Fuzz

what do you reckon.



Andy

DuncanG

Take it to PowerStation mate, they'll sort you out

Jolly Green Monster

iTrader: (4)

From watching the video Andy I think you could weld a bar to the springs and it would still do that.. damn quick!

Simon

Fuzz

@ Duncan.

So you don't think stopping it leaning so far on the suspension would help?

I presume just sticking a stiffer set up on the front would induce the understeer I've just got rid of??

I've already got a 22mm front ARB and a24mm rear so can't control body roll in that way.



Andy

DuncanG

Sorry about my silly wee joke, it was just too tempting I'll try and be more constructive.

Its easy to get into the mindset that to reduce understeer you need to stiffen the backend. But there comes a point where you've got 100% weight transfer at the back and it still seems to understeer. Your pic above is a good example of that. Obviously making the back stiffer wont help as its already lifting a wheel.

Although it doesn't seem right, stiffening the front will reduce understeer and increase grip by reducing the amount of camber change during roll. More static camber will help too.

When I saw that picture I wondered if you were still on the brakes as the front looks well down, but your brake lights are off so I guess your just off the brakes (duh, thats not too unusual approaching the apex). Yes it looks like your springs are too soft. I wonder too with that amount of dive and roll if your much harder on the outside front bumpstop that you might think - that will make the front push wide especially if there's a mid corner bump.

I had a look at your website and you've got some fabulous pics and videos there. The in-car videos at the sprint track are great. A quicker steering rack would help, you're working hard there. Are you still using the A539s, do you feel they grip well? On my 205 I used to run wider tyres on the front, I wonder if that would work well on an Impreza? A front Quaife (if you don't have one already) will make a huge difference. You don't notice them working except that it feels like your on rails.

So what setup are you running in terms of springrate and alignment?

Fuzz

Ohh long one cheers

Where do I start..

Alignment settings.
What you can't see on the quick printout I did is the 5.15 degrees of castor I now have with the noltec top mounts (on the front lol )



Note to anyone wishing to try those settings... CV joints are £205 quid each !! and take a listen to some of those videos on the tight bends and you might think twice!

Tyres are already changed fronm the A539's and now are wider too at 215 x 45 x 17
bit stickier too.



As for diffs I have a suretrac equipped six speed (STi Type UK box)
and standard UK 00MY rear and the springs are the ones you get in the DEP, Driver enhancement pack fitted by Prodrive.
Basically Eibach springs with bilstein (non ajustable) dampers, unsure of the rate though.


Andy

DuncanG

Thats a hell of a car. You've probably taken it to about the limit of a general purpose car. So the question is - for what application do you want to make it more specialsed and what are you prepared to sacrifice?

Some ideas to throw around -
Does an extra couple of degrees of camber really affect the UJs that much (its not something I've checked)? If the UJs will tolerate it this might work for the sprint tracks:
Add a second set of camber bolts on the front and with the top-mount camber set at min adjust for a good road camber (say 2deg) and zero (or minimal) toe. Then for track use set the top-mounts to max camber which will also give a very agressive toe-out which should help on the tight corners. For going home move the top-mounts back out. Maybe the full-swing will be too much but you get the idea..

The prodrive springs I would guess will be around 35N/mm (do you have spring tester at work?). There's plenty of scope for going stiffer from there. The options obviously depend on budget and whether you're keeping the struts. I expect you could get them revalved for stiffer springs, eg the Sti 'gymkana' springs at around 50N, or get a set custom made - its not that expensive. Maybe you can get a set of ASTs for endurance testing.

Don't Whiteline do 'racing' spec arbs now? It would be interesting to see what effect just a front arb upgrade would have.

That's me out of ideas, where's 911?

Fuzz

Cheers again Duncan,

If I adjust the top mount camber in either direction I will lose some / have to sacrifice some Castor by the way I fitted them.



I originally had 2.00 degs camber (with the top mounts in the same /current place for Japfest at Coombe this year, again the car never fully felt over steery but drifted fairly neutral with a hint of understeer still on the fastest sweeper before Avon rise (on full attack I can go from tight apex to the other side of the track in a fairly (?) controlled drift (not a tail out one, just a slide)
I have also spied the racing ARB's that whiteline do ane would be willing to try them if I got a decent trade price (still working on that )
Work are trying to push me towards the AST's nearly every time we do a classic, now although they are the very good, I personally want to stick with Bilsteins, typically double the price though, and the spring rates wouldn't be suitable anyway so there will go another couple of hundred quid on top of that. Hence why I'm still on eibachs....
No spring tester at work that I know of..

the car will be a pure track car from now on, will be driven too and from events, for now, until it gets so unforgivable that my teeth fall out anyway.
Sprints, circuits and hill climbs will be all it'll do. I'm not a 1/4 miler at all.
I have a little run around to get me to work and back. (512miles on £40 of derv aint too shabby )


Andy

DuncanG

I think you are too hardcore for the ASTs. I'd expect 60/50N springs would work well for you but the ASTs wont handle that (at least the ones I had didn't). Your billies should be rebuildable so they shouldnt be double the price - around £500 for revalve and custom springs at a guess. Still not cheap and its a bit of a hassle. Coilovers makes the spring selection a lot easier.

Top-mount / caster -
Use that top-mount setting as the sprint position then swing it out for road, in between for fast tracks. It looks like they'll give a good camber-range oriented the way they are even if its not abs max. It all depends how the change of toe feels on track. You'll need the extra camber bolts to get the camber up to around 4deg for sprint setting. Just an idea - it might work you might hate it.

911

Having met Fuss for the first time yesterday at PS I've just pick-up on this thread.
I have the very same condition but entering/passing through tighter bends.

I fixed the wheel lift initially by movimg the 22mm bar at the rear to softest but the car suffered in other ways and i went to middle position.
That was last year and 314 bhp.
Now the engine is a 'little' stronger, the car faster the condition is back!
I loose a lot of time on the hill climb due to loss of traction (stock Sti v3 trans)

I can't help but think much more radical work is needed to stop this condition.

Andy: Have you sent the pic to Whiteline direct and asked for advice?
At the rick of sounding stupid; do you think a quicker lap time would come if you entered less aggressivly and so allow you to pull out much harder with a more stable car attitude?

Just to amuse:


Graham.

Fuzz

that bloody picture again lol.

T-uk

my KW's run 60/40N and the car stays fairly flat with anything I can throw at it on F1's.

trying a car with 50/40 recently I was surprised by the front end roll and dive under braking compared to mine.

911

When i started out on my chassis everyone told me to keep the rear spring rate 80% of the front.
60/40 is a long way off that...maybe there is something here.(?)

Some other amusing pics:

Understeer 2 years ago at 50 mph


T-UK:

Can you get a wheel to lift at the rear?

Graham.

T-uk

I was told that in theory my rears needed to be higher but they seem work well.

on road tyres, the closest rear wheel lift was probably at elvington and that was on fuldas that I hated. I also had toyos but the car only did 2 or 3 runs due to a slipping clutch so never tried them.

I like the KW's and was even more impressed at the last knockhill track day. I was following a cusco(iirc) coilover scoob that was running slicks . he was hitting the kerbs and lifting the whole side of the car , touring car style which looked impressive but was actually slower than my car which just rode over the same kerbs. his hard suspension and slicks with stiff sidewalls just looked too firm for using that amount of knockhill kerb.

I had always thought of them more as a fast road spec as they do not hop around like the jap brands and are not really that crashy on rougher roads. not sure how they will stand up long term though for track abuse. not really sure if coilovers around this sort of money will last.

911

As Fuzz knows, my rear AVO's were shot when stripped at PowerStation on friday yet I couldn't really tell in the car...!
The rumble strips on many hill climb corners are really evil paving slabs set at an angle.
My Sti has ridden these more than a few times and the car jolted violently each time. This was on 300Fr and 240 rear (80% rule)
Car ran really well on the road though, especially B and A roads.

The AST's seem much smoother altogether. It will be very interesting to see (feel) the effect at Loton Park soon.

In hill climb circles there is a genius called Alan Stanisthorp who will examine and advise on any chassis to optimise the car for road/track.
He has written several books on the subject and this may be worth looking into for roll stiffness/compliance.

Fuzz: What setting is the rear bar on? (when the pic was taken)

Graham.

Erik

I run with LEDA 320/275lbs and OE sway bars with MRT links+bushes. If have something like Noble ( no sway bars) it is a question of spring
Otherway your swaybar is too stiff and pulls your wheel up. For choise is hard spings and dampers with not so hard sway bars or softer spings with hard dampers ( to cope extra load from swaybar on corner ) something like EVO. Making all thing hard is not best idea.

911

If the bars are weaker then the suspensin will not be lifted, but if the strut cannot extend (droop) far enough the body roll will lift the wheel!

I'm with Erik, but finding a 'stiffness/compliance' is the task (correct for all conditions)

Graham.

Erik

You just need team of mechanics, or one car for cruising, one for track, one for fast road, one for wet, one for snow ...
Or buy an Citroen wih hydroactive suspension
I get very good rear response with this one: http://www.ravensblade-impreza.com/m.../subframe.html
Just two little bolts and so much defference.

911

Yes, essential for all Impreza's!
Graham.

chrome

Couldn't find the video Andy; would you care to PM me a link- as I have a horrible feeling that I'm going to recognise 'that' sound you mention above

911: Ooh a cheap mod - might be up for some of that.. shall have to call my friendly local WL dealer (Scoobyclinic!)

911

And they can be installed without removing the wheels or jacking the car up!
Graham.

Fuzz

Chrome. you should find some on here.

www.ashlyn.plus.com/video



I bet Powerstations prices are better.

Andy

chrome

um.
er- which one for 'that' sound??
On the haynes vids all i hear is tyres squealing, and the sneezy BOV

Will ring PS tomorrow

jasonius

iTrader: (1)

In what way do these bolts help..?

Jason

911

1
Tie down the rear subframe so aligning the suspension arms laterally in the car shell
2
Tie down the subframe at the diff mountings which, with the stiffer cradle mounts and diff mounts, stop the rear jumping about on very hard standing starts.

Great mod for cars stressed to extreme levels.

Graham.