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I spun out in my STI.

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Old 13 April 2002, 09:34 AM
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Boxer
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Happened about a month ago. Very dramatic. Picture a wet rainy night on a not so wide Swiss secondary road, with curves aplenty.
Yours truly has been in awe of the STI's wet weather performance, since getting it in January.
Taking corners like it was dry. Well on this one corner, I did as I frequently do, by powering out of the corner rather early, thus inducing the front diff, to whip the car back into line, this time the road was slippery and when I came out of that corner the front diff did it's magic, sending power rearward, which provoked instant an instant tail out spin,a complete 360 degrees, went off the road onto an empty field, hitting a small wooden road marking pole.
Damage: Windscreen cracked from the stress of going off the road I guess, cause nothing hit it. Front fender dented and side indicator broken from the wooden pole. Revised all the geometry of course. Its back to new, windscreen and fender where replaced.
It was scary, yes the STI is a magical performer in the rain, but be careful, it can have a nasty bite if you don't know it's limits. Thankfully I am now fully aware of the limit of what can be done in the rain with this car.
Think about it before you stomp the throttle on the twisties in the rain, this car lays down more than 253lbs of torque at 4000rpm. We're talking small V8 torque here.
Cheers


[Edited by Boxer - 4/13/2002 9:41:10 AM]
Old 13 April 2002, 10:30 AM
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Dave T-S
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Boxer

Sorry to hear this

Unfortunately I predicted this would happen a while back (not to you!). The front diff in an STi makes it react totally differently.
Old 13 April 2002, 04:23 PM
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yoza
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Lesson learnt!
Move on to the next class
Old 13 April 2002, 04:34 PM
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mutant_matt
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Unhappy

Dave,

And I remember you saying that too......

The main thing Boxer is that you're OK and that you've learn a valuable lesson and walked away unscathed!!!!

Matt.
Old 13 April 2002, 08:54 PM
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Harry_Boy
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Most important thing is you're fine Mate. And the car's repaired and back to its former glory. A lesson to all STi 7 owners there, I think.
Old 16 April 2002, 01:40 AM
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sasman
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Glad you still got the car, Dave was it not me who predicted STI off's with you in agreement I know i'm being sooooo picky.
Old 16 April 2002, 01:58 AM
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Joseph
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Having had a similar xperience in my 7 one has to realise one can't dump power down ***** nilly but feed it in and as it bites counter steer and it will behave sooooooooo sweetly.
J.
Old 16 April 2002, 08:05 AM
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mutant_matt
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Joseph, and isn't that how you drive anyway????

Matt
Old 16 April 2002, 11:25 AM
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Diablo
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Sorry to hear that, but...

Quote

Taking corners like it was dry.


Well it wasn't, it was a wet rainy night

Quote

powering out of the corner rather early, thus inducing the front diff, to whip the car back into line, this time the road was slippery and when I came out of that corner the front diff did it's magic, sending power rearward, which provoked instant an instant tail out spin,a complete 360 degrees.


The front diff doesn't send power rearward, the centre diff does. Is it not more likely that because of the effects of the front diff both front wheels started to spin due to the wet conditions which would accentuate the manner in which the centre diff progressively locked and sent more power to the rear, thus causing the spin.

Quote

It was scary, yes the STI is a magical performer in the rain, but be careful, it can have a nasty bite if you don't know it's limits.


No its not. Nor is any Scoob. They have fantastic traction in the wet, but no more grip in a given corner or "magical" handling prowess than many other cars. Indeed, I would go so far as to suggest that the front LSD will render the STI7 worse in the wet than a Scoob with an open diff at the front, unless you have the car control of Makkinen.

Sorry if you think I'm getting at you, but it scares me to see how many people are driving these cars without a real technical understanding of what all the bits do in any given situation, in different weather. You say that you now understand that it can bite in the wet, but do you really know why? Your post suggests perhaps not.

The fact that a front LSD can, in certain circumstances, reduce understeer under power in the dry without provoking oversteer but increase it in the wet (up to the point where the max available % of torque suddenly goes rearwards as in this case provoking oversteer), is one (very important) point which escapes many.

D

[Edited by Diablo - 4/16/2002 11:29:36 AM]
Old 16 April 2002, 11:31 AM
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helpme
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yeah, in my old 106 ages ago and aproached a dipping roundabout. thought i knew the cars capabilities and mine but obviously didn't as the car spun round with a 180 degree turn and crashed into a kerb. Was a puddle at the roundabout. Nothing happened, in shock and lesson learned. oh and a grit truck coming towards us where we were facing the wrong way on a dual carriage way. went down the wrong way and went round the roundabout again and drove on in silence! I am lucky but some ain't so take it easy people...
Old 16 April 2002, 11:59 AM
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Ditto Diablos comments.

Many people now drive Imprezas due to their bang_for_your_buck and the apparent greatness of AWD, many believe this to be infallible.

Please drive these cars with the respect they deserve.......
Old 16 April 2002, 12:00 PM
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helpme
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yes love the subaru's handling, but every cars have it's capabilities. There's always a limit.
Old 16 April 2002, 01:15 PM
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DavidRB
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The biggest "problem" with the Impreza's handling is that when the car does let go, the car is usually travelling at very high speeds, so there is less time to react and any mistakes will be costly.

Presumably, if the STi7 front diff helps "pull" the car around a corner, this increases the chance of the rear braking free?

Glad you're ok though.
Old 16 April 2002, 01:49 PM
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dowser
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Glad you're OK Boxer - hopefully the biggest lesson learned was not too experiment too much on wet Swiss roads at night

Problem with the front Quaife/LSD in the wet generating more understeer is only once you've already broken traction by entering the corner too fast - if both wheels have already lost grip then both will spin....and no power gets sent rearward. This can also be experienced in the dry on track.

However, slow in/fast out will always promote oversteer...which is nice Best it to find a track to experiment on though.

Richard
Old 16 April 2002, 02:02 PM
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Diablo
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Quote

if both wheels have already lost grip then both will spin....and no power gets sent rearward.


Don't think so. Unless the Sti has a free centre diff, which is news to me....

Yes, both will spin if they have lost grip. They are also likely to spin under power if wet/slippery surface. If they both start spinning the centre lsd will direct power (more correctly torque)rearwards and may cause power oversteer (as appears to have happened above)

The transition from power understeer to power oversteer will be less progressive in these circumstances than with a free front diff.

Another example of people not knowing their cars *shakes head in disbelief*

D
Old 16 April 2002, 02:16 PM
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RT
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I read and re-read this 4 times, but still don't quite get exactly what you mean. Can please explain in a few more words?
Tks!




"The fact that a front LSD can, in certain circumstances, reduce understeer under power in the dry without provoking oversteer but increase it in the wet (up to the point where the max available % of torque suddenly goes rearwards as in this case provoking oversteer), is one (very important) point which escapes many."
Old 16 April 2002, 02:51 PM
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dowser
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D - fair comment, incorrect wording Me trying to explain my findings without thinking it through.

However, fact remains - if entry speed is high enough to break traction before the apex then flooring it generates understeer. If you don't break traction before the apex then the bias is towards oversteer. This is on a my00 with Quaife front and standard centre/rear.

Best experienced on track on a long fast 3rd gear corner - if entry is too fast then more gas (frustratingly ) widens your line. A little bit slower on entry will see the front end bite and the ability to use full gas out onto the straight. Logic suggests that rather than understeer, the above is the result of a 4 wheel drift?

Don't get your point about front diff promoting understeer in wet though - are you saying the centre is too slow to react (ie; not 'heavy' enough) so you're breaking traction of both front wheels?

Richard
Old 16 April 2002, 02:59 PM
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I'll try

A front lsd will generally prevent the inside, less loaded, front wheel from spinning by transfering torque to the other wheel when it "detects" slip.

Unless power is huge, it is unlikely both front wheels will spin in the dry under power, especially with 4wd. If neither front wheels spin, lateral grip is increased (a spinning wheel has minimal (if any) lateral grip) and the power to those wheels will pull the front of the car in the direction they are pointed, hence understeer is reduced.

Also, if both front wheels find grip, centre lsd will not direct proportionatly more power to the rear, which could promote power oversteer in the event rears start to spin.

Clearly this only works up to the limit of the tyres capability to grip the road surface, but with 4wd, and high levels of adhesion in the dry this will be a pretty high limit. Lift off oversteer is a weight transfer issue and not being discussed at this point

In the wet, however, it is much more likely that both front wheels will spin with an lsd. When applying power during or exiting a tight corner, the inside, lightly loaded wheel spins, lsd transfers torque to outside and it spins as well as grip is much reduced 'cos of the water reducing the friction coefficient of the road surface.

When this happens you will experience massive power understeer as neither front wheel has any grip and the car will slide to the outside of the bend. This will only be momentary though, until the centre diff detects that the front axle is spinning faster than the rear.

If you don't lift off the centre lsd will then send more torque backwards. In the wet, this may well induce both rear wheels (another lsd there, remember) to spin giving power oversteer.

If you lift off, you'll either get it back under control or loose the back end due to weight transference depending on whether or not you are going fast enough to create enough lateral loading to exceeed the tyres lateral grip, but thats another story as I've said above .

Basically, the hardware does the same, wet or dry, but grip is so much higher in the dry that the effect of what the hardware does to power distribution is different.

Hope this helps

D
Old 16 April 2002, 03:05 PM
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Diablo
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Richard, yes, centre diff can be - it won't react instantly but progressively (although all things are relative).

Agreed on the the fact that if you are sliding to begin with, more power won't help.

BTW, not sure about your MY00, but UK (non sti) cars have free front diff, limited slip centre and limited slip rear.

Have you had a front lsd fitted as a mod?

D

[Edited by Diablo - 4/16/2002 3:06:46 PM]
Old 16 April 2002, 03:50 PM
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RT
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Tks - agree with what you said. Just didn't fully get your abbreviated explanation before.

You're right. There's (power-on) understeer due weight transfer rearwards and there's understeer due spinning front wheels. The subtle difference is that in the latter, the center diff is redirecting torque to the rear axle, while it's not in the former.

Similarly, there's oversteer due weight transfer forwards (trail braking & lift-off oversteer) and oversteer due spinning rear wheels (aka Tiff Needle powerslide).

Old 16 April 2002, 03:57 PM
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Yup, thats 3 of us know what happens ...LOL....

Hopefully the rest will catch on and NOT crash their Scoobs

D

Notice absence of any input from any other UK STI7 owners other than Boxter's original post.....probably all thinking "****....hope I don't stuff it on the way home tonight" and trying to understand what the **** we are on about here....



[Edited by Diablo - 4/16/2002 4:02:07 PM]
Old 16 April 2002, 05:32 PM
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Adam M
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Diablo, just wanted to say thankyou for that little explanation.

Was incredibly helpful and very clearly explained.

If it s any consellation, I drive the 22B (soon to have a quaife front diff) with extreme fear, and rarely if ever break traction on any wheel for exactly the reasons you discuss, I simply dont understand the dynaimcs of it, and dont want to risk my pride and joy until I do understand and have area to play.

If I smash it in the future, it will be your fault for explaining so well .
Old 16 April 2002, 05:38 PM
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Dave T-S
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Diablo

Five of us (including Mrs T-S) - remembering that unfortunately I posted these very circumstances on here as a possibility about six weeks ago after first test driving the STi7....

[Edited by Dave T-S - 4/16/2002 5:39:45 PM]
Old 16 April 2002, 06:42 PM
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Okay Diablo, I'll bite!

I've had a STI UK for the last six weeks & 2k miles. During that time I've had the chance to drive some very challenging Scottish roads in the wet and take three different STI's around Knockhill (Subaru's demo cars).

I don't profess to be an expert but I did have an interesting chat with somebody who is, the driver of a STI UK with the registration PRO300. Actually it was more of a warning and it sounds like I should have posted already! Sorry!

Mike Wood from Prodrive was at Knockhill last week for the Subaru STI demo day. We were discussing the pros & cons of the new 18" alloys fitted with the new Pirelli Nero tyres.

Mike suggested that with the standard wheels and tyres the car could be rather tail happy exiting wet, low speed, 2nd or 3rd gear, tight corners.

Mike said that if you applied too much power, too quickly, (ie: booted it!) the front diff would do it's job correctly and pull the front of the car in tight to the corner. However this could kick the back of the car out, breaking traction and catching you up rather unexpectedly if you weren't ready for it.

Mike believed that fitting the Prodrive 18" alloys with the new Pirelli tyres would help prevent this since the Pirelli was much more progressive than the OEM Bridgestone.

Obviously this could just be a sales pitch to part me with another £2k but from the driving I've done since I'm convienced it's true.

I went for a 200 mile run through the Scottish Borders last Sunday and a lot of this was down wet, narrow roads with plenty of tight corners. The car never understeered once, as soon as you applied power to exit a corner, it just hooked up and took off. However if you applied too much power then the car pulled really hard to the inside of the corner, upsetting the balance and requiring steering input or a slight lift of the throttle to correct.

Hopefully you can see where this is leading........

Regards, Mark

Mike Wood- A thousand apologies if I've misquoted you. As punishment I promise to go around Knockhill as a passenger with you again!
Old 16 April 2002, 11:23 PM
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Diablo
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Talking

Mark,

Agreed, if you get traction wet or dry, fron diff will pull car into the corner upsetting the balance. My Old Teg did this too, but a lift sorted the problem out (less prone to lift off oversteer)

Chances are, if you've got traction, you are travelling pretty fast in the wet and this may = BIG accident

On tighter, slower speed corners, you'll get both fronts to spin, and this will give the understeer to oversteer "moments"

Try it on a quiet roundabout, with care. Better still a skid pan.

Happy motoring all

D

(Counting 6...LOL...)
Old 16 April 2002, 11:32 PM
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mutant_matt
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Mike believed that fitting the Prodrive 18" alloys with the new Pirelli tyres would help prevent this since the Pirelli was much more progressive than the OEM Bridgestone
Mike pushing Prodrive products.......never

Matt
Old 17 April 2002, 08:32 AM
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X SOOOBY
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when i test drove the sti it was in pouring rain at one point i made a u turn on a right turn point on a duel carriageway i booted it and woah the car took me sideways for 25 yards
i couldn`t beleive it as my my00 just powers it forwards in the right situation
so now i understand from your comments that you have to drive the car in a different way to get the best out of it
so anyone who is upgrading from a classic shape should relearn how to drive a scooby
oh and by the way i made these similar comments before about this and certain people said i didn`t know how to drive etc...

[Edited by X SOOOBY - 4/17/2002 8:57:37 AM]
Old 17 April 2002, 08:48 AM
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Dave T-S
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And if you want to drive a REALLY wayward STi7, do it with one that has OEM tyres and 1.7 bar boost spikes

Under hard acceleration it would pull you from one side of the road to the other if the camber was bad, and if you were changing gear and only had one hand on the wheel whilst having a bit of lock on it would nearly yank it out of your hand

Wahoo, took me back to my Astra GSI days.....
Old 17 April 2002, 09:43 AM
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Adam M
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LOL,

how many of you have driven a 22B?
Old 17 April 2002, 10:51 AM
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Dave T-S
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Was that an offer Adam


Quick Reply: I spun out in my STI.



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