Steering Problems

[marcus428]

I have a 94 SC 400. I've had the front end aligned and put new BF Goodrich g-force tires on the car but the steering problems won't go away. When changing lanes, the car lurches into the new lane as it passes over the lane divider. And when driving on or coming to a stop on a road with a slight lean to the right, the steering wheel will pull to the right. Yet on a flat road the steering wheel remains straight. Lexus has looked at the front end and so has another mechanic. Both say everything checks out ok. However, they both agree that something is not right. Anybody else ever had a steering problem like this?

Thanks,

[Tony-Bones]

I have a 94 SC 400.  I've had the front end aligned and put new BF Goodrich g-force tires on the car but the steering problems won't go away.  When changing lanes, the car lurches into the new lane as it passes over the lane divider.  And when driving on or coming to a stop on a road with a slight lean to the right, the steering wheel will pull to the right.  Yet on a flat road the steering wheel remains straight.  Lexus has looked at the front end and so has another mechanic.  Both say everything checks out ok.  However, they both agree that something is not right.  Anybody else ever had a steering problem like this?

Thanks,

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You say the "problems wont go away" what happend between the time when thinge were ok and when the problems started?

[marcus428]

I bought the car about 2 months ago and I thought it was a tire related problem. The car had Eagle GT's on the front and Continental's on the rear. I figured a new set of tires would fix the problem; but it didn't.

[eXOBeX]

Had a four-wheel alignment done?

[Tony-Bones]

I bought the car about 2 months ago and I thought it was a tire related problem.  The car had Eagle GT's on the front and Continental's on the rear.  I figured a new set of tires would fix the problem; but it didn't.

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As with all handling problems mechanical wear is the first point of attack, tyre wear next, since both are visible, next must be the geometry! you say you had the alignment done, was that basic alignment or full geometry? if full can you display the readings...

[marcus428]

I had a front end alignment done when I got the tires installed. I took the car back and the mechanic stated the alignment was to specifications. When I drive on a straight flat road the car stays straight but any slope in the road and the car will follow it. It's like the steering is influenced by any changes in the road surface. Even a turning arrow painted on the road surface will cause the wheel to turn. I guess I'll go get a four wheel alignment and see if that fixes it. I've had people also speculate that it could be the shocks, anti-lock brakes, or variable speed power steering (does this car have one?).

[Monster-Mat]

indeed it could be the speed sensitive steering, the speed delimiter/mph/kmh converter could be making it seem like your going slower than you are

thereby lightning up the steering. this is a problem i have heard of before!

does the car have aftermarket wheels

[Monster-Mat]

hmmmm, just seen your in melbourn, so the speed delimiter thing........ignore

[marcus428]

Car has the original wheels, no aftermarkets. Why is the speed delimiter not a possiblity?

[Tony-Bones]

I had a front end alignment done when I got the tires installed.  I took the car back and the mechanic stated the alignment was to specifications.  When I drive on a straight flat road the car stays straight but any slope in the road and the car will follow it.  It's like the steering is influenced by any changes in the road surface.  Even a turning arrow painted on the road surface will cause the wheel to turn.  I guess I'll go get a four wheel alignment and see if that fixes it.  I've had people also speculate that it could be the shocks, anti-lock brakes, or variable speed power steering (does this car have one?).

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If Lexus and the mechanic have checked the car then i think we can assume the shocks/ abs and so on are ok? i feel you must eliminate the geometry, there are so many reasons why the geometry can cause problems like yours i think you need to read for yourself [url=http://wheels-inmotion.co.uk hit the site map and read toe/ camber/ castor/ kpi this may help in advance of your geometry test and its free.

[marcus428]

You were right. It was the 4 wheel alignment. Should have had that done when I bought the new tires. Thanks for your help!

[mrdsukautos]

The following is best for 3. V8GT w/out TEMS. Fitted with 16" rims up to 8" wide front and rear.

Front toe-in Left

MIN. 0.0mm

OPTIMUM 0.3mm

MAX 0.6mm

Front toe-in Right

MIN. 0.0mm

OPTIMUM 0.3mm

MAX 0.6mm

Front toe-in Total

MIN. 0.0mm

OPTIMUM 0.6mm

MAX 1.1mm

Rear toe-in Left

MIN. 1.9mm

OPTIMUM 2.2mm

MAX 2.5mm

Rear toe-in Right

MIN. 1.9mm

OPTIMUM 2.2mm

MAX 2.5mm

Rear toe-in Total

MIN. 3.8mm

OPTIMUM 4.3mm

MAX 4.9mm

Camber, Now this is very important! When you go to your tyre place they may tell you to have only what the 'Book' says, IGNORE THEM, the following has been obtained at great time and expense to me, and the 'Book' settings are for the Asphalt in Japan and are not the best for this Country.

Front each side. Neg. 0 deg. 10 min. ± 10 min.

Rear each side. Neg. 0 deg. 40 min. ±10 min.

The small tolerance will be a 'contentious' moment for you and the setter may baulk at this accuracy, but keep insisting, on the road the car feels much more stable.

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The following is best for 4. V8GT with TEMS. Fitted with 17" rims up to 8" wide front and 9½" rear.

Front toe-in Left

MIN. 0.0mm

OPTIMUM 0.3mm

MAX 0.6mm

Front toe-in Right

MIN. 0.0mm

OPTIMUM 0.3mm

MAX 0.6mm

Front toe-in Total

MIN. 0.0mm

OPTIMUM 0.6mm

MAX 1.1mm

Rear toe-in Left

MIN. 1.9mm

OPTIMUM 2.2mm

MAX 2.5mm

Rear toe-in Right

MIN. 1.9mm

OPTIMUM 2.2mm

MAX 2.5mm

Rear toe-in Total

MIN. 3.8mm

OPTIMUM 4.3mm

MAX 4.9mm

Camber, Now this is very important! When you go to your tyre place they may tell you to have only what the 'Book' says, IGNORE THEM, the following has been obtained at great time and expense to me, and the 'Book' settings are for the Asphalt in Japan and are not the best for this Country.

Front each side. Neg. 0 deg. 20 min. ± 10 min.

Rear each side. Neg. 1 deg. 00 min. ±10 min.

The small tolerance will be a 'contentious' moment for you and the setter may baulk at this accuracy, but keep insisting, on the road the car feels much more stable.

Hope the above helps mate. Check the settings are within these tolerances

[harleypeyton]

You were right.  It was the 4 wheel alignment.  Should have had that done when I bought the new tires.  Thanks for your help!

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Just a brief note of gratitude. I've had my SC 430 for three years, and suddenly, last month, it started veering to the right at low speeds, and, as I described it to the Lexus mechanics, felt like the road was driving the car (and not the reverse). They had no idea what I was talking about. The problem persisted to the point where I began to question my own, well, you know, sanity. Then, one lucky google and I found your post. This time the Lexus mechanic, after I read him your emails, seemed surprisingly familiar with the problem (something about tire size, and 'toe out'), and while he was willing to guarantee nothing (thanks a lot), I'm getting the four wheel alignment done tomorrow.

Here's hoping it works.

Thanks again.

[Zee007]

Just a brief note of gratitude. 

Thanks again.

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Ah - isn't it nice when we help people....

I feel all warm and fuzzy...... :D

[marcus428]

The Lexus dealership aligned the car twice but the car still handles weird. It still follows changes in the road and on a windy days it gets pushed all around. The Lexus dealership felt it was better to set the alignment as close as possible to the middle of each spec range and weren't sure if the settings you provided from England would work in the US. Do you know if there are optimum settings for this country (US)? Here are the settings I currently have (in degrees): Left Front Camber 0.1, Right Front Camber -0.1, Left Front Caster 2.7, Right Front Caster 3.2, Left Front Toe 0.05, Right Front Toe 0.04, Left Front SAI 8.4, Right Front SAI 8.8, Left Front Included Angle 8.5, Right Front Included Angle 8.7, Front Cross Camber 0.1, Cross Caster -0.5 and Total Toe 0.09. Rear Left Camber -0.9, Rear Right Camber -0.9, Rear Left Toe 0.20, Rear Right Toe 0.20. Rear Total Toe 0.4, and Rear Thrust Angle 0.00.

[Tony-Bones]

The Lexus dealership aligned the car twice but the car still handles weird. It still follows changes in the road and on a windy days it gets pushed all around.  The Lexus dealership felt it was better to set the alignment as close as possible to the middle of each spec range and weren't sure if the settings you provided from England would work in the US. Do you know if there are optimum settings for this country (US)? Here are the settings I currently have (in degrees): Left Front Camber 0.1, Right Front Camber -0.1, Left Front Caster 2.7, Right Front Caster 3.2, Left Front Toe 0.05, Right Front Toe 0.04, Left Front SAI 8.4, Right Front SAI 8.8, Left Front Included Angle 8.5, Right Front Included Angle 8.7, Front Cross Camber 0.1, Cross Caster -0.5 and Total Toe 0.09. Rear Left Camber -0.9, Rear Right Camber -0.9, Rear Left Toe 0.20, Rear Right Toe 0.20. Rear Total Toe 0.4, and Rear Thrust Angle 0.00.

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Nothing wrong with that report :D time to move on... what "actual" tyre size and make do you have, and how is the wear on these tyres.

[marcus428]

The tires are BF Goodrich g-force 225/55/16 (ZR) and I keep them at 38 lbs (any lower pressure and the steering is "mushy". The tires do have an aqua tread center so I am getting some tramling however, the problems are more evident when there is a slight change in elevation of the road (such as a dip or rise or change in the crown of the road).

So far this is what I have recommened from other threads:

LCA Bushings (lots of people think it is this but the mechanic said they checked out ok)

Steering Rack Bushings (mechanic checked this too and said it was ok)

Tires (tramlining)

Alignment (we've been down this road and I can tell that the alignment is out again. What can keep pulling the alignment out?)

Shocks (something about the gas portion of the shocks leaking out)

So what do you think?

Thanks for your help.

[Tony-Bones]

Can you measure the "trim height" thats the height of the body, taken from mid wheel arch to mid wheel across each axle ( nst/ osf, nsr/ osr ) and post them :D