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Super twitchy at speed

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Old Feb 28, 2023 | 03:58 PM
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Default Super twitchy at speed

Hi all,

Need help with the scoob!
It's super twitchy at speed/Accel

04 WRX wagon:
Tein flex Z lowered 25mm all round
22mm front ARB + drop links
24mm rear ARB + drop links

Done the bushes on front and rear control arms .

Car does not feel stable at all really sketchy at 70mph.
Checked my tyre pressure and they are all even 37.5 all-round.
Tyres are 215/45/r17 tread wear is even



Do the alignment figures look alright? / Any suggestions on what to do?

Cheers

Nick
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Old Feb 28, 2023 | 04:51 PM
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Factory tyre pressures F: 33 R: 32
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Old Feb 28, 2023 | 05:42 PM
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A little bit of toe in should be agile but straighten up a bit at speed, not sure starting with toe out like you have now would help? Looks like you could do with more negative camber also? Some suspension guru should be along soon to check it properly and have decent input.

Last edited by forgedmarco; Feb 28, 2023 at 05:43 PM.
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Old Mar 1, 2023 | 08:14 AM
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Originally Posted by Newscoobyman
What tyres do you have?
Yoko advan sport 215/45r17 👍
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Old Mar 1, 2023 | 08:35 AM
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Bottom line is that wrx wagons do get worse with speed, but the enormously thick arbs can't help. My last wagon was terrible over 110 mph.
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Old Mar 1, 2023 | 08:57 AM
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The over inflated tyres as Don mentioned won't help.
The rear left has positive toe (toe out) which won't help with stability.
You need around -.0.04 toe in per wheel at the rear.
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Old Mar 1, 2023 | 09:24 AM
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Also, when it was lowered, was the roll center taken care of by fitting extended ball joints? This alone would make it handle like a dog.
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Old Mar 1, 2023 | 09:48 AM
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Coilovers and big bars are not ideal on the road - you've lost suspension independence.

What are your wheel centre, vertically upto arch, measurements? - too low and you're constantly engaging the bump stops.

Start with 33psi front, 28psi rear tyre pressures.

How have you got the front camber plates positioned? A pic would do.
Are the rear top mounts adjustable or stock rubber?

Your alignment is in degrees, not the more usual degrees and minutes:
Zero front toe
Front camber negative 1° 45minutes (negative 1.75°), per side. Less if you're always on the motorway/A-roads and you want to reduce tyre wear.
Rear camber is not listed as adjustable. But you can minimise and equalise, using the play in the lower mounting holes: negative 1° 30minutes (negative 1.50°), per side, would be nice.
Rear toe: Positive 0°03 to 0°04minutes (positive 0.05° to 0.065°) toe-in, per side. Most of the straight-line stability comes from here, on the strut rears.

Last edited by 2pot; Mar 1, 2023 at 12:47 PM.
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Old Mar 3, 2023 | 02:57 PM
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Originally Posted by hedgecutter
Also, when it was lowered, was the roll center taken care of by fitting extended ball joints? This alone would make it handle like a dog.
Roll centre wasn't done no :/

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Old Mar 3, 2023 | 02:59 PM
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Originally Posted by 2pot
Coilovers and big bars are not ideal on the road - you've lost suspension independence.

What are your wheel centre, vertically upto arch, measurements? - too low and you're constantly engaging the bump stops.

Start with 33psi front, 28psi rear tyre pressures.

How have you got the front camber plates positioned? A pic would do.
Are the rear top mounts adjustable or stock rubber?

Your alignment is in degrees, not the more usual degrees and minutes:
Zero front toe
Front camber negative 1° 45minutes (negative 1.75°), per side. Less if you're always on the motorway/A-roads and you want to reduce tyre wear.
Rear camber is not listed as adjustable. But you can minimise and equalise, using the play in the lower mounting holes: negative 1° 30minutes (negative 1.50°), per side, would be nice.
Rear toe: Positive 0°03 to 0°04minutes (positive 0.05° to 0.065°) toe-in, per side. Most of the straight-line stability comes from here, on the strut rears.
Cheers for the detailed reply mate, dropped the tyre pressure to 32f 30r and it handles much better straight away.

Away from car currently but I'll get photos of top mounts they are adjustable.

I've got rear camber bolts but nothing more than that 👍
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