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How Bad Is "Memory Steer"?

03/08/2011 4:30 PM

I've got a 2004 Pontiac Grand AM with over 110,000 miles. (Don't laugh, it's paid for.) The vehicle's been make clicking noises and pulling to left for some time now, so I took it to a garage I trust for their take on the situation. They've diagnosed the problem as something called "memory steer". Here's how it works. When you make a sharp left turn, the car continues to pull to the left for a bit. The problem is some worn bearings, but the solution requires at least a few hundred dollars worth of work.

Has anyone out there driven a vehicle with "memory steer" for a few months and, hopefully, avoided problems more serious than being annoyed? I've been advised that this is not a safety issue (at least not yet), but I'd sure like to hold onto this vehicle until spring comes and I can get my other ride on the road. At that point, I can think about making the Pontiac's problems someone else's, too.

Let me put my question another way. Should I be more concerned than I am about "memory steer"?

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#1

Re: How Bad Is "Memory Steer"?

03/08/2011 4:53 PM

This should give you the answers that you are looking for by the symptoms.

STEADY PULL

This is a condition where the vehicle continually pulls or drifts to one side while traveling straight. The driver typically has to maintain steady pressure on the steering wheel to keep the vehicle on the road. Possible causes include:

Uneven camber side-to-side. Too much cross-camber can make a vehicle pull or lead towards the side that has the most (positive) camber or away from the side that has the least (negative) camber. The underlying cause may be a bent strut or mislocated strut tower, a bent spindle, collapsed control arm bushing, weak or broken spring, or a shifted crossmember or engine cradle. Check SAI and the included angle to see if these are in or out of specs to diagnose the problem. Also check ride height. Correct by replacing worn or damaged parts, correcting location of strut tower, repositioning engine cradle, and/or reducing cross-camber to half a degree or less by readjusting camber to specifications.

Uneven caster side-to-side. Too much cross-caster can make a vehicle pull or lead towards the side that has the least (negative) caster. The underlying cause may be a bent strut, spindle or mislocated strut tower. Correct by replacing damaged part, correcting location of strut tower, and/or reducing cross-caster to half a degree or less by resetting caster to specifications.

Rear axle steer. The front wheels are with alignment specifications but the vehicle pulls to one side. The underlying cause may be rear toe out of specifications, a bent rear axle, chassis misalignment or a stackup of assembly tolerances in the chassis causing rear axle misalignment. Measure and compare the wheelbase on both sides, check for the presence of a thrust angle, and/or measure individual rear toe. Correct by realigning the rear axle or rear toe, or by performing a thrust angle alignment.

Brake drag. The pull is constant to one side and may get worse with the application of the brakes. Raise the vehicle and spin each wheel by hand to check for excessive drag. Possible causes include caliper sticking, frozen or sticking piston in caliper, overfilled fluid reservoir in master cylinder (does not allow caliper pistons to retract when brakes are released), weak drum brake return springs, misadjusted drum brakes, misadjusted parking brake, misadjusted parking brake pedal switch (creates residual pressure in the master cylinder to cause drag). Readjust or repair brakes as required.

NOTE: If the pull only occurs when the brakes are applied, the problem may be unequal braking not a dragging caliper or misalignment. The vehicle will pull towards the side with the stronger front brake and away from the side with the weaker or inoperative front brake. Uneven braking can be caused by a sticking floating caliper, a frozen caliper piston, the use of different grades or brands of brake linings side-to-side, fluid leaks, or contaminated linings on one side (by brake fluid or grease). Correct by repairing brakes as required. Other causes may include worn or loose control arm bushings or strut rod bushings that allow alignment changes when braking, so be sure to inspect these components before blaming the brakes.

Low tire pressure. The vehicle will lead towards the side with low pressure in the front tire. Correct by inflating tires to recommended pressure.

Mismatched tires side-to-side. The vehicle will pull or lead towards the side that offers the greatest rolling resistance. Compare tire sizes, tread wear, tread styles and patterns, also brands.

Uneven tire wear. If one side of the tread is worn more than the other, the tire develops conicity. The effect is much the same as camber, causing the tire to roll towards the side which is worn most. The uneven wear may be the result of incorrect camber, toe and/or failure to rotate the tires periodically to even out wear. If rotating the tires side-to-side reverses the direction of the pull, the tires need to be replaced.

Ply steer. A manufacturing defect in the way the belts are positioned inside the tire causes the tire to generate a lateral (sideways) force as the tire rolls. To test for this condition, drive the vehicle forward, then in reverse. If the direction of the drift or pull changes, one or more tires at at fault. Rotating the tires front-to-rear or crosswise may help cancel out the ply steer, otherwise tire replacement is necessary to correct the condition.

Memory steer (see memory steer).

Unbalanced power assist. Seal leaks in the control valve or off-center steering may route hydraulic pressure into one side or the other of the boost cylinder piston causing the steering to want to turn itself to one side. This can be checked by raising the wheels with the engine running to see if the wheels turn to one side by themselves. No change would indicate another cause, but if the pull suddenly vanishes an imbalance in the power steering system is to blame. The control valve assembly or steering gear needs to be replaced.

Excessive road crown. Roads are raised or crowned in the middle so rain water will run off to the outside for proper drainage. But the slight slope to the pavement can often make a vehicle drift to the outside. This can be countered by adding a little positive camber and/or negative caster to the left front wheel , but this should only be done if the vehicle spends most of its time on crowned roads and you have a noticeable pull.

MEMORY STEER
The steering wheel and wheels want to return to some position other than center. This may cause a steering pull or drift to one side after turning. Possible causes include:

Misalignment or improper installation of Ford rubber bonded socket (RBS) tie rod ends. RBS tie rod ends do not swivel freely like conventional tie rod ends. When installed, the steering linkage must be centered and straight ahead before the tie rod studs are tightened. Inspect and readjust as needed.

Binding in upper strut mounts. Raise wheels and turn the steering from side to side. If effort is high, disconnect tie rod ends from steering arms and turn each wheel by hand to check for resistance. If upper strut mount is binding or loose, the strut will have to removed or rebuilt to replace the upper bearing plate assembly.

Binding in steering gear or linkage. Inspect tie rod ends and sockets. Check idler arm bushing. Check rack yoke adjustment or steering play in steering box. Replace or adjust as needed.

Binding in ball joints. Unload the ball joints by raising the suspension. Let the suspension hang free with MacPherson struts. Support the lower control arm on an SLA, modified strut or wishbone suspension if the spring is on the lower arm, or the upper arm if the spring is over the upper arm). Turn the wheels from side to side to check steering effort. If high, disconnect the tie rod ends and try again. If a ball joint is binding, replacement is required.

Unbalanced power assist. Seal leaks in the control valve or off-center steering may route hydraulic pressure into one side or the other of the boost cylinder piston causing the steering to want to turn itself to one side. This can be checked by raising the wheels with the engine running. If the steering goes to one side all by itself, the control valve assembly or steering gear needs to be replaced.

OFF-CENTER STEERING WHEEL
This condition may accompany a steady pull or memory steer. But if the steering wheel is off-center (crooked) but there is no pull to either side, possible causes include:

Steering linkage not centered when toe was adjusted. Correct by recentering steering wheel and equalizing lengths of both tie rods, then readjusting toe to specifications.

Bent steering arm or linkage. Check turning angle both ways. If arm is bent, knuckle (or strut if arm is attached to strut) will have to be replaced.


STEERING WANDER

The vehicle lacks directional stability and wanders or drifts from side to side. Possible causes include:

Loose or worn steering components. Inspect the tie rod ends, inner tie rod sockets on rack & pinion steering units, and the idler arm and center link on parallelogram steering. Check the steering column couplings. Also check for loose or broken rack mounts. Check the amount of play in the steering rack or steering gear. Lateral play at the edge of the steering wheel should usually be less than 1/4 inch (always refer to manufacturer specifications). Replace worn parts and/or adjust rack yoke or adjustment screw on steering box to reduce play.

Loose or improperly adjusted wheel bearings. Check and adjust wheel bearings to specifications.

Insufficient caster. This may be due to increased ride height at the rear of the vehicle (raising the rear end with air shocks or air springs) or lowered ride height at the front of the vehicle (weak springs or shorter than stock springs). Increase caster and/or reset to specifications.

Extremely low tire pressure. Inflate to recommended pressure.

Extreme toe misalignment. Check the steering linkage and adjust or repair as needed.

BUMP STEER
The steering suddenly jerks or veers to one side or the other when the vehicle passes over a bump. The condition is caused by unequal toe changes that occur as the suspension travels through jounce and rebound. The condition can be confirmed by checking individual front toe with the suspension loaded (compressed), then checking toe again with the suspension raised slightly. If the amount of toe change is not equal on both front wheels, it can cause a momentary pull to one side. The direction of the pull will depend on which end is high or low, and whether the steering linkage is ahead or behind the knuckle.

Possible causes include:

Parallelogram steering linkage not level. Check the idler arm height, and adjust as required.

Steering rack not level. Check rack height and rack mounts. Repair, adjust or replace as needed.

Bent steering arms. Check to see that both are the same height. Replace knuckle (or strut if arms are mounted on strut) if bent to correct.

Structural damage such as frame twist, mislocated or twisted crossmember or engine cradle.

Not centering the steering linkage before adjusting toe. This can result in unequal toe changes when the suspension moves up and down.

TORQUE STEER

The steering veers or pulls to one side during hard acceleration. This is a common condition in front-wheel drive cars with unequal length driveshafts, and is caused by unequal toe changes as the suspension is loaded. Compliance allows the wheel with the longer driveshaft to experience less toe-in change than the wheel with the shorter driveshaft. This causes the vehicle to veer towards the side with the longer driveshaft. FWD cars with equal length driveshafts usually do not experience this condition.

Torque steer cannot be eliminated, but certain conditions may make it worse:

Loose or collapsed control arm bushings.

Loose or worn tie rod ends.

Loose or worn inner tie rod sockets.

Loose or broken engine/transaxle mounts.

Vehicle manufacturers have offered various repairs to reduce the severity of torque steer in some FWD cars. The corrective measures include using stiffer control arm bushings, shimming motor mounts, realigning the engine cradle, replacing the motor mounts with stiffer mounts, or increasing cross-camber.

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#8
In reply to #1

Re: How Bad Is "Memory Steer"?

03/09/2011 11:47 AM

Hello Jspeop. Nice find.

I will help you out with the customary credit: AA1CAR.com

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#11
In reply to #8

Re: How Bad Is "Memory Steer"?

03/09/2011 2:45 PM

Thanks have been doing work on autos for over 40 years and I just keep studying and writing up info for interns that I take in to try to train in the proper way to diagnose and repair vehicles instead of the common hit and miss parts changer that you find so much today in the dealer and repair facilities. Thanks again.

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#2

Re: How Bad Is "Memory Steer"?

03/08/2011 5:07 PM

I've made it home from some bars on "memory steer",in my misspent youth, but this needs to be fixed. Someday, you may not be able to correct the steering.

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#4
In reply to #2

Re: How Bad Is "Memory Steer"?

03/09/2011 12:09 AM

After a gig one night back in 1976, I made it home. Dam car steered me away from my exit, ended up making a U turn after the Castelton Bridge first brake, finally got home. Fell on the sidewalk, crawled into the house, crawled onto the bed, jumped off, fell on floor after bouncing off fridge, back on floor and proceeded to toilet for many hours.

After that every time we played Charlie Daniels, I stayed away from Old #7 as we did Whiskey and passed the 2 bottles around us and the crowd. And even today, I can not look at a bottle of old #7. My fingers were bleeding, I soaked them in #7, and drank like a sailor. All 10 finders were bleeding that night. I am , was, a Bass Player. Gave that up in 1973 for a real job. I still play for myself. My wife just bought me a new amp, so who knows where that will lead. I do know one thing, No recording studio's and them people. Screw their 5 year world tours. Loved the bars scene, they paid well, studios, and them folks had nothing to offer but smack and paid zip. Now, engineering an aquacultural center fish farm, Nation wide! And still playing Bass for myself! With a new Amp that kicks A$$!! Thanks to my wife. (Left my Cerwin Vega) with a friend in 1995.

He disappeared with it soon after. Hope he enjoyed it like I did.

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#3

Re: How Bad Is "Memory Steer"?

03/08/2011 11:55 PM

Pontiacs are famous for their clicking steering shafts. It was extremely prevalent in the Bonnevilles (2000 and newer), which shared the shaft with Cadillac as well. Replacement of the intermediate shaft may be in order. You can also fill the boot using a small grease injector, working it side to side to distribute the grease as you go. I had three Bonneys, all with the same problem.

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#5
In reply to #3

Re: How Bad Is "Memory Steer"?

03/09/2011 10:01 AM

Thank you, I have a 2005 Bonneville I bought used and the clicking is there. No independent garage has been able to find the problem and dealer told me not to be too concerned.

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#9
In reply to #5

Re: How Bad Is "Memory Steer"?

03/09/2011 12:15 PM

General Motors actually bought my second Bonneville back from me, and gave me $6,000 towards the purchase of my third. I went from the SSEi to the GXP. The shop (a GM dealership) couldn't figure out theirs heads from a hole in the ground, to put it lightly. I went so far as to put a video camera in the car to see what they were doing wrong. I went through a lot of trouble and an arbitration process using the BBB and the state's attorney general office.

As I said before, the intermediate shaft is a known issue which would create or augment what is being referred to as memory steer. My wife had a near accident and ended up running off of the road because the steering locked up, then memory steered into a parking lot from a four lane road. Big fun.

There are a couple of technical service bulletins (TSB's) on the issue. If you can find those they describe the issue and what GM recommended for a fix. I'll see if I can find some info in my records.

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#6

Re: How Bad Is "Memory Steer"?

03/09/2011 10:18 AM

The clicking when in a tight turn is usually due to worn-out Constant-Velocity (CV) joints in the prop shafts. These are the universal joints in the prop shafts that flex when the front wheels steer. They are covered with accordian-style rubber bellows to keep dirt out. The bellows tear and allow dirt to enter the joints, causing them wear out.

You say that when you make a sharp turn to the left, the car continues to pull to the left for a bit. Do you mean the steering wheel does not return to center on its own, or do you mean that after returning to center, there is still a pull to the right?

A worn wheel bearing will not hold the wheel in is proper position, and can cause the pull you mention. Good quality replacement wheel bearing assemblies are available for under $100 US. Here is a link to brief description of what it takes to replace the wheel bearing assembly. Also, the wheel bearing assembly has to be removed in order to pull the prop shaft for repair or replacement. Remanufactured shaft assemblies run $50-$80 US. It is also a good time to have the front brakes redone, since they have to be pulled.

So, you are looking at a couple hundred in parts and about an hour labor, per side (there is a bearing and shaft for each front wheel), plus $10 to turn each brake rotor, plus a front-end alignment. You will probaly see an improvement fuel economy and a reduction in tire wear.

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#7

Re: How Bad Is "Memory Steer"?

03/09/2011 11:35 AM

The problem you have is a bad CV half shaft. This is a front wheel drive car and uses a constant velocity joint on the front drive shafts or half shafts. Most likely you heard a clicking start when you turned corners and as time went on you are most likely hearing the clicking all the time. Once the clicking starts they wear rather quickly because metal filings are getting into the grease and increasing the wear. The car pulls to the left because there is increased drag on the left side due to the CV binding. It will eventual fail and you will blow the half shaft. If you mechanic is quoting memory steer you may have other worn parts in the steering such as bad ball joints or tie rods ends. I would address the CV issue or it may leave you stranded with a large towing bill besides the cost of the repair.

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#10
In reply to #7

Re: How Bad Is "Memory Steer"?

03/09/2011 12:36 PM

I know what you are saying with the CV joint, and that may be what he is experiencing. Since he said it was an '05 Pontiac, I thought he may have been referring to the intermediate shaft. The driver can feel this with the engine running and the car in park, and then turning the wheel side to side. the steering wheel will transmit the sometimes faint, sometimes obvious, clicking. It is also audible in more advanced cases.

If he is getting this on acceleration with the wheel turned, I would also suspect the CV joints. That's a classic sound which his shop should have been able to diagnose within two seconds.

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#12

Re: How Bad Is "Memory Steer"?

03/09/2011 3:20 PM

Hello Moose. I have had people describe a clicking to me which i thought was a deeper clunking sound in similar vehicles with similar sounding problems.A clicking as posted previously is most likely a steering shaft or constant velocity joint.Steering shaft problems are never something to be ignored.Constant Velocity Joints are similar in a way to ball bearings in that they both use metal balls designed to run in a raceway or simply race.If the races in the outboard cv joints become worn enough it is possible for the metal balls to move slightly in and out of their races causing a clicking sound.This will continue until the metal balls leave the race to where they no longer roll but bind up the outer joint with the axle and find sufficient play between the transaxle and wheel bearing to force apart.There is another sound which i describe more as a lower tone clunk which sometimes includes a short low reverberating sound which originates from the coil springs.This noise is particularly associated with memory steer.When the upper strut bearing plates wear to binding instead of freely moving the turning of the steering causes the coil springs to take the side load and reposition themselves in the strut causing the noise.This horizontal stress/vibration on rusty coil springs occasionally causes them to break and puncture a steering tire.I am sure you can imagine the results depending on speed and location. Good luck.

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#13

Re: How Bad Is "Memory Steer"?

03/11/2011 9:11 AM

Many thanks to all for answering my question! I've learned a lot from you and am now less inclined to just try to limp through March until I can put my Mustang back on the road. That "low clunking" noise that grandpaw describes is also present (and not just the clicking).

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