1990 Buick Lesabre steering geometry changes

Tiny
DIETERSCHMIED
  • MEMBER
  • 1990 BUICK LESABRE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 120,000 MILES
Dieter Schmied: I have a 1990 Buick Lesabre that has a steering geometry problem

When I go into a curve the car will lurch and the steering wheel will attain a position that is a few degrees off of what was the straight ahead position. This position will remain until I enter an opposite curve or if I hit a rough spot on the road. This is very consistent. If I were not aware of this change in geometry, the lurch might literally throw me into another lane. I have checked or replaced the hub bearings. I replaced one inner tie rod end. I replaced the struts. I also noted that the camber angle changes between the two settings when I checked it with a spirit level. Also when I enter a curved-to-the-right exit ramp, I sometime get a slight squealing of the front tire. As long as I am on a straight level road, I have no problem and the steering wheel is positioned as it should be. I tried to check for movement of the steering rack, but I was unable to see any movement or signs of movement.

Some immediate thoughts about the symptoms are:

How can I check the lower ball joints?

How can I check the top strut supports under the plastic caps in the inner fender where the strut nut is located?


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Monday, November 15th, 2010 AT 5:05 AM

11 Replies

Tiny
FIXITMR
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To check lower ball joints pull back and forth on front tires by grabbing top edge ther should be no give/play at all.
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Monday, November 15th, 2010 AT 5:18 AM
Tiny
CARADIODOC
  • EXPERT
To elaborate, the jack must not be under the lower control arm. Jack it up by the frame or cross member. You might need a helper to tug on the bottom of the tire while you watch for movement between the ball and socket of the ball joint. Check for up and down movement with a pry bar between the spindle and the lower control arm.

Also check for worn rubber lower control arm bushings and in rare cases a stretched mounting hole in the cross member where the control arm bolts to.

Caradiodoc
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Monday, November 15th, 2010 AT 5:27 AM
Tiny
FIXITMR
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You should also raise front of car slightly and watch steering as someone turns wheel back and forth. Look for any play in joints.
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Monday, November 15th, 2010 AT 5:28 AM
Tiny
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I get no play when grabbing the tire at the top and bottom or when I use a pry bar.
Is there an incorrect way to install the bearing at the top of the strut.
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Monday, November 15th, 2010 AT 6:01 AM
Tiny
FIXITMR
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Are the tries wearing funny? Did you do an rough alignment check with a tape measure?
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Monday, November 15th, 2010 AT 7:11 PM
Tiny
FIXITMR
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If changing struts had no effect on problem I would not suspect strut bearing. The only problem I have sen with them is noise.
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Monday, November 15th, 2010 AT 7:29 PM
Tiny
DIETERSCHMIED
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I have been following all of the suggestions; I have not forgotten you all. It isn't the ball joint and it isn't the strut bearing and I could not find any badly deteriorated rubber bushings. I have been at a handicap because I haven't anyone that I can work with on this that know what to look for when I am behind the wheel. That should change next week.

But I think I have an idea. Could all of this be attributed to motor/transmission mounts? I can't tell if one or more of the mounts are bad by myself and I need someone I can trust to do the foot on the brake and apply the engine torque to lift the engine. I have had a bad experience doing that once in the past with someone who did not know what he should be doing and the car took off knocking me to the ground and was stopped by my BMW.

What do you all think? Motor mounts?
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Wednesday, December 1st, 2010 AT 8:33 PM
Tiny
CARADIODOC
  • EXPERT
Uhmmm. I don't THINK so. Motor mounts shouldn't affect steering wheel position. What they COULD do is lower one side of the engine causing a change in half shaft angle. That can lead to torque steer under acceleration, but that really doesn't fit with your original description of the problem.

How about a loose rack and pinion assembly? What do you think, fixitmr?

Caradiodoc
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Wednesday, December 1st, 2010 AT 8:48 PM
Tiny
DIETERSCHMIED
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I had checked the rack and pinion for movement and for slop and I had replaced one of the inner tie rods because it had some play.

There are only two positions of the steering wheel that shifts. I am able to make it change by making a right hand turn either during acceleration or when the turn exert some g-forces in a longer turn. The steering wheel will turn about five to ten degrees and it will stay so long as I don't turn to the left or I can hit a bump in the road at which time it will "snap" to the straight ahead position.

I have had a problem with intermittent vibration like a wheel out of balance, but replacing the half shaft seemed to arrest that symptom somewhat. That and making a hard right turn under acceleration from a dead start results in a noise like the axle cv joint is in a bind makes me think that the engine is actually shifting.

I ordered all four mounts today. The present mounts are original and at least one is spongy so if it isn't the cause of the problem, it will at least put the engine in alignment with the axles.

I'll let you know what happens.

Is there anything peculiar to the particular model that I should be aware of when replacing the mounts?
Thanks
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Thursday, December 2nd, 2010 AT 3:33 AM
Tiny
CARADIODOC
  • EXPERT
The only thing particular to GM cars is the engine cradle / cross member. It is unbolted and lowered to remove the engine or transmission. It is very important to put it back in exactly the same spot as it was. If it is not, it will change steering axis inclination, (SAI). That is the imaginary line drawn through the upper strut mount and the lower ball joint. Those are the two pivot points for the steering. There is no correct value for that angle. What is critical is they are the same on both sides.

When the cradle is shifted sideways, the lower control arms and ball joints move along with it. That will move the bottoms of both tires to the side so one will be tipped out on top and the other one will be tipped in. Tires want to pull in the direction they are leaning. To fix that pull a hastily-performed alignment will catch the incorrect "camber" values. Camber is the inward or outward tilt of the tire. Even though camber can be corrected to make the tires stand up straight again, the SAI will be different between the two sides. That will make a very unstable handling car over bumpy roads.

Think of a person with one short leg who wears a tall shoe. Sure, they might stand up perfectly straight, but they'll look funny when they try to run. Fixing camber without correcting SAI will make the alignment numbers look good on the alignment rack but it won't address the poor handling on the road.

Caradiodoc
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Thursday, December 2nd, 2010 AT 5:52 AM
Tiny
DIETERSCHMIED
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Final Report!

First of all, thanks for your input.

I bought all four mounts for $52. I had a quote from a Buick dealer for about $150. A piece. It took a few hours, but it should not have. Only one mount was broken and it caused one small clunk but it did not solve the problem. I can feel the engine vibrations better now and I don't know if that can be considered progress.

The noises got worse as I aggravated the problem with some rough maneuvers. I pulled off the right tire and rim assembly and saw a wear line on the inside of the rim and this was progress. The ball joint was rubbing the rim. I still could get no play in the ball joint. I place a block under the ball joint and let the jack down. With the weight of the car on the ball joint bottom, nothing happened. I then decided to turn the steering wheel and then came the "clunk". It was the ball joint!

I was never able to get the movement or play that I think I should have seen.

I have never had much luck in diagnosing ball joint problems. My last ball joint experience was a used Renault that I bought in Hamburg and drove to Berlin the first day that the border was opened after the fall of the wall. It would squeak except when I would drive through a water puddle. I had no tools but I bought the Kugellenker and for three months when I could return to Hamburg, I would seek lubricating water puddles to give me temporary relief from the noise.

Tschuss und Danke!
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Sunday, December 12th, 2010 AT 4:54 AM

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