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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 05-16-2006, 09:35 PM
pmcwhinnie pmcwhinnie is offline
 
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Need help with tire/handling problem

Hi,

I have a 2002 540i/M. Put my summers (SP Sport 2000 Es) back on a few weeks ago and have noticed that (a) I now often have to correct the cars tendency to pull left and (b) the steering wheel is down slightly to the left when driving straight on a perfectly level road. I've checked that each tire was installed in the correct locations, air pressure, etc. The fronts are looking a little worn but not too bad. What's strange is that everything was fine last year right up until I put the winters on.

BMW has no idea what the problem could be.

Any ideas?
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  #2  
Old 05-16-2006, 09:57 PM
SoCaLE39 SoCaLE39 is offline
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Sounds like you have radial pull which can even happen with new tires
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  #3  
Old 05-16-2006, 10:18 PM
325ic a beer's Avatar
325ic a beer 325ic a beer is offline
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Doh!

I hate it when that happens. And it HAS happened to me as well.
I bet there are others that have had the exact same thing happen at one time or another. Especially if you've lived in a colder climate and have actually had two sets of tires for your car. Snows and summers.
I'm feelin your grief.
On a problem solving note,,,,
Tirerack has some great prices on boatloads of sweet tires.
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  #4  
Old 05-17-2006, 12:10 PM
franka franka is offline
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Left and Right
By Larry Carley

Diagnosing and Fixing Steering Problems Requires Complete Check
A vehicle that pulls or leads is a vehicle that needs your help. A "pull" means the vehicle wants to steer itself toward the right or the left. The only way to keep it going straight is to counter the pull by steering to the opposite side. Whether the pull is mild or severe, it requires constant effort by the driver and can be very tiring on a long trip.

A "lead" on the other hand means the vehicle has tendency to drift towards one side of the road or the other while traveling straight. It doesn't fight the driver like a pull, but still requires some correction to keep the vehicle in the center of the lane.

Then there's "steering wander." A vehicle that wanders is unstable and drifts one way and then the other. The condition often gets worse the faster the vehicle goes. The steering may also feel loose and require constant correction to maintain a straight course.

All three types of conditions are undesirable and may even be dangerous under certain driving conditions. On wet or slick pavement, it may increase the risk of a skid or losing control when braking hard (even with ABS). All three conditions also require constant driver attention and increase the possibility of running off the road if the driver's attention wanders.

Causes & Cures
The underlying cause of a pull or lead may be the tires, steering, alignment, suspension, brakes, the vehicle itself or a combination of any of these. So let's look at some of the things that cause a steering pull so you can figure out how to diagnose and correct this kind of condition.


Check the Tires First
The first thing you should check are the tires to rule them out as a possible cause. Check inflation pressures, tread wear, tire sizes and brands. Uneven pressure between the front tires can cause a pull or lead toward the side with the low tire. It usually takes a significant difference in pressure (8 to 10 psi or more) to create a noticeable pull, but some vehicles are more sensitive than others.

If a tire is low, reinflate all tires to the recommended inflation pressure and test drive the vehicle to see if it still pulls or leads to one side. If the pull is gone, you've fixed the problem. But if it still pulls, you need to keep looking.

Compare the amount of wear on both front tires. A significant difference here may create enough of a difference between the tire diameters to cause a pull. Rotating a worn tire to the rear axle should reduce its effect on the steering.

If either front tire has heavy shoulder wear, it may be the result of camber misalignment caused by a bent strut, spindle, mislocated strut tower, bent control arm, worn or collapsed control arm bushing, weak or sagging spring, shifted engine cradle or other frame problem.

Also, check for mismatched tires. Make sure both front tires are the not only the same size, but also have the same tread pattern and construction. If the OD of one tire is greater than the other, the steering will lead towards the shorter tire. Differences in tread width, design, sidewall stiffness and belt construction between the front tires may also create enough difference in rolling resistance to set up a lead or pull towards the side with the greatest resistance.

"Radial pull" is another condition that is tire-related. Sometimes a variation in a tire's construction creates conicity in the tire that causes it to pull to one side. The pull will remain to the same side whether the vehicle is being driven forwards or backwards. If you suspect a tire is pulling, switch the front tires side-to-side and see if the direction of the pull changes. If it does, the tire is to blame.

The cure here is to replace the bad tire, or if the customer's budget can't afford a new one, move the bad tire to the spare position or rear axle where hopefully it will have less of an effect on the steering.

Radial pull can also be caused by misalignment of the plies inside a tire. This creates a sideways push that causes the vehicle to drift to one side. If switching the front tires left-to-right causes the direction of the drift to change, you've diagnosed the problem.

Steering System Woes
Steering problems that can cause a pull include things like an imbalance in the power steering unit and what's called "memory" steer.

If the spool valve inside the power steering gear leaks internally and allows hydraulic pressure to flow to either side when power assist isn't needed, the steering will be unbalanced and will favor one side. One way to diagnose this condition is to start the vehicle with the front wheels raised off the ground. If the wheels slowly steer themselves to one side, you've found the problem. The fix is to replace the spool valve assembly, steering gear or rack.


Any time you suspect a power-steering related problem, you should test drive the vehicle and check for equal effort in both directions.

Memory steer is another condition that can prevent a vehicle from going straight. Anything that creates binding or excessive friction in the steering linkage or steering pivots may interfere with normal steering return and keeping the wheels centered following a turn. This includes binding in the upper strut mounts, in the steering gear or linkage, or in the ball joints.

To rule out these possibilities, raise the front wheels and steer from side to side. If effort is unusually high, inspect the tie rod ends and sockets, the rack yoke adjustment or amount of play in the steering box and the idler arm bushing. Replace or adjust as needed.

If you suspect binding in an upper strut mount or a tight ball joint may be causing the problem, disconnect both tie rod ends from their steering arms and turn each wheel by hand to check for resistance.

Another kind of memory steer can occur on certain Ford vehicles if the rubber-bonded tie rod ends have been disconnected and reattached or replaced with the wheels off-center. Rubber-bonded tie rod ends don't swivel like conventional tie rod ends. If installed with the wheels turned to either side they won't be in the center, relaxed position.

Misalignment Causes
If a vehicle has too much cross-camber or cross-caster it will lead or pull to one side. How much is too much depends. As a general rule, camber settings on both front wheels should vary from each other by more than half a degree. The same goes for caster on most vehicles.

Too much cross-camber can make the steering pull or lead towards the side that has the most (positive) camber or away from the side that has the least (negative) camber. Too much cross-caster can make a vehicle pull or lead towards the side that has the least (negative) caster.

Adverse changes in camber and caster settings may be caused by 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 a camber problem.

Also check ride height on both sides. A difference here can make the vehicle lean toward one side, producing unwanted changes in camber in one or both front wheels. The cure here is to replace any worn or damaged parts that are found, or to realign the position of the strut towers, engine cradle or subframe if structural damage is involved before readjusting camber and caster to specifications.

Inspect the Suspension
Steering stability can also be affected by the rear wheels. Rear axle steer can make a vehicle pull or lead to one side just as misalignment in the front. The underlying cause may be out of spec rear toe, a bent rear axle, chassis misalignment, or a stack up of assembly tolerances in the chassis that prevents the rear axle from being square to the vehicle centerline.

If you suspect a rear axle steer problem, measure and compare the wheelbase on both sides. If there's a difference, something is out of place. If the position of the rear axle can't be corrected easily or economically, do a thrust angle alignment to restore on-center steering and directional stability.

If you're doing a four-wheel alignment check, the presence of a thrust angle would tell you rear toe is off. Measure individual rear toe for both rear wheels and correct as needed using rear control arm adjustments or hub shims.

Stop Brake Contribution
If the vehicle only seems to pull when applying the brakes or for a short period after the brakes have been applied, it's likely one of the front brake calipers is bad or is hanging up.

Raise the front wheels and spin each wheel by hand to check for brake drag. Causes here include corroded caliper slide mounts or bushings that prevent a floating caliper from centering itself over the rotor, a frozen or sticking caliper piston, a plugged brake hose or line, or even an overfilled fluid reservoir in the master cylinder that doesn't allow the caliper pistons to fully retract when brakes are released.

Compare the thickness of both brake pads if a caliper seems to be dragging. If they're not the same, it's another indication that the caliper is hanging up and needs to be repaired or replaced.

Sometimes a dragging rear brake will cause a pull. Causes here might include weak drum brake return springs, misadjusted drum brakes, or misadjusted parking brake or parking brake pedal switch (creates residual pressure in the master cylinder to cause drag). If a rear wheel is dragging, pull the drum and inspect the brakes. Readjust or repair as required.

If a pull only occurs when the brakes are applied, the pull is due to uneven braking. 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 or frozen caliper or caliper piston, or by grease, oil or brake fluid contamination of the brake linings.

Another overlooked cause of a brake-related steering pull can be mismatched friction materials side-to-side. If the brand or type of brake pads installed on one front wheel are different from those on the opposite side, the difference in friction characteristics can make one brake grab harder than the other creating a pull. Ask your customer if the brakes have been worked on recently. If they have, it's possible somebody replaced the pads on one side only or installed a loaded caliper with pads different from those already on the vehicle.

Sometimes a worn or loose control arm bushing or strut rod bushing will allow alignment changes when braking, so be sure to inspect these components too before blaming the brakes.

Other Factors to Look For
Sometimes a steering pull defies diagnosis. All four wheels are within alignment specifications, the steering, suspension and brakes are all okay but the vehicle still leads or pulls to one side.

One clue here may be how the vehicle is loaded when it is being driven. If the customer hauls a lot of heavy cargo, he may be loading the chassis unevenly with more weight to one side. The resulting changes in alignment that occur as the springs are compressed may change camber and/or caster enough to cause a pull or lead. Evening out the load should help rectify this kind of problem.

But if the customer hauls a lot of stuff on a regular basis, some type of suspension upgrades might be recommended. A set of variable rate springs, stiffer springs, air springs or air shocks might help in handling overweight payloads.

Road crown can also cause the steering to lead toward the right. The center of many highways is slightly raised so rain water runs off to the outside for proper drainage. You can't do anything about changing the slope of the road, but you can compensate for road crown by subtracting a little caster from the left front wheel.

Could Be Bump Steer
Another kind of problem you may encounter is "bump steer." A vehicle suffering from this condition will steer and handle normally on a straight, flat road, but may suddenly jerk or pull to one side when it goes over a bump or dip in the road. When the suspension changes height, unequal changes in toe occur at the front wheels causing the steering to jerk one way or the other. The problem can be a bent steering arm, a steering rack or steering linkage that isn't parallel to the ground, or frame damage.

Another possible cause of bump steer is not centering the steering linkage before adjusting toe. This can also create unequal toe changes when the suspension moves up and down.

If the vehicle has a steering rack, inspect the rack mounts for damage or looseness. Measure the distance from both ends of the rack to the ground. If both distances are not the same, the rack is not square in the chassis due to mislocated rack mounts or possible structural damage.

If the vehicle has parallelogram steering, check the idler arm height, and adjust as required. The idler arm and pitman arm should be the same distance from the ground.

Measure the height of the outer tie rod ends from the ground. If different, one of the steering arms may be bent.

Torque Steer Causes
In some front-wheel drive cars, the steering pulls to the right under hard acceleration. This is called "torque steer." It occurs most often in FWD cars with unequal length halfshafts and is caused by suspension compliance that allows unequal toe changes when accelerating.

Torque steer is just a handling characteristic of some FWD cars, but things like loose or collapsed control arm bushings, loose or worn tie rod ends, or loose/broken engine/transaxle mounts can make it worse.

If torque steer is objectionable, inspect the suspension and replace any parts that are worn or damaged. You might also recommend installing aftermarket bushings that are stiffer and allow less suspension compliance under load.
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  #5  
Old 05-17-2006, 12:17 PM
franka franka is offline
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Swap the tires around and see what happens. If they are non-directional I would try swaping the 2 fronts 1st.

Maybe you mounted them differently than they were previously installed, particularily in regard to rotation.
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  #6  
Old 12-22-2006, 01:46 PM
zykac zykac is offline
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Quote:
Originally Posted by pmcwhinnie View Post
Hi,

I have a 2002 540i/M. Put my summers (SP Sport 2000 Es) back on a few weeks ago and have noticed that (a) I now often have to correct the cars tendency to pull left and (b) the steering wheel is down slightly to the left when driving straight on a perfectly level road. I've checked that each tire was installed in the correct locations, air pressure, etc. The fronts are looking a little worn but not too bad. What's strange is that everything was fine last year right up until I put the winters on.

BMW has no idea what the problem could be.

Any ideas?
alignment is your answer!
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