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Wheel Alinement


Philip_98
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if anything the guy will let you know if he spots anything. such as tyres or may be a seized track rod end arm.

at 47k you should be good and the alignment makes a big difference to the handling and drive'

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So it's about -15mm lower than non-sport and oil dampers. Can i ask why your going onto coilovers? If you intend the slam it then you will need additional front camber adjusters unless tyre wear is not a concern. The rear camber should be fine with the OEM adjusters since the pickup points are near vertical.

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Springs where put on by the previous owner so i assume so, dont get what your meaning about what settings am i going for? is it not pretty standard what it should be? and im putting it on coilovers because it sits to high at the back and imo looks daft

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OEM geometry settings would de-tune the modification, whereas what should happen is a bespoke set-up to enhance the chassis into two areas...

1: Tyre preservation if tyre wear is an issue

2: Fast road/ track type of calibration where handling is the dominant desire

Fact is you can't have both since no modification is without consequence. Historically owners want to surf between the two options thus enhancing the handling but understanding there will be some sacrificial tyre wear. Point is you cannot and must not allow OEM settings to be applied.

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Other things fall into the mix like.... If you have up-rated roll bars, polly's, aftermarket wheels, then offset, spacers and so on.

On top of all this the end calibration would depend on the OEM pre-installed adjustment range. It only takes one adjuster to run out of range then the entire calibration will need to be born from that position. For example you can't have three wheels set for fast-road and one set at OEM levels, it would handle pants.

Historically you would be safe with OEM adjusters to -50mm, after that additional front camber adjusters would be needed. -60mm you would also need rear adjusters.

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Only thing that is done at the moment is sport springs and 18x8.5" wheels with ET44. the garage uses Hunter Geometry 4 wheel alignment. Im happy enough with the uneven wear as i know that its always going to be there due to the is200's set up

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Then the only unknown factor is going to be the coil rates your shooting for, i would think around 500r 600f if your going for a fast-road come fun track day.

On the Hunter they need to measure the end position of the "Rolling force lever", hard to explain but they should understand, This ensures the final camber and SAI ( Steering Axis Inclination ) provide the same size tyre contact patch under the steer pivotal axis.

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Bet you will know more than them now ;) .... Fact is the cambers need recovering and balanced front and rear. On the sport springs these are the settings i would shoot for

Rear

Camber: -1 degree 20'

Toe: +8' per side

Front

Camber: -50'

Castor: As high as possible

Toe: +4' per side

They will tell you the castor is not adjustable!..... It is but indirectly VIA the camber adjustment?

To explain.... When the camber is moved it will dramatically displace the toe position, as this is corrected it will indirectly adjust the castor position and move it toward positive, this is a good thing!

In addition the front steering arm lock nuts will be seized like a *****, a wire brush to clean the threads then some heat ( not glowing ) will deal with that.

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Meant to visit "Atomic" to get the wim done

i'm sure they have all the setting as heard many club member go there :innocent: they do a lot of the IS200 model do they?

would be a different setting if it's been priviously lowered :geek:

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I shut down our operation at Atomic sadly....... I re-wrote the geometric settings for the IS200/ 300/ SC some years back after the owners of this forum contacted me regarding the issues members had with front tyre wear, sadly Lexus got it wrong!

As for the modified IS or any car in reality that's a completely different story. Calibrating the chassis leans toward tyre saturation limits and this in turn depends on suspension, bushing compliance with a mix of duty, this being the expected role for the car?

The hardest thing to calibrate in my opinion is you :o ..... Now the car is low with coilovers fitted and the desire is fast, flat high speed cornering..... Well how fast? How flat? How planted do you want the car, do you want to read/ feel the saturation or snap oversteer?

Getting this information is difficult but essential otherwise one owner could say the car is un-drivable and the next driver love it.The reason for this is the human and the car chassis has a frequency, lets say a manufactured easy level that's easy for us mire mortals to drive. Modify the car then everything changes, either the human frequency ( input ) or the cars reaction, both ways there's a telling factor the geometry calibration needs to address if only to dumb the cars frequency down.

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Maybe this simple paper i wrote might help in what shouldn't be a gray area "geometry".....

What is it?
Simply put Geometry is the
X,Y,Z axis that forms a dynamic realm expressed by the suspension,
steering and the cars parallelograms.

Why have it?
The actual tyre contact patch is about 1/3 of the total tyre width. During
the suspensions transitions there is a need to maintain the position of
the contact patch without distortion or saturation but still allow for
comfort and indeed tyre preservation.

How?
Geometry has two areas that concern us after the mechanical engineers offer the final product.
Static:- This is the inert position of X,Y,Z measured during a calibration.
Dynamic:- This is the "expected" gains of X,Y,Z whilst in motion.

The true realm of Geometry is dynamic, a fluid 3D environment applying
Geometric forces that are dependable during Yaw, maintaining the contact
patch..... The holey grail of chassis calibration is realizing the
gains whilst the cars chassis is static... Not an easy task.

The angles and forces
Of the many angles we will just concentrate on three.

Camber:-
Is the vertical position of the wheel, it's duty is to position the
cars weight to the correct area of the tyre contact patch. If the
vertical position is incorrect then the vehicular weight will be
disproportionate and accelerate tyre wear.

Camber force:-
The tilt of the camber deforms the circumference of the tyre sidewall,
this forces the tyre into a conical profile that wants to roll into it's
conical centre...... So if i were to describe the camber force it would
be "compressive".

Toe:-

Is the longitudinal position of the tyre relative to the direction of travel.
In a straight line a need to calculate the type of momentum albeit
front-rear or four wheel drive -V- the actual rolling resistance
generated between the tyre contact patch and the road makes Toe an
infinitesimally difficult position to exact outside of the
theoretical.... Nevertheless the ultimate aim for all drives is a
dynamic 0 toe.

Toe force:-

Toe exerts no force unless aggressively displaced, then the car will feel
unstable off the bump.... Toe cannot make a car pull.

Castor
Is an extension of the front wheels steer axis... By design the lower
steer axis is off-set to the wheel centre and the upper rotational axis.

If an imaginary line was drawn through the pivotal points it would fall in
front of the tyre this is called the "trial distance", by design the
tyre has no option other then to follow the trail unless interrupted by
Yaw.

Castor force:-

Is compressive adding weight to the steering feel.... My best description is the
castors energy is gyroscopic resiting any attempts to deviate from dead
ahead.

Time to turn
Now we have a basic understanding of the angles lets see what happens when you
turn....This explanation will not include inertia or transfer
properties.

Example taken at the front wheels on a 10 degree right lock
At 10 degrees the front camber positions will change from / \ to / / the
near side castor will reduce and the offside will extend.

This action lowers the cars upper parallelogram on the offside corner,
diagonally modifying the camber contact patch, the castor trail and the
acceptance of toe on the inner wheel.

Most believe the recovery of the lock is due to the castor extension or gyroscopic laws, in fact this is not true?

During any lock transition the cars upper parallelogram is supported by the
lower King-pins (lower swivels) as the inner castor sweeps forward the
inclination of the king-pins is off-set so that the inner offside front
is more vertical than the relaxed nearside front.

Since the position of the king-pin is perpendicular a higher position holds more
vehicular weight and since the kingpins are connected via the steering
rack a natural equilibrium insists the steering will be returned.

Those settings
All manufacturers offer a static setting range, this allows for wear since
the driven car is subject to road trauma and progressive deterioration
of the suspension, so we have a range.

On a fully adjustable chassis a range means nothing... Optimum positions can be achieved and
you should expect nothing less if you want to experience the true
splendor of the chassis.

That's it..... I hope my explanation made some sense and offers a little understanding for you and what to
expect at the shop from the Geometry calibration.

Thank you
Tony

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