antnee
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Registered: 30th Dec 07
Location: Cov Drives: Clio 197
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I need some advise about the geometry of the front end of the Ibiza.
The initial turn in is great, changes direction really well, but the middle and exit of the corner it now just wants to under steer.
I didn't notice it so much on the R888s, but it was very apparent on the Federal 595RSRs which I used on Friday.
What sort of things should I be looking at changing/trying?
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Rob E
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Registered: 1st Jan 06
Location: Madeley, Stafford....I want to live back in Wales!
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There is lots of things that you can try depending on what adjustments you can make to the vehicle.
I would start with a full alignment check on a Hunter alignment machine if possible as these are renowned for their accuracy.
What kind of tyre pressures are you running? A good starting point would be to adjust these. Try increasing the fronts by 1-2psi, this should reduce tyre roll mid corner.
Iv'e also got this flow chart from one of my Uni books which might be of some use to you too. Try changing just one thing at a time though and test it to see if it makes an improvement.
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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if its only through a tyre change that may suggest the tyres are worse 
Too much power on exit? Tyres (esp poor ones) complain when they are asked to do two things - grip lateraly and well as accelerating/braking.
As above - if you have decent castor and camber try adjusting rebound/compression. I've found its more a game of trial and error 
Make a few sheets of paper with tables on them
3x3 grid for responses
Colums - entry/apex/exit
rows - slow/medium/fast
write down your settings, go out and do a few laps then come in and write down whats happening. i.e from above you'd have good entry but understeer apex and exit at medium & high speed. Make some changes and repeat.
It takes the remembering if better/worse out of the equation and gives fallback if you start to get issues again.
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chris_uk
Premium Member
Registered: 8th Jul 03
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When it starts to understeer Left foot brake to bring the front wheels back under control.
Or
Change the driving line
[Edited on 30-05-2012 by chris_uk]
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smcGSI16V
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Registered: 26th May 03
Location: Farnborough Drives: Thurlby 888 CDTi No.98
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quote:
Originally posted by antnee
I need some advise about the geometry of the front end of the Ibiza.
The initial turn in is great, changes direction really well, but the middle and exit of the corner it now just wants to under steer.
What sort of things should I be looking at changing/trying?
Sounds like to me you need to change the shoes you wear from ones made of lead to ones that have better control.
Try changing your driving style coming out of the corner.
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VrsTurbo
Premium Member
Registered: 8th Jun 10
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Federal 595RSRs - that would be why. They are cheap for a reason should of gone for Yoko's instead
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antnee
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Registered: 30th Dec 07
Location: Cov Drives: Clio 197
User status: Offline
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I am usually only coming back on the power just after the apex, so it is already pushing by this point.
I started the day on 28f 26r, ended up 2psi higher on the front and 2 lower on the back for temp reasons.
I went with the RSRs from feedback that they were good, about 90% of the grip of a 888
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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maybe you have just foun the limits of the car? are ibizas really renowned for there handling prowess?
although there are measures you can take, sometimes the chassis design limits any further improvements which is then more drastic changes are needed
[Edited on 30-05-2012 by Steve]
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stevenc89
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Registered: 6th Apr 09
Location: East Kilbride
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iam gonna use rob's diagram to set up some of my cars in forza lol
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
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I get this a bit and its usually because I've turned in too early.
If you imagine moving the apex around the corner a little, more of the actual change of direction is done at the lower speeds, meaning you can wind it off to the outer kerb while accelerating as opposed to still being mid-turn and as Adam says, asking too much from the tyres.
Reason you notice it more on those other tyres is they have a lower grip in total.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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quote:
Originally posted by Steve
maybe you have just foun the limits of the car? are ibizas really renowned for there handling prowess?
although there are measures you can take, sometimes the chassis design limits any further improvements which is then more drastic changes are needed
[Edited on 30-05-2012 by Steve]
I doubt with a standard engine it's anywhere near the limit, considering they're commonly used in Europe at Hillclimb events and seat used the with a chunk more power as rally cars.
150bhp isn't going to push the chassis that much.
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Steve
Premium Member
Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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what? you can drive any car past its limit if you go fast enough into a corner
just some cars are designed better than others and will allow you to go faster before you go past its limit
[Edited on 30-05-2012 by Steve]
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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Although I do agree, if you read what he says it stands to reason that it's not an entry speed problem as the understeer happens on throttle not upon entry to the corner.
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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Can you adjust castor?
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antnee
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Registered: 30th Dec 07
Location: Cov Drives: Clio 197
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AK, Sort of, not as standard but if I get different top mounts I could.
Ian, early turn in could be part of the problem, I used to do it a lot more until it was picked up on when having tuition.
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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castor always helps.... and there are other ways of getting it. Can any of your lower (control arms perhaps) arms be pulled fwd (by swapping to adjustable ones)
I have no idea on an Ibiza setup.
More castor means the camber increases the more you turn the wheels -
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antnee
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Registered: 30th Dec 07
Location: Cov Drives: Clio 197
User status: Offline
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Arms arn't adjustable in any way. I would like to do something with the top mounts, thinking of putting something adjustable in.
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AK
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Registered: 5th Jul 00
Location: Aberdeen City
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you dont really get a lot of adjustment that way...
I know your current arms wont be adjustable... but is there anything you can buy aftermarket to find castor (pull front wheel forwards on its axis )
On the GTR we've fitted arms you can shorten that pull the wishbone/hub assembly forward. Control or tension rods I think they are called
On the impreza I've used top mounts flipped to be angled back towards the windscreen AND flipped the oe lower arm mounts 180deg as they were slighty offset. This pushed the rear of the assembly out and fwd by a tiny amount. I also made damn sure the subframe was bolted as far forward as it could be (slighly slotted holes!)
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