Sti 330S suspension development "project"

With the 08 STI, and again with the 09 STi 330S, I don't feel the same grip / handling etc. I had with my ( much modified ) Classic scooby.

I find it understeers on medium speed sweeping bends, ( worse if the DCCD is manual + locked or auto + used - as the rear pushes the front wide ) and there is little feel on medium or faster sweeping bends. Also a bit "wallowy". Generally for me does not inspire confidence to chuck it in.


I am quite familiar with suspension dynamics and tyres from previous cars and some motorsport but not an expert, and particularly not on the peculiarities of the hatch Sti.


Rather than go down the often suggested route of full alignment, bushes, springs and anti roll bars I decided to see just what can be done with the OEM set-up, and small changes to that.
I was aware of a tuner company who is ex formula, ex WRC etc. and is known for setting up suspension. Builds Time Attack cars, Can Am cars, club rallying etc. and off road stuff.
So While discussing with them the best settings, prodrive springs, whiteline poly bushes and a/r bars, it came up that a good look around and measurement would help decide the best way to go. It's not always simply add stiffer aftermarket parts.


So, I'll try and document what was done and how it worked.

Neil

The car was set up on a guaranteed flat surface.
General lifts / ramps apparently are very unlikely to be level, maybe a degree or two out, which will throw out some of the measurements.

The 330S had been 4 wheel aligned by the dealer as part of the PDI ... so I was told.


Front:
Toe OUT 0.5'
Camber 0.9 -ve left, 1.2 -ve right wheel
Caster 7 '
Setback - uneven ( can't recall figures, but a fair amount )

Rear :
Toe parallel
Camber 1.2 -ve left 1.4 -ve right wheel


There may be other figures i don't have.

Initially, the set back of the front wheels will be looked at, to get them in line.
This might be possible by loosening the subframe and suspension location points and jiggling the sub frame around to suit.

{Note : Subaru are renowned for deliberately doing this and other measures to induce understeer, e.g. toe out on front, more -ve camber on rears than front etc. }

If adjustment of the OEM parts does not do the trick, other means will need to be investigated, to adjust the wheel position. This may mean custom / fabricated parts to space out 1 wheel or pull back the other wheel. Offset bushes / mountings can be investigated.

The 4 wheels will be aligned against the centre line so all are equidistant. ( remember the tyre places who wind all the steering rack track adjustment onto one side .. they make the front wheels to move out of line with the rears... need to adjust equally on each side. )


As the caster at the front is above the expected specification for the hatch then available kits which add caster are not ideal. This situation does help the effectiveness of the camber settings though.


Also the roll centre / bump steer mods are less necessary in this case.
In any case the roll steer mod only really works / is needed when lowering the car on lowering springs, to maintain an appropriate angle for the links.

Once the basic chassis settings are in spec / optimised we can see what adjustment is available in the standard suspension - front camber bolts come as std, the rear has none and minimal other adjustments.

Aiming for more camber at the front than the rear, and some toe in at each end, again, more at front than rear.

{ Looks like dealer has done a simple "4 wheel alignment" and just set up the tracking, and even then it is poor although within the Subaru allowed specs! }


Aiming to dial in upto 2 degree -ve camber on the fronts ( possible tyre wear issue especially with the 245 tyres?? ) and around 1.2 degree on the rear. This may require the first aftermarket parts - camber adjustable bolts.
About 0.1 toe in front and rear, although as said less at rear than front.


Whiteline advertise an adjustable rear wishbone, but that is still not yet available due to development problems. That would have been a more elegant solution at the rear.

Some interesting parts from Whiteline... ( other manufacturers are available! )


Whiteline website and Subaru parts lists...
http://www.whiteline.com.au/search.php

Whiteline advice & explanations
http://www.whiteline.com.au/vehicle_alignment.php


Some nice parts...
http://www.whiteline.com.au/docs/bulletins/252%20-%20new%20Whiteline%20sway%20bar%20links.pdf

http://www.whiteline.com.au/docs/bulletins/249%20-%20subie%20new%20products.pdf

http://www.whiteline.com.au/docs/bulletins/176%20-%20KDT%20POSITIVE%20POWER%20KITS%20-%20WEB.pdf

Usefull a/r bar comparison chart...
http://www.whiteline.com.au/docs/bulletins/170-%20bars%20on%20cars.pdf

http://www.whiteline.com.au/docs/bulletins/161-%20rock%20sti%2008.pdf

http://www.whiteline.com.au/docs/bulletins/160-%20anti%20lift.pdf

http://www.whiteline.com.au/docs/bulletins/157%20-%202008%20impreza.pdf


At the moment adjustable wishbones are not available.

Looking ahead, once the general settings are sorted, test driven and tweaked for the driver, then options like lowered stiffer springs ( and alignment etc. reset ) and any other items needed to maintain the correct angles and alignment would be sourced.

Following that, stiffer anti roll bars ( probably rear only at the moment ) with polyurethane mounts and adjustable drop links would be next if needed.


At some stage, the rear bushes would be treated to the PU filling plugs as part of the positive traction and diff kits ( or full bushes as needed ) and any other areas requiring bushes would be dealt with.
I expect the bushes would come earlier after / during the original set up and before springs and a/r bars.

I need to reduce the ammount of negative camber on mine on the rears ive just wrecked a set of pirreli tyres -2.5deg on the rear mind you it did bloody corner well

Rob wrote:I need to reduce the ammount of negative camber on mine on the rears ive just wrecked a set of pirreli tyres -2.5deg on the rear mind you it did bloody corner well

Rob

You've got that much -ve camber due to the lowering of the car!
The body is lowered ( by lowering springs or lowering the spring pan on coil overs etc. ) and hence the chassis, and suspension mounting points are lowered. This alters the angle to the mounting points on the hub.
The lateral arms inner ( by diff) pickup point is lower so the arm is more horizontal and that "pushes" out the wheel hub, hence causing more -ve camber.

You could raise the car and reduce the camber - if you have access to camber gauges try 10mm or 20mm and check camber.

Or fit adjustable lateral arms (I had those on my classic ) although Hatch's are a bit different.

Or try a camber bolt in the top hub/damper mounting to push out the top of the wheel, or in bottom mounting to pull in the lower part of the wheel. Using both top and bottom camberbolts would give around 2-3 degrees of adjustment I believe.

Obviously check camber and tracking when changed!
Hope that helps?

Rob wrote:I need to reduce the ammount of negative camber on mine on the rears ive just wrecked a set of pirreli tyres -2.5deg on the rear mind you it did bloody corner well

Rob,
Whiteline do a set of bushes for the top wishbones that alters the camber as required, believe they're a pain to adjust.
http://www.whiteline.com.au/product_detail.php?part_number=KCA326

Powerflex also do bushes, which I believe are easier to adjust.
http://www.powerflex.co.uk/product-details/Rear+Upper+Arm+Inner+Front+Bush+ADJUSTABLE/1624.html
http://www.powerflex.co.uk/i/product_images/PFR69-511G-F.pdf

Paul.

The whiteline product shows bushes and an ovoid bolt to achieve the change in camber.

The lower of the Powerflex links shows bushes and a sleeve, the sleve does the same job as the offset bolts.

Both seem a pain to adjust, as are any camber bolts, but may be a way forward.

Here are the std spring rates.
Standard Springs FR 38 n/nm
Standard Springs RR 34 n/nm

Prodrive springs - apparently Prodrive don't know!! More likely won't say.
They are shorter, stiffer and progressive springs I believe...


The Jap Subaru parts range ( I think ) had these springs and rates : ( copied from another post! )
Not sure which springs these are 0 listed as STi springs :
ST20330ZR010 :: Front springs rated at 50N/mm, approximately 5kgf/mm (Lowers the vehicle approximately -15mm)
ST20330ZR020 :: Rear Springs rated at 40N/mm, approximately 4kgf/mm (Lowers the vehicle approximately -15mm)

Has anyone (Mark ? ) ordered any parts from the Japanese STi shop?

If so, what deliery time, any isues / problems, import taxes & carriage etc.

Thanks

Do all the Jap STi parts fit the UK car - I know engines, d/pipe etc. are different but how about the suspension parts - braces, springs etc.

Thanks

Still awaiting final price and work spec from the tuner, I know a couple of items are out of stock at Whiteline ( bump/roll steer kit ).

Looking like working with SuperPro with their current full car bush kit ( albeit developed for WRX ) and adding Whiteline parts when needed.

STi japan parts on order - the strut brace with the ball joint, and 2 under car STi chassis braces.

WHiteline parts arrived at garage, still waiting forthe sexy STi parts from Japan!

Hey vulnax, see you're in the same area as me. Where are you getting all this done if you don't mind me asking?

Not a problem.

It's Chevron Motorsport of Stafford.

Simon is the main man, does time attack cars and other racing types, alongside a usual car service place.

Hello

When you get it all fitted, give us a shout and we'll gladly do you a great deal on a full Hunter Aligment set up.

Glenn
Revolution

Hi Glenn, erm whats a Hunter Alignment setup?

I should have full alignment ( not coil overs / adj top mounts and rear adjustable links are not yet available ...? )kit front & rear and full 4 wheel alignment, with set back sorted, anti roll/bumpsteer, full PU bushed, etc.

Always open to option ...


Seems the STi braces are R205 parts!!

hunter alignment is 4 wheel alignment.

Hunter is probably the best alignment system in the world!!
here for more info:
http://www.revolution247.com/4-wheel-alignment-67441-0.html

uses 4 cameras rather than lazers to align any vehicle.

When you fitted it all and have it set up properly it will drive like a dream!

Sti braces are cool, but we do whiteline and Summit parts and they are spot on too.

Glenn

No progres as yet.

As I had been told that the R205 parts ( th rear diffuser ) is unlikely to still be available I checked on the STi ( ex R205 ) strut brace and 2 undercar support braces availability.
Seems they have not YET been ordered - they were coming via RCM apparently. BUT with the exchange rate to Yen changing they want yet another £75 on top of the quoted price. So they were stopped.

So I'll check out Japparts and Nungun as they state they have them in and for same price when I looked in Feb 10. Main difference is cost of delivery.


We were getting feature creep ... offered a set of new design Bilsteins, at "cost price" but not a lot of info on spec etc. I was reluctant to be a test bed for products I know nothing about, especially if asked to pay cost price and fitting labour.... so I rejected them!


Back to the original ideas at the top of this thread - set up to best factory specs, then lower springs and correct roll/bump steer, max -ve camber and fill voids in rear bushes, rear thicker a/r bar and braces.

Full set up.

Right, Disappointed at not getting my STi strut brace and both under car STi braces / subframe support, I ordered them from Nengun and Japanparts.

WIll be imported within about 2 weeks all being well, and well under what I was quoted for UK supply before they let me down and increased price.


Elsewhere on here I had mentioned a wah wah wah noise at 25 - 55 ish MPH from the front wheels / driveshaft / gearbox, in neutral or with clutch dipped. Subaru changed 2 wheel bearings to cure it, but no joy, louder now a month after the change.
Have to go back for yet more people to have a listen and let me know. My guess is still bent driveshaft ( maybe from the snow ?? ) or worryingly something in the gearbox - front diff???

I'll be back...

Hi Vulnax

We have had the items you want in stock since the beginning of this year....give Keith a call and he will sort you a good price out.
Thanks
Glenn
Revolution

STi front crossmember brace kit ( 4 bars and fitting kit )


STi “flexible” underbrace ( the single bar with rose joints on each end, adjustable ).


STi Flexible strut brace
These are some of the goodies I ordered from Japan - seems to be R205 bits / 20th anniversary!