bugged Outback

[sheppo9]

When you fitted the quick rack, did you need to use the Impreza or Outback rack ends and tie rod ends?
Still got the Bugeye rack?

When you took out all the lifting spacers etc,what did you do about the steering uni? Did the Bugeye or V6 uni work?

[vaccine]

I used the bugeye steering knuckle when I used the bugeye rack. The rackend was fine thread where as the outback one was course and not useable. Now I have quickrack from a gc8 which uses a course end so I just used the outack stock steering knuckle. Because the 25mm outback chassis kit was removed I had to get machine back the flat part of the end of the steering column where the bolt locates. Nothing 5 minutes work with the little grinder and a file didn't fix. As I have a whiteline RCK I used the rack end fit, they are a multiple fit for most dubarus. Yes I still have the sti rack and knuckle, and yes they are for sale. Shoot us a PM if your I interested.

[vaccine]

Small Update:

Spend Australia day around at my mate Bazza's aking a stailless CAI.
Throttle body is slightly bigger than 3", so 3" was the choice.
Stainless joint around the corner supplied the 304 for under $100.
Outback is MAP based from factory, so no MAF.
A few hours later.







But dyno say the wagon revs harder and pulls better.
The intake is also now ALOT louder than the exhaust.
Puts a quad weber setup to shame over 4K

I have not yet logged the intake temps, as initially this was the reason for the whole thing.
The stock intake setup would deliver a 30+ intake temp on a 18 degree day. More on a 36.
Depending, i might heat wrap the intake and used heat reflective tape over everything.

[MH3.0R]

Maaate, nice job on the Outback! Looks more like you are trying to join the Liberty Team Wagon fan club

Also hear from another source that you are thinking about a twin turbo mod. Any truth in that rumour?

[vaccine]

i had a couple of td04's sitting on the shelf. Was going to, but way too much effort in the plumbling.
back to 1st plan of the GT3040 sitting at home with a 1.06 v-band. east/west over gearbox.
that on with low boost, like 11psi and see how she goes. easy 200+.

though nothing will be happening till i can finish reverse engineering my ECU so i can flash.
can log all the sensors, just gotta find all the fuel/timing etc table now.

[vaccine]

Suspension update:

After racing a winton about 3 weeks back, i was bitterly dissapointed in the turn-in of my wagon. After doing some research it appears that my roll-centres are alittle wrong. Front looks like it is lower than the rear. Creating understeer into corners and oversteer going out. What i initally though was simply because of the bbugSTi track in the front turned out to be a combo also with McPherson front and multi-link rear suspension. So my solution was to either lift the front rider height or lower the rear. Or alternately go back to the stock wheel track. i opted to remove the bugSTi control arms and shafts, and fitted some gc8 alloy control arms and RA shafts in the front. By doing reduces the front wheel track by 20mm. making the front track 1470mm and the rear 1490mm. Doing so induces more oversteer and a general tendacy to help turnin at the possible expence of the rear tyres loosing traction.

i also rotated my Tein tops to point in for camber and back for castor. By pointing the tops in increase the SAI slightly by 1-2 degree maybe, but it also lifts the roll-centre in the process. Castor will be increase by going back, and with the 16mm of alloy plate i have installed between the alloy arm and anti-lif kit locator should hope fully net me 8+ degree of castor. which should really help with the slight increase in SAI. Combined with the narrower wheel track and short control arms, this also lifts the front roll centre even more.. should make the roll axis hopfully level or a little up. Waiting for some forulas to crunch the numbers on the roll-centres and actually work out where they are.

I haven't yet played with the ride rights, but may lower the rear slightly to same front and rear or maybe 5mm lower. Even in the wet on the way home, with bald sem-slicks, the wagon seemed to turn-in majorly different. Will have to wait and see how she goes at calder this weekend. Needless to say, she has put a huge big grin back on my face.

[vaccine]

Well i managed a 1:14.35 @ Calder Park. Was on the arse of a stripped/caged BMW second half on last session but car couldnt get there.
After speaking with some suspension guru's i have a few changes to make. I first need the fit the 22mm swaybar i have, which will give alot better mid-corner grip, where the previous stock 20mm has a tendancy to push and fall over in the mid-corner. Note that is with a 24mm rear swaybbar, so if you have a 22on the rear you want a 20mm front. The rear ride height is too high, which results in not enough roll as the Roll-centre is too close to the Centre of Gravety which makes the Moment arm to small giving no roll. i will also have to narrow the wheel track 10mm with the camber i have to clear the guaards.

The big one i need to work out is the Motion Ratio for the rear suspension geometry. The change was to go for a 30% stiffer spring in the rear to the front. I am currently running 6kg front springs, and 7kg rear springs. In pounds that equates to 335lb in the front, and 391lb in the rear. I was advised to go around the 500lb mark, or a 9kg rear spring. This will then help keep a better balance for turn-in and ride quality on bumps and corners in the rear.

Anyone interested in what the Motion Ratio is:
http://eaglewoman.rscsites.org/cobra/tw ... ratio2.htm

Time to get the lazer measurer out!

[teK--]

Dang I have not taken notice of this thread until now. V nice job on the suspension I love all the R&D you are doing and great notes too. Have you considered that the roll center at the front is so low because you have dropped the ride height so much from stock Outback?

Do the GC8 front control arms compensate for this, or would you be better off fitting a roll center correction kit?

IMHO inducing oversteer to mask an understeer problem is not the way to go as overall you would have less grip. Better to correct the problem at the front which will increase grip at the front instead, leading to more grip for the car overall.

[vaccine]

The GenIII front end geometery is identical to the GC8 impreza. I compared my stock steel arms to the gc8 alloy and they are identical. DMS, Prodrive, MSR and everyone else recomends a 330mm centre to arch on the wrx. Ground to sill measurement and wheel arch measurements are the same also funny enought. Which tells me that the roll centre in the front is fine, as confimed by MSR. He was saying the rear RC is to close the Cog, which means no roll, it needs lowering. But as the springs are too soft, this will induce more understeer. I need to increase the rear springs to get the balance of the car right, then lower the rear suspension to so the RC moves futher away from the CoG. Increasing the Moment arm which will help roll as there will be more weight over CoG. Which then the swaybar combo of 22mm front and 24mm rear i have will help fix the extra roll from the Moment arm increase.

I am not covering up my understeer with oversteer. the two are opposites in vehicle dynamics.
What i am trying to do is get the right combination of parts and aligmnent to get the car to oversteer on the edge of traction.

Ride height will dictate CoG and RC distance. (rear higher will create oversteer, rear lower = understeer)
Springs for ride quality and car stability or balance
Swaybar to control roll.

[vaccine]

Got to playing with the suspension on the weekend.
Working out the Motio Ratio's for the front and for the rear.

To work it out you measure the distance from springs seat top and bottom, and compare that to the wheel contact patch moment. ie 330mm centre to arch, measure 30mm below and above the contact patch, 60mm total. I removing the spring in the front and then measuring the difference in spring compression to contact patch moment. for 60mm in travel for the wheel the spring moved 55mm. This means a Motio Ratio of roughtly 0.84. Multiply that by your spring rate and you get your actual spring rate at the wheel or Wheel Rate. In my case i run 335lb(6kg) front springs, which multiplied by the Motion Ratio = 281 lb (5kg). Same for the rear and it was 0.61 Motion Ratio. Multiply that by 391(7kg) springs and I got 240lb(4.3kg rear).

You can see, because of the multi-link system the effect spring rate is reduced a lot compared to the McPherson Strut setup. After contacting some people very notable for their suspension knowledge, my thoughts were confimed. You need a bigger spring rate for the rear of the subaru’s that run the multi-link system.. So what Tein are doing is unresearched and just slapped together. Doesn’t seem as though they have looked into the different suspension setups. To maintain the same handling characteristics as the earlier Gen1+2 Liberties and pre 2007 Imprezzas handling you need to run a stiffer rear spring to the front, or you will induce more understeer and sloppy rear handling.

I am currently running 6kg fronts, and 7kg rear Jap Tein Flex. They came standard as 6kg front and rear. I replaced the rears with some 7kgs, but i am about to upgrade to the 450lb(8kg) rear springs and check the handling. Might go 500lb(9kg)’s yet.

Another thing I need to calculate is the swaybar spring-rate effect. Ie the amount of extra spring-rate the swaybar makes while cornering.. The swaybar has a static amount of sping-rate, that is then reduced as it also has a motion ratio that applys a % total to the wheel rate. Selby/Whiteline have on their web-site and % difference in stiffness, going from the 14mm stock rear to the 24mm has had a 600% + more stiffness, but its really just an arbitrary number. I have a calculator to measure the swaybar effects, just have to get back home tonight to work it all out.

[teK--]

Nice work with the calculations. So there is about 20% higher motion ratio at the front than the back am I reading correct?

I wonder if this f/r distribution is intentionally related to the weight distribution for the car, in which case if wanting to change beyond the factory f/r wheel rates then perhaps go up to 9kg rear springs like you're suggesting.

I am currently running 4.3kg/mm front and 6.6kg/mm rear springs with 20mm front and 21mm rear bar, am very happy with the balance that this gives. Since you are running 6kg front and 7kg rear I have a feeling that mine is (relatively) more oversteer biased than yours. This is notwithstanding that you are running a 22/24mm f/r bar.

Agreed re swaybar % being arbitrary all the figures quoted in sales literature really just go by the assumption of bar thickness in a fixed table of conversion values to work out the % increase. I doubt that the swaybars are dynoed.

Are you using your 22/24mm setup on the street, and is it manageable?

Look forward to seeing how you go with the 8kg rear springs you will pretty much end up with a similar balance to mine. May I suggest using Swift springs in your coilovers if you haven't bought the TEIN springs yet. Check out this post to see why: http://www.northamericanmotoring.com/fo ... ynoed.html

[sheppo9]

I'll buy your higher rate springs (7kg or 8kg) off you when you settle for what you want.

[vaccine]

you will probably find that for the standard rear lib setup that the Motion Ratio is slightly reduced.
I have 15mm longer control arms, so that raises the number slightly.

Jim what made you go for such spring rates? so 7kg front, and 11kg rear?
Give us a buzz, need a ride to compare.
0408 536 585

[teK--]

I am currently running 4.3kg/mm front and 6.6kg/mm rear springs with 20mm front and 21mm rear bar...

[vaccine]

rofl..
thought you had worked out yours through Motion Ratio numbers.
As mine are 4.3kg front after conversion.

where did you source your springs?