Palmo

Hi all - this is my first post on here and I'm after some advice regarding steering problems on my car - 2002 WRX Impreza with engine mods around 280bhp and lowered with prodrive / eibach springs.

Recently had full geometry set-up (see below for before and after settings) at a well-known scooby specialist. The car didn't particularly handle bad before but I was getting odd, uneven tyre wear across the tread pattern (not just on the inside edges as I believe is common).

Afterwards when I took the car for a test drive the handling was indeed improved with better turn-in etc. However the car has now developed a tendency to wander / pull to the left on the majority of road surfaces especially on the motorway at cruising speeds. The car has definitely not suffered from this problem previously in almost 3 years of ownership.

I revisited the specialist who advised the car had been set up perfectly and that these settings couldn't be causing the problem. It was suggested that the uneven tyre wear on the Bridgestone RE11's could be the cause. I took the advice and changed all 4 tyres for Toyo T1R's on recommendation. These have improved handling even further, along with improved ride quality and reduced road noise. However the car still wanders to the left.

The geometry settings are as follows:

Item: Before: After:
FRONT
Caster Left +2,59' +2,55'
Right +3,23' +3,19'
K.P.I Left +15,25' +15,27'
Right +15,06' +15,04'
Camber Left -1,34' -1,05'
Right -0,51' -1,05'
Toe Left +0,6mm +0,4mm
Right +0,7mm +0,4mm
Total +1.2mm +0.9mm
Set back +3,0mm +0,4mm

REAR
Camber Left -1,39' -1,38'
Right -1,25' -1,38'
Toe Left +0,6mm +0,1mm
Right -0,9mm +0,1mm
Total -0,4mm +0,2mm
Driving Axis Thrust -0,06' - 0,00'

Can any of you experts offer any ideas what the problem could be as this is spoiling what seems to be a great handling car otherwise. Also since having the new tyres fitted I am getting very minor wheel vibrations through the steering wheel. Each of the tyres has a small yellow circle stamped on the sidewall, should this be aligned with the tyre valves? None of them are - is this a possible cause or just poor wheel balancing? Again, there was no vibrations previously although I must stress these are relatively minor.

Your advice and comments would be greatly appreciated.

Cheers

Martin

Palmo

Forgot to mention in my original post that I also have rear proflex anti roll bar drop links installed - this was prior to the geometry set-up though and didn't appear to effect the car in a straight line.

Fuzz

drop links wont effect the geometry in any way
Even camber on the front, not too agressive.
toe is equal at 4mins positive
Rear camber looks a litle aggressive for a road car!
and the car is travelling in a straight line (thrust axis)
Rear toe could do with a tweak if being fussy but other than that looks fine.
I'd suggest taking it back to whoever it was and get them to check it over and check everything is still where the print out shows it to be and everything is tight.

Andy
Hope it wasn't ME

Palmo

Andy,

Thanks for the info, and no it wasn't you who did the alignment. I don't really want to name names as I don't wish to give out bad press - just want to get my problem sorted, although I will say it was by a well respected place in the Midlands.

Being relatively new on here (and a little nosey) I see you are in the Cheltenham area. Do you work at Power Station by any chance? I've heard great feedback from customers visiting there - just a little too far for me to travel.
When you say that the "rear camber look's a little aggressive for a road car" and "Rear toe could do with a tweak if being fussy" could either of these cause the problems I'm experiencing? If so what should these settings ideally be?

I'm also wondering if it could be that the car is now more "precisely" set up and simply following the cambers of the road more sensitively (these do tend to be generally towards the kerb I know) than before?

Martin

Fuzz

Yes, you got me, I work at Powerstation (now in Tewksbury by the way, no longer Cheltenham)

Thank **** it wasn't me then.

I'd of set the rears to about 1,30 at most (1.5 degrees)
and the toe to 0,02-0,04 positive
Fart on the laser and the thing would change by a minute or so that's why I said if being fussy.

excessive camber would certainly make the car "tramline" (follow undulations in the road) but would have expected that to be more prominent on the front axle rather than the rear.
The bosses know more than me (ex rally drivers and all that) so I'm sure you could ring them and ask thier advise on that (ask for Dirk)
Advise is one thing that's free.


Andy

Palmo

Andy

Must say that when I initially drove the car after the geometry set-up it felt much worse than it does now - was tramlining quite badly although it was the pulling to the left that stood out (I drive 60 - 70k a year for work in a company car and have 2 pet hates "pulling over" and "wheel vibration" - it seems I have both on the scoob at the mo). Changing the tyres effectively reduced the tramlining considerably although hasn't removed the pulling over.

Regarding the new tyre's I am also getting minor vibrations since fitting, as mentioned in my original thread also, at 75 - 80 mph (I've posted about this in the wheel section). Each of the new tyres has a small yellow circle stamped on the sidewall, don't suppose you know if this should this be aligned with the tyre valves? None of them are. I have read elsewhere that the tyre should be fitted with the yellow mark's positioned to line up with the wheel valve as the mark's indicate the lightest point of the tyre determined under static balancing conditions whatever that means? Does this really make a difference and could this be the cause of the minor vibration?

Martin

Fuzz

the makers of the tyres mark the lightest (out of balance) part of the wheel.
Now in theory the heaviest (out of balance) part of the wheel should be the valve area.
Hence why the two parts should go together aligned..
HOWEVER I have yet to see a wheel when put together with a tyre in the right place make any difference what so ever to the balancing process, hence why nobody bothers.

If you have vibration then the wheels are out of balance and can be set right with the correct amount of weight in the right place. It matters not whether the marks line up with the valve...


Andy

Palmo

Cheers Andy for the good advice - it's appreciated!

Fuzz

another reason is the shocking state of some "new wheels" mostly the cheaper cast stuff,
it never looks round and true let alone in balance!!!


Andy

Palmo

I just have the original WRX wheels (haven't got around to upgrading yet - spent my money on engine and suspension mods's todate). The guy fitting the tyres even commented that my wheels seemed to be in excellent condition with no visible bends at all - never kerb etc. and have covered approx. 36k miles.
The vibration is minor I must be honest, but never the less, I would not have expected to get any vibration from new tyres when the old unevenly worn tyres gave none - I will go back and get them re-balanced.

Fuzz

ANdy

DuncanG

Its a good idea to put a mark (eg wax crayon) next to the valve when fitted so you know if there has been any rotation on the wheel. When the tyre is fitted its lubricated with soft-soap and it takes a couple of days for that to dry up or get washed away. In the first couple of days its quite easy to rotate the tyres on the wheels with hard braking or acceleration and so throw out the balance.

Palmo

Anyone else suffered similar wandering / pulling over problems (especially after geometry alignment)? If so what was the problem?

Hoppy

Martin,

DuncanG makes a good point. I used to mark my new wheels/tyres like this in case I had to hit the brakes hard in the first couple of days. But I never did, and now don't bother. It's a very good precaution, though.

Richard.

DuncanG

Palmo, does it still pull left on a flat level surface, like a car-park? Its not just running down the road camber is it?

I've heard that asymetric caster can be used to compensate for road camber, but can't remember which way it goes. Accademic anyway unless you get adjustable top-mounts.

Palmo

Pleased to say I have virtually got the vibration problem cured! See thread in 'Wheel section'.

On the pulling over issue, the more I drive the car the more I'm beginning to wonder if it is simply more camber sensitive since the new geometry set-up. The car definatley pulls to the left now in places it didn't do previously (I've had nearly three years experience of driving the car on the same roads and can tell a difference). There are stretches where it doesn't pull though and if the road is obviously cambered to the right then the car wanders to the right as you would expect. It certainly doesn't tramline now with the Toyo's so maybe it is simply the way the car is set-up. UK roads are so crap that it can often be difficult to estimate the level of camber on a given stretch of road and coupled with the pot holes and repairs that are clearly raised / sunk our cars do take a battering just cruising around.

Has anyone else found similar things ocurring after geometry alignment?

911

Yes I have, and it varies from road to road.
My geometry is radical and on one local stretch I need to turn the wheel about 5 deg to keep going straight.
Motorways are a dream, and the very twisty bits a really good dream!

got used to it now.

Graham.

LoFi

From my experience I think you will find the increased camber does make the car seek out those imperfections in the road more. I also find the car with high camber can be very sensitive to tyre pressure. Mine certainly was when it ran slightly more front camber than your. On one specific piece of road it would pull quite hard to the left and you could guarantee that the near side pressure would be slightly down. Have the pressure spot on and no pull at all.

I now have mine set about the same (front camber) as yours and it is much less sensitive to tyre pressure (and hopefully wont kill the inside edge of the front tyres quite so quickly). But I'm not happy with the front end bite now and would go back to a greater camber when I can.

LoFi