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Old 28 Apr 2004, 07:23 PM   #1 (permalink)
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Tracking

Had the tracking checked today at "Humphries" as noticed that the two front tyres were worn a bit more on the outer edges than the inner edge.
The "technician" said that the tracking was "within the limits" :!: He put it down to "cornering".
Dunno if we're convinced with this answer, but does anyone else experience this?
It was suggested that "I go back in 4 months time to swap the front tyres with the rear tyres to give extra mileage".

Do you think it is necessary to get the geometry set up done?

Has anyone else had theirs done and how much is it?
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Old 28 Apr 2004, 07:48 PM   #2 (permalink)
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Well cat, before I got my new tires I went to have an alignment done because my original tires were wearing unevenly on the inside edge. I had installed H&R lowering springs so I knew that changed the suspension setup and probably caused the uneven wear. The tech explained to me that the Toe In/Out tends to cause more uneven tire wear than camber. They said my cars front/rear camber were "within factory specs", but the Toe In was way off. They corrected that and my new tires are wearing evenly so far. If the outside edge of your fronts are wearing first it sounds like your Toe In/Out should be off by quite a bit. Too much Toe Out btw is bad, an increase in Toe In will allow your car to handle better, but the downside is increased tire wear.

I would take your car to a more performance oriented shop if you can, and get a good alignment done.

Also remember that they might tell you it's "within factory specs" that doesn't mean very much because they have a lot of room to play with. It's very misleading.
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Old 29 Apr 2004, 01:38 PM   #3 (permalink)
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tracking

Thanks Gears, your knowledge is priceless! Just need to find somewhere to take it now - any suggestions anyone?
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Old 29 Apr 2004, 04:07 PM   #4 (permalink)
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powerstation in Cheltenham are well renowned for being experts with setting up Scoobs with full 4 wheel laser geometry.

They really do know their stuff and take a long time in setting it up just right with you in the car and out of the car etc.
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Old 29 Apr 2004, 09:28 PM   #5 (permalink)
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Yes, ^^^ that's the kind of place you should really go to. Somewhere that works on sports cars, etc. I bet they can dial in your Catalunya special!

I really need to have a performance alignment done on my car also, it still doesn't track perfectly straight. Hopefully we can both get our cars sorted out. :roll:
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Old 29 Apr 2004, 09:33 PM   #6 (permalink)
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Depending on what happens with my car I may well be going the same route with the full geometry and 'Bumpsteer' mod at Powerstaion. They apparently virtually eliminate all understeer on Scoobs with the setup they carry out I have only heard positive feedback about what work they have undertaken.
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Old 29 Apr 2004, 09:44 PM   #7 (permalink)
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Rich at powerstation is your man.

there are two aspects to the geometry setup- camber and castor.

camber is the relationship on the vertical plane- ie if your wheels slow in or out heightwise relative to the car.

castor relates to the direction the wheels face- looking at the front of the car castor dictates whether the wheels face towards each other or apart from each other.

track settings are different to road settings, and can have an alarming affect on tire wear.

negative camber is generally accepted as better for fast road work- for a very high degree of negative camber see the photos of my track car. the theory is that when cornering the outside wheel will stand more upright and thus give more tyre contact with the road.

my road impreza is running max possible negative camber front and rear- you can get a lot more on the front than the rear though.

castor angle is used more to control handling. I run very slightly negative castor at the front on the impreza- ie the wheels face towards each other ever so slightly. this helps the stability of the car massively.

the rear caster is largely dependent on driving style requirements. if you run slight negative caster on the rear it will usually make the handling quite neutral and safe. increasing castor on the rear can have fightening results- increasing the caster on the rear means that the fronts of the wheels are facing away from each other. this will tend to create oversteer. several people have suggested that this is what they want their impreza to do, but from xperience you have to be a reasonable jockey to handle this as it can be unpredictable.

the current MY imprezas and the MY01s typically run neutral caster in the rear. classics will usually run slight (very slight) neg caster on the rear. I used to run neutral caster on my old classic STi RA, and it handled beautifully in the wet and dry. having said that I knew the car intimately, and it did catch a couple of people out.

I once ran the same car with pos castor on the rear and it was downright dangerous, sticking its arse out at every opportunity. whilst quite entertaining you really couldn't press on safely on the road without lairly slides everywhere.

so there you go. here endeth the sermon. /soapbox mode/ :wink:

hope this helps and that I got the castor infor the right way round- although i know what I'm talking about its sometimes difficult to put it across.

simon
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Old 30 Apr 2004, 08:38 PM   #8 (permalink)
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tracking

Thanx guys for the advice - will certainly give Powerstation a ring and arrange to get it sorted - Cheltenham is not too far away from here - just under 2 hours

Will let ya know how we get on
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Old 30 Apr 2004, 09:22 PM   #9 (permalink)
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That 2 hours is absolutly ideal..... Nothing worse than getting the tracking done and only driving for 5 minutes afterwards
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