Andy.F

Mycroft

Is a Macpherson strut set up that complex ? I thought RC height could be established from a line extended from track control arm to intersect with strut top mount projection - back to contact patch ? RCH being where it crosses the C/L ?

I realise how the castor will influence its fore/aft position but had never really considered this before..............

K9VYN [Kevin W]

Cheers Evil,

Have had some oversteer and many understeer moments in the Scoob. Obviously in the dry you can just feed in more power and more lock and the car despite progressivley understeering still corners - used this to great effect at Cadwell Park and Donington.

The scooby allows me to correct oversteer quite easily, but not to the point where I could say I was confident that I could induce it and control it to the a greater or lesser degree.

Kev

elondan

Simon I checked it and you're are wrong,
Satndard Scoob has an LSD both in the middle (Front and rear) and a rear LSD.
so the car will move the power to the rear like I said and felt in my car.

TomM

Ive driven/owned FWD/AWD/RWD, and I have to say that RWD is the best fun, AWD best for really ragging it and FWD is good for disabled scooters. Just MHO.

elondan

Simon,
one more thing I have Subaru's books (Got it from a friend in Subaru Israel) to prove my point.
and if what you say was true, so how come you don't have torque steer?
Subaru's understeer like a RWD when coming into a corner but once in it and coming out under power you'll start to oversteer.

darkblueturbo

forgive me, only just started reading this thread and from webmaster on page 1:
"Don't get me wrong, I love my scoob, and really REALLY love AWD. It is just important sometimes to not get carried away and think they are the savious of the universe. And they REALLY can catch you out if you're not ready for it. Everything is so easy when you're on the gas, but go into a corner too fast and have to lift and they're just as difficult as any other car to hang on to.. the difference is that you are all relaxed as they were so easy until you lifted your foot."

I a lane I used to drive all the time (5 times a week) in my first sport, I was a bit hot into a left hander for the conditions; October leaves on the ground, wet, night.
Being an inexperienced driver I lifted of the gas and all hell broke lose. overcorrected a couple of times before doing a 180 into a field. The farmer was plenty pissed cos he'd just replaced the fence after someone else had done the same as me the week before.

Never driven quite so fast round the lanes since that day! An advanced driving course may well be in order. Any suggestions? I'd like to know what sliding the car feels like in controlled conditions and how to drive through and hold it, rather than panicking off the throttle and smashing it to bits.

uxg

Just to add another equation into the mix I drive a Type R which has the active centre diff and in it's normal position it seems very tail happy, alomst like my BMW 325 I had previously although probably not as bad. No I know most good drivers would probably think this is very good with several people posting on this thread saying that they would like to have the active centre diff.

However I am not a brilliant driver and untill I get my advanced driving courses sorted out would prefer a car which was a little more stable in the corners. Now I know I should just be able to click the active diff forward a few notches but I have heard many horror stories on here about how this isn't a good idea at all if you don't want to damage the diff (although to me this defeats the point of having it in the first place) so is there anything I can do, besides learning how to drive a bit better very quickly to stabilise this.

Plus the car also tends to feel very wayward at the back when breaking hard even in a straight line??

EvilBevel

Darkblue, the standard answer used to be "The Wetter the Better" (Don Palmer at MIRA) but I'm not sure if he still has access there. He may still do the course in other places mind. Anyone have any info on this ?

What you experienced was the famous "LOOS", and as I said above is the exception to the rule when talking about the "obedient" understeer character of the UK scoob.

The theory is rather simple: you possibly experienced a bit of understeer when committed to the corner under power, possibly turned a bit more into the corner without much effect, then suddenly were lifting off ("oooh shiiiite), causing a massive weight transfer from rear to front. Front tyres grip again, back becomes very light, and tara... let the fishtailing begin.

Mind you, the same effect could happen with a RWD or FWD, the Scoob just makes it a tad worse by also engine braking on the 4 wheels - and thus also the front tyres, giving them even more grip all of a sudden etc. Simplified & exagerated, you might say that suddenly 80 % of the car's weight is over the front tyres, only 20 % on the rears (fake numbers), and since the rears are also engine braking, they have even less lat. (cornering) force available.

The answer would have been to *gradually* get off the throttle if you were really overdoing it. This would have enabled a bit more grip on the front tyres (without the "sudden") aspect, allowing you to finish the corner without drama.

Courses are great to see what happens to the car, but sliding it around should (IMHO) always be confined to a track / course etc... the public road just doesn't really give you enough space in 99 % of the cases, especially when you get it wrong.

One of the options you do still have is book a trackday via the SIDC or via easytrack etc to do an airfield day. You can get instruction on most, and if you make a mistake, there's usually just cones and lots of tarmac to catch you. Bedford, Elvington or Bruntingthorpe comes to mind, although it might cost you a set of tyres

As for the other comments: Elondan, I think you need to have a closer look on what happens exactly with our cars, how & when the LSD's work. Funny, to get torque steer reactions in a UK car, just install a mechanical front diff BTW

Simon is *absolutely right* about the Subaru AWD sending the torque forwards (and in tight corners, mostly to the inside wheel) when on power through a corner... the inside front wheel spinning helplessly . Please don't tell me you never experienced that ?A front fast acting diff - not the open diff we have on most UK cars) helps a bit, but *still* doesn't turn the Subaru into an oversteering car.

And as for "RWD understeering going into a corner"... very puzzling... how exactly do you go into a corner ? Way too slow, still applying throttle, understeer like a pig, then brake ? then try to make speed up under power ? Sounds very much like my clumsy driving style but it is all wrong. Assuming you are braking before the corner (!) you will load up the front/make the light go rear, possibly even worse when trailbraking (braking well into the start of the corner), you'd then ideally be on the edge of grip without accelerating at all, giving your tyres maximum lat. grip until you are past the apex. Only then acceleration comes into the picture... and unless you have a 22B or typeRA with a *serious* centre diff (or an Evo...) with a rear biased torque split, you will never make it into a power oversteer monster.

Don Palmer made it very visual:
"suppose you have 13.000 BHP and you push the throttle, what happens to the car if you floor it ?"
"Erm... it would lift the front wheels ?"
"Exactly, you dumb Belgian, now get your oversized foot off the throttle you moron . How do you steer with the front wheels lifted?"
"Erm, you don't as you have nothing to steer with ?"
"Exactly. Leave the throttle alone until after the apex, then gradually feed in the power/balancing between cornering & accelerating. Turn in later than your instinct tells you."

If you need power in the first part of the corner, you went in too slow to begin with. (we are talking basics here, not WRC cars etc)

Is he wrong as well ? Poor Jackie Stewart

Simon didn't invent this stuff mind, it can be found in any serious book, or told by any instructor. And if you don't do books (other than Subaru books of course), any serious driver can tell you this is just the way it works. (and no, I'm not a serious driver)

"Drive to Win" from Carrol Lewis gets my vote every time.

PS: "leave the throttle alone" means "constant power, not lifting off, not accelerating, almost steady state cornering".

[Edited by EvilBevel - 8/21/2002 5:53:35 PM]

darkblueturbo

Quote:
The theory is rather simple: you possibly experienced a bit of understeer when committed to the corner under power, possibly turned a bit more into the corner without much effect, then suddenly were lifting off ("oooh shiiiite), causing a massive weight transfer from rear to front. Front tyres grip again, back becomes very light, and tara... let the fishtailing begin.

evilbevel - this is not theory. This is EXACTLY what I did.
M_U_P_P_E_T! Cost me an Impreza that did!

elondan

I mean what the car will do in extreme conditions:
Understeers when going into a corner...if going in too fast!!
and I don't know whats wrong with your UK cars but my GT never spinned its front wheels when pushing it through a corner, rather moved the power back!
and I know the difference between power oversteer and lift off oversteer... give me a break.

EvilBevel

I hate to turn this into a slaggin match again, as it is an important topic, BUT:

This was you that said this, wasn't it ?

This means you haven't got a clue and I won't give you a break.

Clear ?

Want another URL of wrecked Imprezas Elondan ? Last time it seemed to tickle your fancy ?

Darkblue: don't feel bad, it's a classic mistake, and threads like these could prevent other people stuffing it if it wasn't for people thinking they know better & clutter the real information. My guess is that 50 % of all stuffed Scoobies are due to LOOS. Won't make you feel better, I know, it sucks to stuff a nice car (or even a non-nice car) ...

These topics could be fun/educating, but are always spoiled by halfwits pretending to know what happens.

Do you work for Lotus Elondan ?

Simon is a tw@t just like the rest of us , but he may, possibly may, just have a point or 2 here. What the f*ck on earth makes you think you know better ? Your posts don't seem to point at knowing better anyway.

Post something that makes me think "hmmm, he may have a point".

The internet disgusts me more & more, and I love it

Andy.F

For what it's worth, I tried a little experiment on my car, I adjusted the throttle stop open further. To an extent the ISC valve will close in to compensate therefore the idle speed does not rise, but ....here's the clever/dumb (delete as appropriate) part -
When you lift off at high speed, the ECU still fuels the engine as it detects the throttle still slightly open, this lasts for approx 4 seconds until the ECU works out whats going on, this virtually eliminates initial engine braking, I have observed 4 side effect from this.

1 - The car does not transfer so much weight if you lift off mid turn, turn in is more relaxed with less chance of a fishtail

2 - There is less lag between gear shifts as the turbo doesn't slow down as much.

3 - You can no longer shake off pesky understeer by deliberatly snapping the throttle shut in a turn

4 - Your brakes get a hard time due to the extra work

Andy

elondan

The fact you speak and write better in English doesn't make you right!!
you haven't got a clue what I know or don't know or even who I am.
you can keep on writing BS it doesn't make you right,
I as opposed to you dug up some books from Subaru and read the whole thing, I also read what some journalists say, some of live here in Israel.
and yes RWD will understeer more than FWD coming fast into a corner, after entering the corner its a whole different ball game.
as for the crashed Scoobs, what are you? 12 years old,cause you act like one.
I asked for it, to see how safe are these cars, cause my brother wrecked mine and it saved his life,
but you are so childish you probably don't understand why there is a site for "ENCAP" "IIHS" "NHTSA" "OSA"... or why are people so fascinated as to what happens during crashes,
but why do I even bother explaining myself to someone who calls himself "EvilBevel" WTF...

Mr_TonyC

I think you'll find he drives the car rather than reads about how it should react. Try it some time and learn something.
You are talking rubbish.

elondan

I read about the system!!! not the driving!!!
I've been driving Imprezas since 1995!
I understand you all worship him, and I never in any of my posts put him down, I still disagree with him,
a concept you people don't even dare think about!!

roee

How the Impreza survives crashes got nothing to do with ANYTHING on this (quite entertaining and educating) thread.
Due to the increased engine braking as a result of lifting off, it's prone to oversteering. That's quite simple.

You can't tell what would understeer more entering a corner, FWD or RWD, unless you state the throttle position in the entrance. Assuming the dear bloke has shut the throttle close, the FWD will get increased engine braking due to weight moving forward and granting more grip to the front tires, but the RWD will also have braking forces operating on the rear tires while FWD will not. So you can't determine it for the general case.

The only Impreza I've driven was a Group N car with an adjustable central diff. It understeered like hell unless you gave some more traction to the front tires - i.e. trail braking - and then applied power. Only then it really went sideways nicely.

elondan

"Last time it seemed to tickle your fancy " my reaction was to this sentence, and ROEE if you just want to argue lets do it in hebrew!!
oh and ROEE if you ever come to the mifgash I can prove it to you on my Impreza.
and if we're talking about a car like the STI 7 this thing gets its tail out so easily and naturally its silly. the only difference you still have the front wheels in case you need them.

EvilBevel

OK...

Which explains it all. Weakest link & all, goodbye. No further need to expose you really.

Ta Tony

Andy... you're putting me in a difficult spot here... OK, as a very bad driver, it always confuses me how forgiving the Scoob is on track actually (lift off at wrong moment, inadvertently trail braking etc), and the things you say make me go "yup, must be true".

I wonder if Subaru engineers have put a lot effort in trying to eliminate LOOS. What you say could prove that really.

OK, given overconfidence, leaves, damp conditions etc, it may still not be enough, but on track I find the Scoob to be ultimately forgiving, and indeed, just lifting off doesn't send it haywire ... almost feels like left foot braking/stupid antics are needed to get the back out. Function of ECU/idle control valve ? Need to think about this a little more.

Food for thought... hmmmh...

roee

Why argue in hebrew only when we can do it in BOTH languages, in two different forums, in parallel! lol

I think the point is being missed here; AWD can be calibrated using the differentials. I'm sure a Skyline is tail happy, despite being AWD.

The reviews I read of the STI7, all pointed that it understeers a bit more than they like, unless you really use the front ATB diff and even then it's not proper oversteer but merely line tightning.

Still you have NO absolute control like RWD has.

But I do agree on one thing: I'd be more relaxed driving an STI7 fast ON A PUBLIC ROAD than I'd be happy driving a similar RWD car.
On a track, it's a completely differernt matter.

elondan

that explains it all, and as such I should treat you!!
have you ever exprienced 4 wheel drift...do you even know what makes your car so good and why all these magazines like it??
NO, you probably think its because of the straight line power...

EvilBevel

And still know fvk all about driving... amazing

So for the record... RWD cars "understeer" on corner entry ?

Yes ?

Go on, make my day

EvilBevel

roee, with all respect, but I think I covered that in my previous reply. Of course diffs make a big.. erm... diff

Can I join in on the parallel discussion, or is this forbidden for goys ?

EvilBevel

Absolutely spot on as they say BTW. Very true.

elondan

You're the one that's a "bad driver"...
read this from "AUTOCAR":
"So, where the understeer-prone BMW M3 would eventually wash out wide at the front no matter how much extra steering lock was applied,"

"The BMW suffered from understeer in this test too"

and this on the Impreza:

"a properly sorted four-wheel-drive car like the Impreza will blitz any two-wheel-drive rival in virtually any objective handling contest, the incredible realisation being that it does so in this instance with as much - if not more - feel than any of its rivals. That's a truly astonishing result given the quality of the rest of the field."

roee

Sure, this is an old debate we carry for some time now, LOL

Sorry for missing the differential parts

And completely off topic - as a Belgian, do you any track in Belgium that has plenty of open track days (not like every third sunday or something), or is it necessary to go all the way to the Ring? Thanks alot


[Edited by roee - 8/22/2002 12:12:55 AM]

elondan

Thats what Autocar thought back in 1998:

http://www.users.totalise.co.uk/~sco...s/handling.htm

EvilBevel

roee, alas not... track days are still very rare over here. The Zolder circuit has a few ( http://www.circuit-zolder.be ) and I think a UK company (wheeltorque ?) does combined Francorchamps/Nurburgring days (expensive though), but most of the time it is on Tuesday only, unless full moon or shoe size 45 kind off scheduling

I've only driven Zolder 3 times, and I'm dying to have a go at Spa to be honest.

So the Ring is your best bet - although it's very unforgiving & dangerous. But it's still the mother of all circuits.

roee

Thanks, Apparently i'll have to go all the way to the ring. Got any estimation of the distance from lets say Brugge to the Ring?

Thanks alot again!

roee

And back on the topic - That Autocar article isn't really significant, Most tests were a testimony for the Impreza's excellent chassis and not related to the type of drive it uses. Ultimately, around a track I don't think the Impreza excells any more than a compratively powered RWD car.




[Edited by roee - 8/22/2002 12:35:55 AM]

EvilBevel

Bruges to the Ring is about 370 Km. Depending on time of day, progress can be made, but say 3,5 hours is realistic (can be done faster)

If you want to drive, try to go on a weekday, but if you want to see all kinds of cars, weekends are nice as well.

If it's a first time... just take it easy </serious>