Tight Radius Turning Issue

[C17Jock]

Here's one,

I have a 98 LS 400 and when slowly turning full right out of a stationary position, the car wobbled as if it had a flat tire during the entire 180 degree maneuver. The wobble seemed to coincide with the tire rotation speed. All the tires/wheels looked fine. I was able to partially reproduce the wobble only once. I had the car serviced four weeks prior to the incident and the front end received a Toe alignment. Other than this the car drives smoothly at all speeds. I would greatly appreciate any suggestions. Thanks.

[Ross W.]

Here's one,

I have a 98 LS 400 and when slowly turning full right out of a stationary position, the car wobbled as if it had a flat tire during the entire 180 degree maneuver.

My car does that too sometimes. The balljoints and suspension bushings need to be replaced on my car. With all the stress placed on the front end in that situation, the free play in the balljoints and the slop in the original rubber bushings makes things wiggle around quite a bit. A previous car I owned with a similar front suspension design did the exact same thing, and after the front end was rebuilt, no more wobble!

[C17Jock]

Here's one,

I have a 98 LS 400 and when slowly turning full right out of a stationary position, the car wobbled as if it had a flat tire during the entire 180 degree maneuver.

My car does that too sometimes. The balljoints and suspension bushings need to be replaced on my car. With all the stress placed on the front end in that situation, the free play in the balljoints and the slop in the original rubber bushings makes things wiggle around quite a bit. A previous car I owned with a similar front suspension design did the exact same thing, and after the front end was rebuilt, no more wobble!

Thank you for your insight. Did the front end give any other indications of wear?

[Ross W.]

Thank you for your insight. Did the front end give any other indications of wear?

Yes. The outside edges of the front tires are cupping, which is also an indication. Normally the outside edges of the tires just wear off, but the cupping indicates funky camber changes and oscillations from the worn parts. Soon I'm going to have to get mine done! I've got polyurethane bushings from Daizen, and I'll be getting new ball joints. Winter project! As an aside, the rear suspension needs to be done, and new shocks all around. Depending on the mileage of your car, look into those issues as well.

[wwest]

It seems remote even to me but you may have inadvertently triggered the LSD (Limited Slip Differential) simulation/virtualization aspect of your traction control system, especially if you do not have VSC, but maybe even if you do.

Traction control uses the ABS wheel speed sensors to determine if you are encountering wheelspin/slip due to a slippery surface or too much throttle. In a really tight turn the traction control may get fooled into thinking wheel spin/slip has occurred as a result of the desparate rate at which the rear wheels are turning vs each other and/or vs even the front.

With VSC there is a stearing wheel position sensor and thereby the system can "know" why the rear wheels are turning at a different rate, provided the early versions of VSC foresaw that eventuallity.

[Ross W.]

It seems remote even to me but you may have inadvertently triggered the LSD (Limited Slip Differential) simulation/virtualization aspect of your traction control system, especially if you do not have VSC, but maybe even if you do.

Traction control uses the ABS wheel speed sensors to determine if you are encountering wheelspin/slip due to a slippery surface or too much throttle. In a really tight turn the traction control may get fooled into thinking wheel spin/slip has occurred as a result of the desparate rate at which the rear wheels are turning vs each other and/or vs even the front.

With VSC there is a stearing wheel position sensor and thereby the system can "know" why the rear wheels are turning at a different rate, provided the early versions of VSC foresaw that eventuallity.

That could be a possibility too if the car is equipped thus. I've engaged the limited slip in my car, but it feels and sounds quite different from what's been described. But with the later cars having that done electronically, that could be a different story altogether.

[nc211]

I agree with wwest. My 95 does not have the vsc system, yet if I do a tight U turn on an incline "like pulling out of a parking lot", the car will feel like it's performing a "crab" motion. I though for the longest time something was wrong. But it's just the spinning difference in the rear wheels. The car turns so tightly that your inner rear wheel hardly moves, yet your outter rear wheel is making the entire turn. It makes for a funky feeling. My ball joints, tie rods, control arms, etc.... are all new. In the suspension department, my car is perfect as if it were new. And my car will do this exact same funky feeling in a really tight turn.

It's sort of like turning an old Jeep CJ on dry pavement with the front hub locked into 4x4.

However, you might consider changing out the rear differential fluid if you have not done so in the past 20k miles. Always a good idea to keep those gears well maintained...

[VBdenny]

I know the upper control arms are an issue on older LS400's Lexus wants to sell you the whole control arm but you can buy just the bushing replacements.

[sha4000]

i have this exact same problem from time to time on my 98 also. its not a good feeling and it feels like something is broken but the car drives fine in all other areas