Steering Vague And Twitchy At Speed

[RichardMD]

Hi,

I have an Is200 (99 model). I have basically had a couple of symptons and wonder if anyone can point to the possible problem. At some point the car developed a steering judder under braking at around 70. Since then ive had 4 new michelin tyres and had it tracked up (cheap kwik fit job). They said it was 3mm out. The car seemed to have improved, partly because of the better tyres. The judder is much less noticeable.

The car had new discs etc and i believe they are ok. Stops well. No judder on the brake pedal.

The other problem which may be linked is a vagueness in the steering at approx mway speeds and slightly above. The steering feels light and quite twitchy. This is quite unnerving.

I considered bushes etc but had an MOT today and it passed with no issues. The mechanic said everything including suspension, bushes, calipers etc were all fine.

Could this be a geometry issue? any opinions?

Many thanks

Richard

[winnie]

Sounds like a Geo prob....get in touch with the Dr at WIM. :D

[RichardMD]

Thks. not been on for a while....is that a user?

[aido]

Tony has a website called www.wheels-inmotion.co.uk - he can advise you or you could pop to either see him or one of his recommended centres - I think the nearest to you would be Drury Lane in Manchester - Tony himself is fantastic but is based in Watford I think so may be a long journey!

Tony gave me some settings which I got a local place to apply and it worked wonders for the car itself!

There are probably some good places near you that do a full geometry, probably worth calling around the ones in the Yellow Pages, ask them if they do camber and toe etc as you want everything aligning really.

[RichardMD]

Thanks. Sounds like Nottingham Car 4 Wheel Alignment is the best local option.

It my be useful to get some alignment settings/recomendations from LOC. My main concern is even tyre wear with having expensive 18" Michelins (and confidence in the handling!!)

Can anyone suggest a setup? Most of my driving is motorway driving.

Thanks for the responses.

[winnie]

http://www.wheels-inmotion.co.uk/forum/index.php?act=idx

[aido]

Tony is definitely the man to speak to - the standard manufacturer approved settings can be found in the knowledge base on this site but Tony found them to be flawed.

My IS was much better with Tony's settings applied!

Might be worth having a chat with him and seeing if you can come to some sort of arrangement :)

He's a great guy (shameless plug!)

[RichardMD]

Thanks. Im sort of relieved i havent got any serious issues by the sounds of things. Hopefully £50 will sort things and save me tyres changes every 5 minutes!

Will get in touch with WIM.

[Tony-Bones]

Assuming all mechanical requirements have been met then the Geometry is the likely criminal. In your case the castor angle:- http://www.wheels-inmotion.co.uk/longitudinal.htm . Historically the Lexus will lose the front camber position over time, this will displace the toe..... when this is corrected the new toe position will rotate the position of the castor angle and lower it. One of the duties for the castor is directional stability but since you still have a castor trail then the stability will diminish at the higher end speed range making the car feel nervous.

The problem owners have is that the castor is not directly adjustable but it is indirectly :D also wim did go public with the positions some years ago and they are here in LOC's knowledge base... Although you will need a competent centre to asses the end results.

[RichardMD]

Thanks. Thats exactly it. Quite scary at speed but reasonably solid pottering around. The MOT chap seemed quite enthusiastaic in telling me all suspension and brake components were ok. I paid kwik fit for a track and all ive got was a misaligned steering wheel for my trouble!

Is there a link to some desired geo settings? If i was able to get these settings implemented would these be suitable for the lifetime of the tyres or would they need regular tweaking? Obviously waying up the trade off off premature tyre wear and alignment costs.

Thanks for the information. Id be happy to come to you but for the fact i live in the midlands! Notts 4 wheel alignment look competant. Maybe worth a go.

Cheers

Rich

Assuming all mechanical requirements have been met then the Geometry is the likely criminal. In your case the castor angle:- http://www.wheels-inmotion.co.uk/longitudinal.htm . Historically the Lexus will lose the front camber position over time, this will displace the toe..... when this is corrected the new toe position will rotate the position of the castor angle and lower it. One of the duties for the castor is directional stability but since you still have a castor trail then the stability will diminish at the higher end speed range making the car feel nervous.

The problem owners have is that the castor is not directly adjustable but it is indirectly :D also wim did go public with the positions some years ago and they are here in LOC's knowledge base... Although you will need a competent centre to asses the end results.

[IS300]

Just want to say a big thanks to Tony at W.I.M. for sorting out my IS300 this week.

It was last tracked 6 months ago at my local Lexus garage but they couldn't sort out the cars nervousness. Read several threads about W.I.M. and decided to give it a go, Tony did a great job and you receive a more personal 1-to-1 service which helps when you have particular issue with the cars driving.

There's also a FREE re-test after 2000 miles to check everythings okay.

I will go there in future for my wheel alignments and shall recommend anyone who's experiencing handling problems with their car. :)

[RichardMD]

Thanks for the PM tony. Booked in saturday at notts 4 wheel. Hope this sorts the issue.

[Tony-Bones]

Thanks for the PM tony. Booked in saturday at notts 4 wheel. Hope this sorts the issue.

Like i said if there are any concerns contact me you have my number.