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Hi Lexus club! I have just aquired a GS300 SE (2001) having been driving those German vehicles for some time!!. Like the Lexus a lot!!
However The vehicle wonders when driving over slightly bumpy surfice and requires continuous checking at the steering wheel. I have checked there is no play in the steering rack and tyre wear looks faily even.
Has anyone experienced this problem and is there a fix. Thanks. Happy New Year.

The good Dr Bones will probably be along later, he might be able to throw some good advice your way

New Years Ev..... larger glasses on so bare/bear? (whatever) with me

Established members will click out now... because the following text becomes a boring repetitive read...... but very important to 'YOU'

If as you say all the mechanical issues have been tested then you are very much in my area, and this is why?..............

The condition of the geometry is very finely tuned between a balance of positions and their respected forces, the GS300 has an adjustable geometry simply because it's expected to move over time, if your cars geometry has violated the factory set-up then the dominant angle/force will permit the sort of problem you describe.

There has been many threads on this topic in 'wheels and tyres' here, this may be of comfort to you that you are not alone....

If you want to 'swat-up' click on the 'wheel-inmotion' banner below and have a gentle read at your leisure, 'IT'S FREE'

If all fails i will help you....1.2.1...... but you must keep team LOC informed with the progress..... 'no one hit wonders allowed!'

Thanks for the advice re Geometry. Have had this checked using laser system. Minor adjustment needed. However the problem is still there although I believe it's not as bad??. I am now looking at wheels and tyres. Do you think I should change the wheels round. Diagonally. or look at smaller wheels. Maybe 16" currently have the 17" with Bridgestone tyres (235/45/ZR17). or change the tyres??

Sadly geometry done does not mean it's OK.... can you post the report here or mail it to me at wheels-inmotion@ntlworld.com and i will check it for you

Ive found on my mk1 the steering abit what id call pointy and id say your driving with just one hand on the wheel,the steering system seems to be very light on the GS even though its speed sensitive.It doesnt seem to weight up like on other cars ive owned as you increase speed with the same sort of speed sensitive system.Ive found two hands on the wheel helps .

Cheers chips.

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Thanks for the advice re Geometry. Have had this checked using laser system. Minor adjustment needed. However the problem is still there although I believe it's not as bad??. I am now looking at wheels and tyres. Do you think I should change the wheels round. Diagonally. or look at smaller wheels. Maybe 16" currently have the 17" with Bridgestone tyres (235/45/ZR17). or change the tyres??
[/quote]

Sadly geometry done does not mean it's OK.... can you post the report here or mail it to me at wheels-inmotion@ntlworld.com and i will check it for you
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I have read the geometry report you sent me and the overall job was well done.......but.

The front Camber has been left at .4' and .7' when the Target is .18'

Historically the GS does not have a repetitive geometry problem so the .18' is a comfortable position, it is not possible or even wise to advise other directions until the Camber position is nearer to the advised position.... and this is why.

Camber is not just an angle it's a force (Horizontally Conical) .... picture this as a negative nsf wheel O> , this lean will ensure the front wheels stay 'compressed' and deliver directional stability.....
Also
The suspension is perpetually active and the arc of the suspension inevitably changes the cambers position, so it can be assumed the forces offered also will change (and it does)
So
To control the addition/subtraction of this force the King Pin Inclination (kpi) will swap it's value..... the kpi opposites the camber and lifts the vehicle slightly on the active wheel.... in doing so the weight of the vehicle pushing back down retains directional control.
To conclude
Since you camber position is near to zero the release of the suspension (off the bump).... 'even a slight one'.. the kpi will decline (lower) the vehicle.... now without the body weight acting on the steering then it's free to wander with the gift of rolling resistance acting on the tyre from the road..... and since the cars momentum is forward this 'free gift' will toe the wheel out (negative) and steer.

[quote name='wheels-inmotion.co.uk' date='Jan 12 2006, 09:06 PM' post='321186']
[/quote]
Thanks for the advice re Geometry. Have had this checked using laser system. Minor adjustment needed. However the problem is still there although I believe it's not as bad??. I am now looking at wheels and tyres. Do you think I should change the wheels round. Diagonally. or look at smaller wheels. Maybe 16" currently have the 17" with Bridgestone tyres (235/45/ZR17). or change the tyres??
[/quote]

Sadly geometry done does not mean it's OK.... can you post the report here or mail it to me at wheels-inmotion@ntlworld.com and i will check it for you
[/quote]
I have read the geometry report you sent me and the overall job was well done.......but.

The front Camber has been left at .4' and .7' when the Target is .18'

Historically the GS does not have a repetitive geometry problem so the .18' is a comfortable position, it is not possible or even wise to advise other directions until the Camber position is nearer to the advised position.... and this is why.

Camber is not just an angle it's a force (Horizontally Conical) .... picture this as a negative nsf wheel O> , this lean will ensure the front wheels stay 'compressed' and deliver directional stability.....
Also
The suspension is perpetually active and the arc of the suspension inevitably changes the cambers position, so it can be assumed the forces offered also will change (and it does)
So
To control the addition/subtraction of this force the King Pin Inclination (kpi) will swap it's value..... the kpi opposites the camber and lifts the vehicle slightly on the active wheel.... in doing so the weight of the vehicle pushing back down retains directional control.
To conclude
Since you camber position is near to zero the release of the suspension (off the bump).... 'even a slight one'.. the kpi will decline (lower) the vehicle.... now without the body weight acting on the steering then it's free to wander with the gift of rolling resistance acting on the tyre from the road..... and since the cars momentum is forward this 'free gift' will toe the wheel out (negative) and steer.
[/quote]
Hi Mr Bones. Thanks for your observations regarding the Geometry report. If, as you say there is still a problem with the settings I need to pop over and visit you in Watford to have it checked. Then we may get somewher before we try anything else. been away hence the delay in reply. will E-Mail you about my visit. Cheers. MIke.(Blomfield)