High Speed Stability

[Gurj Mann]

hello peeps i was in need of some help. i have an is200 sport wich is very "twitchy" at high speed. nothing is loose or worn out,is this the way the car is set up at the factory? how could i help it be more stable, strut brace perhaps?

any ideas appiciated

cheers

[elexes]

get low

harder suspension

if you do that you shouldnt have probloms with high speeds .

or is it cornering your finding probloms with ?

[P38Aaron]

Get a geo check done.

Got mine done today, Tony at Wheels in motion.

http://www.wheels-inmotion.co.uk/

otherwise are you tyre pressures good? what type of tyres are you using and also stupid question, if directionals are they on the right direction?

What are you doing thats making it so unstable at high speed? what is your idea of high speed and type of road?

[VVProtocolVV]

I wish i could get the geo on my lexus checked out as the last time i changed tyres all round the inner section was like bold and the outside tread was still on 2-3mm. I would have to travel aprox 113.25 miles to get to wheels in motion....too far. To make thing worse, when i bought my car from lexus one of the tyre had the rotation wrong?!?! only knew this when i took it to kwit fit (i know they are cowboys, but i had no choice as i was using one of my spare perfect condition alloy/wheel to get to and from work through countrysides). My car at the moment feels sluggish..

[WylieCoyote]

Go and see Dr Bones at wheels in motion. Once the the geometry is set properly the car is much more planted at high speed. Best money you can spend on your car by miles.

Keith

[DJ Wozza]

Here Here !

Go see the Doctor if yor car feels unwell on the handling front !

I live in Kent and made the trip and will be doing the trip again

for my FREE geometry check/adjust after 2000 miles from first adjustment.

(all the effort is well worth it, a 5 min drive in the car after is like a revelation)

I have nothing to gain, just passing on what everyone else says about

their IS200/IS300 after a visit to The Dr.

[Tony-Bones]

hello peeps i was in need of some help. i have an is200 sport wich is very "twitchy" at high speed. nothing is loose or worn out,is this the way the car is set up at the factory? how could i help it be more stable, strut brace perhaps?

any ideas appiciated

cheers

The IS has the ability to handle very well but historically possesses an unstable chassis in particular the front camber positions.

As the camber creeps toward the negative it also reduces the castor angle which is vital for high speed stability. Here is an explanation taken from wim-web.

.................................................

Tilt State Phenomena

In the chapter dealing with the camber angle of the wheels, it can be seen that the camber angle varies according to the positioning or length of the steering arms under the effect of the compression and release of the suspension,

This effect is very useful when steering around bends, when the centrifugal force deforming the parallelograms formed by the suspension units gives the outer wheel on a bend a negative camber and the inner wheel a positive camber,

The same result is obtained on the wheels with the castor angle, but this is generated on the basis of the steering width and the vertical movement of the suspension arms, so the following conclusions can be drawn: when the wheel turns about a kingpin with a positive caster angle, if it is in the outer position on a bend it will take on a negative camber that increases with the strength of the steering action, and will thus act against the overturning of the vehicle, if on the other hand, it is in the inner position on the bend it will take on a positive camber which follows and assists the turn,

Consequently, when the vehicle takes a wide bend (small steering action) at a very high speed, it will be the same centrifugal force which, by acting on the deformability of the suspension parallelograms, will create the advantageous position for the wheels: however, when the bend taken is very tight (strong steering action) and the speed is moderate, it will be the castor angle that will create the advantageous wheel camber angle,

Other factors influencing the castor angle, low-pressure tyres, in modern vehicles, contribute to reducing the castor angle given to the kingpin during construction, in fact, when under the influence of active or braking thrust, the tyres deform and tend to increase the longitudinal offset by shifting their point of contact with the ground,

The castor angle also varies with the variation in the weight distribution of the vehicle, If the load is shifted to the rear axis this will increase the positive castor angle, and if it is shifted to the front axis it will decrease it,

True vertical Kingpin axis extension

Theoretical pivot point

Trail distance

Longitudinal castor angle/ set as positive, the kingpin axis falls in front of the theoretical pivot point generating the trail distance, this gyroscopic affect guarantees stability, and can be defined as the castor angle.

..........................................

Hope this helps.

[Gurj Mann]

the tyres on the front are bridgestone and ray yokohama (now eva its spelt) ive had the geometry done, 4 wheel alignment £40. the tyres are in the proper direction,

on motorways it feels twitchy, (at 3rd lane speeds!), also feels difficult to turn round bends and changing lane unless the speed is dropped to first lane speeds. the car also seems to follow every bump in the road at 30mph.

[Rikos]

Something's not quite right, mine is fine at motorway speeds and i dont have to slow down to change lanes.

When you say you've had the geometry done do you mean the proper geometry or just the laser allignment for £40?

[Gurj Mann]

Something's not quite right, mine is fine at motorway speeds and i dont have to slow down to change lanes.

im getting the oil changed soon at a local garage, will ask them to check over the suspension bushes etc just to be 100%sure.

[Gurj Mann]

laser alignment, adjusted all 4 wheels on camber and toe in and out. have a print out from before and after and it was way from perfect. the machine dials registration and brings up the manufactures settings

[Rikos]

laser alignment, adjusted all 4 wheels on camber and toe in and out. have a print out from before and after and it was way from perfect. the machine dials registration and brings up the manufactures settings

The manufacturers settings are wrong.

Due to foreign parts used, the only way your camber angles will be correct are if you go for a full geometry set up which is around £100. I would strongly recommend getting it done and you'll feel a huge difference.

[DJ Wozza]

Go see the "The geometry Guru D.r Tony Bones".

I had mine for 1 month after I bought it froma Lexus Dealer,

result being...2 nearly new tyres ******* after 1,200 miles, inside edges nearly

bald, they had to put 2 new front tyres on mine and did a 2 hour geometry set up

on the whole car.

After 9 months on

fronts showing bad wear again from inside(but obviously to a much less marked extent)

so I go to see The Dr. It was set up quite well by Lexus, but I was showed where it was still

out, hence the un-even tyre wear. I'm sure your garage did a good job, but the info they have to set

up your car is wrong.... I know not of 1 single LOC member that has been to see Tony that

has not come back a happy man. Also you get a FREE check after 2000 miles to be sure all

is still set as it should be..

It really is worth the trip, especially as the cost of tyres for the Lex ain't cheap.

Now that reminds me my 2000 miles is nearly up !!

Click HERE to talk to The Dr.

Edited July 26, 2007 by Bazza
attempting to use naughty words !

[Tony-Bones]

laser alignment, adjusted all 4 wheels on camber and toe in and out. have a print out from before and after and it was way from perfect. the machine dials registration and brings up the manufactures settings

Can you type the after positions for the camber and castor please.

[P38Aaron]

Lexus's geo settings are wrong. (agreed with Reeko)

Go see the Doc. (wheels in motion)

[Gurj Mann]

ive had the alignment re-checkd and, and it has the same readings as the day i had it done. think the problem is because i had two new tyres on the back, and moved the back to the front axel.

when the alignment was done the back wheels needed adjusting (which now had the fresh set).

and noticed that both front wheels (which were on the back) are worn on the inside. from the inner edge to the first groove.

i am being told that if the rear needed doing then the tyres were out of shape in the first place. moving them to the front axel has exagerated the wear.

this is prob y it is twitch at high speed because the inner part of the wheels are worn.

hope this all makes sense as it took me a while (with the guy using his feet and arms/hands) to make sense of it.

will have to get new tyres, got yokohama ones on rear, 72 each. will get a matching 2 more

[Gurj Mann]

sorry the figures are

left front right front

toe 0`02' toe 0`02'

caster 6`19' caster -0`24'

camber -0`27' camber -0`24'

final toe 0`05'

rear

camber -0`15' camber -0`17'

toe 0`07' toe 0`17'

thrust angle 0`02'

the ` represents a small .o. icon which i aint got on keyboard

[Tony-Bones]

sorry the figures are

left front right front

toe 0`02' toe 0`02'

caster 6`19' caster -0`24'

camber -0`27' camber -0`24'

final toe 0`05'

rear

camber -0`15' camber -0`17'

toe 0`07' toe 0`17'

thrust angle 0`02'

the ` represents a small .o. icon which i aint got on keyboard

I assume the right front castor is 6d 24'... that's good.

Is your car a 99 model?

[Gurj Mann]

the right castor is 7` 04' sorry i didnt c the mistake

its a 200 w(with the cd changer at the bottom of the deck) sport