Daz

 

Graham
what Curtis came as well with the other mods (read your mods!)?
That would weigh the car down a bit!!

You've got virtually the same set up except you have AST suspension and a front lower strut brace (I have a top front strut brace)

If I keep the car I am still tempted by AST - I might just use the car for essentially track use so would opt for higher spring ratings.

Others
ALK was one of the best mods I did to my sti5........ sorted out understeer immediately but it did need the alignment doing afterwards

 

911 - Just out of interest, what are those spring rates in lb/in?

 

Hi,

I just thought I would my 2 pence in.

The perception of handling, grip and traction is a very personal experience and is influenced by various things. As we are all aware, suspension set-up is always a compromise. For day to day use on our Queen's highways our cars need to able to deal with a lot of varying conditions like road surface, weather and driver input. So my idea for these type of cars is that they need to perform satisfactory most of the time.
I normally find that making all the suspension parts do the job that they were designed for the best way forward although there will be a slight overlap of jobs done by the springs, bars and shocks. What we are trying to do is to get the maximum grip and traction from the tyres with an acceptable handling balance. Starting with tyres. These black things keep us attached to the road, or more accurately, keep us from venturing into the scenery. It stands to reason that the grip and traction generated by these tyres have a direct influence on the other parts of the suspension. E.g., more grip from the tyres will require more roll resistance in the car.
So having chosen the tyres, the springs will be next. The springs are there to hold the car up. In order for the car to have decent grip and traction on a variety of surfaces, it will need to have decent compliance. The idea of controling roll with springs is very outdated in my opinion. Spring rates that are to high will result in a car that is unconfortable and create less grip and traction over bumpy surfaces including longer braking distances. Shocks are there to control the springs with a slight overlap where the shock will hold the car up (through low speed bump damping) by reducing the initial acceleration of the suspension during turn-in and braking. Too much rebound damping normally results in a very unconfortable ride quality (the shocks you feel through your back and bum are normally signs of excess rebound damping) and the car 'holding on to it's wheels' on bumpy surfaces.
The anti-roll bars are there to control the roll. These are the easiest way to increase grip and change handling characteristics. Again we are looking for a set-up that is acceptable 90% of the time. If the bars are used to change the handling, f.i. reduce understeer, the first thing that needs to be looked at is what type of understeer the car suffers from. Is the car rolling into understeer, is it just washing out or does it push on under power in the direction that the rear wheels are pointing?
If the car rolls into understeer, the front bar rate will need to be increased. This will aid traction at the rear wheels as well. If the front bar rate gets to high, the car will start washing out at the front. If the car pushes on under power in the direction that the rear wheels are pointing, I would assume that there is not enough inside rear wheel slip. Increasing the rear bar rate to increase this will normally allow the car to regain front end composure and 'push around the corner'.

If the bar rates are set on a grippy, dry tarmac road, changing to a slippery wet road will show a car that 'washes out' . So for a car that is right 90% of the time, a compromise roll bar setting will need to be found. Normally this is slightly harder than OE, as the manufacturer's settings take into account cheap, worn tyres, and very slippery conditions.

The biggest variable in this set-up is the driver. His/her driving style and handling preference will dictate a lot of different set-ups. F.i. the acceleration and rate of turing the steering wheel has a huge influence on grip and handling. Some drivers 'hack' the steering wheel, some are really smooth. This will have a direct effect on grip, traction and handling. This goes for braking, throttle contol etc.

So as a conclusion, bar settings are personal. There is no perfect setting for everyone, only a preferred setting for each individual driver

I'll stop rambling now.

Cheers

 

correct me if I am wrong, but wasn't there a big hoo hah about the whiteline antilift kit actually being complete snake oil and almost totally worthless. I was pretty sure that white line got involved in the discussion and had publicly conceeded it was actually a prolift kit but it was too late marketing wise to start changing its name.

I thought the conclusion of that thread coming from the experts too was to stay away and concentrate on increasing castor via other methods.

 

Hi,

Reducing the anti-dive characteristics with an increase in both static and dynamic castor seems to work quite well............... So I don't think it is snake oil.
http://www.whiteline.com.au/articles...WL%20ALK_b.pdf

Cheers,

Job

 

Job, very nice to 'hear' you on Snet again, and to read your concise 'ramblings'.
I found the addition of the Noltec top mounts which approx doubles caster was very significant in the elimination of understeer and general feel of cornering control and the stiff AST springs/damping came a close second.
The thing with the AST and 60/50 springs (sorry Nick, will sort out the lbf/inch) was the confidence value they instilled into my driving the car on hill climbs.

As Job states, it is all a compromise.
Many tell me I am very smooth in controlling steering/braking etc and my runs are very steady..'as if on rails' etc etc (and I'm a bit slow too!) but the spec of my car above and the combination of parts suits me to the ground, but if someone good drove the car, ie John Felstead he might hate it/be slower or go so much faster than me.
Suspension is facinaing!

And those demon Kumho's are something else too. Is'nt that where Job started?

Frazzled Kumhos after a hard weekend of hill climbing


Graham.

 

911,
What miles are you getting out the Kumhos and what compound are you using.
Jools

 

Hi Graham,

I agree, the Impreza likes lots of castor. Nice pictures of your tyres. The graining might suggest that a little bit more low speed rebound could increase the mechanical grip a tad.

How do you find that changing the car's rake influences the balance?

Cheers,

Job

 

The kumhos are the v70a series and as I run 16's I can use the Soft Compound.
These tyres are '1B' competition grade and are road legal.
I managed a whole season of hill climbing and 3000 miles out of them so was well pleased.
The medium compound (I have these on my P1 17's) are MUCH harder and long lasting, all of 6000 miles!

Job:
Thanks for the pm, your killer tech understanding is still there!
As to rake; boy, is the Impreza ever sensitive to front/rear ride height.
I made this discovery early this year when I droped the front a touch and it was everywhere. Restored the setting and all returned along with the peace!

I am tempted to go for the Whiteline 22mm front with adjustable positions to give another dimension to adjustment, but the settings/spec i have seems just so comfortable that the car is very easy to drive fast, especially on the freedom of a track. Do I really want to loose this balance?

I will soon have 'my' next generation of AST's and very much look forward to sorting them out next season which kicks-off in early April, only 4 months away!

Graham.

 

Mmmm, some good techy stuff going on here. Keep it coming.

For my part, I know for a fact on my old Clio (only weighed 950kg), which I did a lot of spring and damper testing on, I reached a spring rate of about 180lb/in where if you went any harder, you basically wrecked the car - too hard for commuting round town, too hard for duals/motorways, too hard to even keep the tyres tracking true on minor mid corner bumps, even braking hard in a dead straight line would see the front end literally hopping up and down 'lowrider' style and yes, braking distances would actually increase. In the end 160lb/in and a bit of fettling the spring lengths, along with a damper rebuild and stroke lengthening is what did the job. Went from being a bone shaker that would corner pretty flat but had nothing else to write home about, to a cracking little Clio that would handle everyday driving in relative comfort as well as lapping the 'Ring fairly swiftly with nothing but a quick twist of the damping adjustment to keep everything tidy. The change that came about by getting the compliance of the suspension spot on was like night and day compared to the setup before.

I'm a firm believer in the power of fettling the ARB now. It's like a win-win situation - I get to keep the compliance of the factory suspension, with the roll control and lessening of understeer of the thicker bar. I'd be pretty wary of going to any aftermarket dampers/springs before exhausting every other possibility.

I did read the Whiteline/Autospeed report on the ALK some time ago, and it seems pretty clear cut there - the ALK does not actually create 'anti-lift' as the name would suggest at first, but instead it alters the factory anti-lift properties, in this case virtually cancelling it out and adding static and dynamic castor instead. A fair swap I'd say? Any more votes from people who've done the ALK mod? Worthwhile or not?

 

BTW in reply to the thing about the different kinds of understeer that occur and possible solutions, I basically would love to go in to corners/roundabout fairly quick, have the front end bite instantly and not plough on understeer at all. Or at least if it did, a quick lift would bring it all back into line.

At the moment oversteer on the exit of a bend is all nice and controllable, once I'm past the apex and the corner's effectively opening out. The problem is initial turn-in understeer when I've gone in too hot, or power understeer because it feels to me like the car COULD or SHOULD get round the corner much quicker and it's frustrating that it won't take full throttle early enough to get the rear into play.

It's basically a question of outright front-end grip I think, or the lack of it. It feels like I've done everything I can with the rear; it's controllable and mobile how I want it. It's now the front end that's just doing its own thing, regardless of what I want LOL

 

Ah, front end bite.
Easy with Noltecs up front, but there is more.
Back to tyres and springs.
I know what you mean about the compliance for the road etc but to focus on a more dynamic approach to cornering, then you need to loose some of the 'OEM' set-up magic.
We are back to Job's excellent ramblings.
I found the Kumho mediums on 17's 'ok'. Massivly better than the Toyo's but...
Then came the softs on 16's and 45 wall ratio 'height'. This tightened the bite. The AST's with the 60/50 spring rates and high damping rates gave another step input to the reponse to direction change.
The stiffer springs (bugger road comfort) the Whiteline 22mm bars and the huge caster angles and huge static camber too realy change the chassis to another level. I reduced the hill climb times by about 1.5 seconds (to die for in the heat of the battle).

On the road the car is great. Harsh/twitchy at times/places but never undriveable, and I can chase the nimble Clio's etc and murder them with 407 bhp on tap....
Sorry, I'm an Old Boy Racer.

Great chat.
Graham.

 

Hi Nick,

Going too fast into a corner will always create understeer unless you deliberately induce oversteer.
But as Graham says, get more castor. The extra loading on the inside front wheel during turns that castor creates works really well on most road cars. Remember how pushing the front wishbones forward on it's bushes to give a couple of degrees more castor on the old Clio gave a huge lap time reduction? Castor works.

ALK, Noltec or K-Mac top mounts, a dozer on the inner wings to push the top backwards, anything to get a bit more castor. It will dramatically reduce understeer.

Mind you, make sure your dampers are working properly. Poor damping will result in a huge loss of traction and grip as well.

Enough verbal dioarhea from me.

Cheers

 

LOL

Think I'll try the ALK first before I resort to the heavy plant!

 

For the cost of the ALK add a little more and fit the noltecs instead!
Do the job right first time.
Graham

 

How much castor have you got with your noltecs Graham? I've forgotten.
Think I managed 5 1/4 degrgees with both noltecs and ALK (comfort ALK gives 0.5 degree)
The more castor the better IMO


Andy

 

That's about right.
Curtis refitted mine to get a bit more.
I have the ALK still on with the Noltec's, and Curtis says he has another trick for the front to come.
Hope to be at Powerstation week after next for the demon suspension.

Graham.

 

If you have ally bottom arms I know what he's on about

<Mr Burns voice>

Excellent !

</Mr Burns voice>

Andy

 

Hi Andy,

The static camber increase seems a small amount but the dynamic castor increase is a lot more. Although I haven't measured it, by looking at the deflection of the standard wishbone bush, I would expect closer to 2 degrees.

Are there not 2 different Noltecs. 1 with poly lining around the Rose joint and 1 without. I think that the 'comfort' one gives less adjustment?

Have you tried the Whiteline castor bush? This gives the added castor without the reduction in anti-lift/dive geometry.

Cheers

Job

 

Andy:
I have the Sti v3 arms, so i guess there is a spacer going in there by the rear mounts?

Job:

I have the comfort ones I think as i was not offered the race ones at the time (it was 2 tears ago.

Graham.

 

Not tried the castor bush from whiteline no, didn't know they did one.
Yep there are two types of Noltecs, both Graham and I have the comfort ones (and comfort ALK Graham, we dont stock the race ones)
Didn't want to go too hard core at the time but may have been the wrong decision
I have spied what looks like an adjustable lower front arm...
Going to see how the cage affects things first..

Andy

 

So tell me more about these 'noltecs' - presumably a modded top mount kind of thing so you can adjust the angle of the strut back and forth from the top?

Correct me if I'm wrong, but I can't see any downsides to having more castor, apart from perhaps more steering effort off centre. With the upside being straighter tracking and better front end bite when cornering, especially from the inside wheel?

 

indeed nick.



Andy

 

They look like a straight copy of the K-mac top mounts. I thought the K-macs were patented?

 

Job,

I've been woke by my 5 week old daughter, what's your excuse for being on SN so early!

I'm guessing adjustable top mounts are noisy?

Regards,

Ian

 

No, or at least mine arn't.
The only noisey mod on my car are the poly bushes in the front. They creak and groan until you are on the road a mile or so and then go quiet.
The bushes in my hill climb 911 were exactly the same.

(I'm not sure if anyone fights patent infringement today (I actually do this kind of work), just eventually a deal is struck/licence granted.)

I had mine from MRT, marketed as MRT Mounts. They are still on thier website www.mrtrally.com.au

They do two things, dial in caster (over double stock caster) and dial in negative camber also to such a degree that camber bolts in the front are not needed even for over 2 degrees negative.

Best mod over the roll bars I ever did to my car.

I find the steering though is heavy and 'wooden', but the performance is well worth the compromise (that suspension word again!)

Graham.

 

I know not what the K-macs are like so wouldn't know if there is any copywright infringment going on.
Agree with Graham that they are not noisey, the most increase on NVH has been fitting the stiffer gearbox and engine mounts to be honest, if the bushes creak then all they need is a bit more grease.

The bit I don't understand is why you call the steering "wooden"?
Heavier yes, increased steer to centre yes, but more positive castor should give you more feedback, not less shouldn't it?

Andy

 

The K-mac top mounts I have used were not noisy apart from motorway ridges. The Rose joint did wear out after a while which rusulted in some clonking. It was a very good modification, but as usual, you want to push the grip boundaries a bit further so 1 mod never seems enough (as I get the dozer out of the cupboard again, 10mm wider chassis at the front sounds a good idea :-)).

Large increases castor does make the steering heavier. This normally results in a slightly dull, wooden feeling (easy to get used to). Modern vehicles that have huge castor angles from the factory artificially make the car feel 'alive' by having the rear roll centre in a strange place. This makes the car feel wonderful but give serious front traction problems and lower corner speeds. If you drive a BMW Mini, it will initially feel really good, but driven in anger, the rear roll centre creates to many front traction problems to make it a good circuit car (understeering pig in other words).

Cheers,

Job

PS. Unfortunatly, I have to get up early every day to look after the dogs and horses before the working day (That pays for these animals) starts.

 

You're right. Just checked some Ozie records. K-mac did take Noltec to court but it looks like a deal was made.

www.k-mac.com



Cheers