes with bump stops. How much are these separately and are they a vital part to replace when fitting new springs?
I'm very un-technically minded by cars and modifying, I just usually pay for people to do it! I only mentioned bump stops because I was told it's good to do it at the same time and I don't want to lower the car and not do it if it's required.
Plus PCA mentioned bump stops which made me think its worth doing. Plus if the strut is out anyway, might as well just do it surely?
Yeah, 4x springs which need to be made to order and bump stops. I quoted up above a few posts the email which came to me. Tein seem a lot easier, cheaper and give a better drop.
A, relatively, higher rear ride height, moves the roll centre rearward, increasing rear roll resistance.
That, in turn, makes the front end roll more - helping turn-in response and reducing understeer, without the use of stiffer bars.
You want the smallest bars possible, on a road car, to avoid 'roll-rock'.
Roll-rock:
If the spring rate is relatively low and the sta bar is too stiff, a suspension movement, initially, occurring on only one side of the vehicle, will be transmitted to the other side, inducing an unsettling 'roll-rock' motion.
Bump stops are critical to handling balance, especially on a lowered suspension.
I didn't realise the bump stops would be so critical? Is the impreza really riding on the front bumps stops that much when pushed? That doesn't sound right to me. I'd want the springs doing the work rather than the rubber bushes.
So I presume the updated ones are shorter or of a different compound?
I didn't realise the bump stops would be so critical? Is the impreza really riding on the front bumps stops that much when pushed? That doesn't sound right to me. I'd want the springs doing the work rather than the rubber bushes.
So I presume the updated ones are shorter or of a different compound?
I know odd isn't it.
For instance: The pca front stops, for inverted dampers, are 50mm long, but the first 10mm is a very soft nose, to give a progressive engagement.
The oem bump stops are a form of pitch control. Which is why the bobbing sensation occurs - spring then bump stop then spring, and so on.
If you have soft springs for comfort, then a progressive bump stop can, under cornering, assist the spring to feel stiffer - very common solution.
If you lower, without considering the bump stops, you'll be on them permanently.
Lowering too far, causes the roll centre to become so low, that the car rolls more. The roll centre lowers 2x the ride height reduction.
HTH
I know odd isn't it.
For instance: The pca front stops, for inverted dampers, are 50mm long, but the first 10mm is a very soft nose, to give a progressive engagement.
The oem bump stops are a form of pitch control. Which is why the bobbing sensation occurs - spring then bump stop then spring, and so on.
If you have soft springs for comfort, then a progressive bump stop can, under cornering, assist the spring to feel stiffer - very common solution.
If you lower, without considering the bump stops, you'll be on them permanently.
Lowering too far, causes the roll centre to become so low, that the car rolls more. The roll centre lowers 2x the ride height reduction.
HTH
Very interesting indeed. So as standard the impreza has very little front end suspension travel before the bump stops come into play?
I have to say, mine is lowered with the Tein S Tech springs which is probably as low as you want to go with lowering springs before going coilovers which eliminates the bump stop issues anyhow. I have never noticed any bounce issues at all on mine. Certainly doesn't ride like it's on the bump stops. I may have to have a look and measure to see where they are and what travel I have left.
Peter Cambridge was, for 12 years, Prodrive's road suspension and handling designer.
I think he did the Prodrive Aston Martin Vantage and RX8's , as well.
ok
