Mechanics

LINCOLN CONTINENTAL TIRE PROBLEM

2002 Lincoln Continental • 110,000 miles

I BOUGHT A 2002 LINCOLN CONTINENTAL WITH 100000 MILES AND THE STEERING PULLS TO THE RIGHT. I HAD IT ALIGNED AND IT DID NOT HELP. I CHECKED THE BRAKES AND THERE WAS NO DRAGGING ON EITHER SIDE. I PUT ON 4 NEW TIRES AND HAD IT ALIGNED AGAIN AND IT STILLED PULLS TO THE RIGHT. SOMETIMES IT SEEMS TO WONDERS. I BROUGHT IT BACK AND THE ALIGNMENT SHOP TWEAKED THE ALIGNMENT. THIS DID NOT HELP AND AGAIN IT WILL WONDER OR PULL TO THE RIGHT MORE SEVERE SOMETIMES MORE THAN OTHER. I HAD THE 2 OUTSIDE BALL JOINTS REPLACED AND STILL DID NOT HELP. COULD THERE BE ANYTHING ELSE I COULD TRY? COULD IT BE THE RACK AND PINION STEERING CAUSING THE PROBLEM? I DO NOT KNOW WHAT ELSE TO DO. DO YOU HAVE ANY SUGGESTIONS?
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Rickballinger
January 30, 2013.




Did they give you a printout of the alignment? What are the two camber and caster readings?


Caradiodoc
Jan 30, 2013.
NO I DID NOT GET A PRINT OUT, BUT THE ALIGNMENT SHOP IS VERY REPTABLE AND BEEN IN BUSINESS FOR A VERY LONG TIME AND THE MANAGER IS A OLD FREIND OF MINE. HE DID TELL ME THE ALIGNMENT ADJUSTMENT WAS TO THE END OF ITS LIMITS. HE NEEDED TO DRILL OUT THE WELDS ON THE STRUTS AND HAD TO ADJUST BEYOND THE LIMITS AND REWELD THE STRUT.


Tiny
Rickballinger
Jan 31, 2013.
Without numbers to look at it's hard to tell where to start. If "camber" is adjusted by moving the upper strut mounts, that is a very poor design to start with. Camber is the inward or outward tilt of the wheel as viewed from in front of or behind the car, and tires want to roll in the direction they're leaning. We make the left camber a little higher than the right side to overcome the car's tendency to go to the right due to road crown. That's the slant of the roads to the right so rain will run off.

Ford has always had very poor suspension designs and they often made their cars non-adjustable which resulted in terrible tire wear. The problem with making the upper strut mounts adjustable is that along with a tiny amount of camber change, that also changes "steering axis inclination". SAI refers to the pivots the spindle turns on when you turn the steering. There is no specification given for SAI. All that is critical is the two sides must be within 0.2 degrees of each other. More difference than that will result in less than ideal handling. All alignment computers measure SAI automatically, and a typical value might be around 28 to 32 degrees. To visualize that, from in front of the car, look back at the lower ball joint, then look at the upper strut mount under the hood. You'll see that upper mount is a lot closer to the center of the car than the ball joint is. Draw an imaginary line through those two points and that angle compared to true vertical is SAI. Now you can see that moving the upper mount changes SAI.

GM mechanics have been real familiar with the miserable handling problems on their front-wheel-drive cars for a long time. The front cross member has to be removed to work on the engine or transmission, and if it is not marked and reinstalled in exactly the same place, camber and SAI will be seriously wrong. An unneeded alignment can correct camber but SAI will still be wrong and will make the car real miserable to control.

Chrysler uses an adjustable upper strut mount on some of their cars too, but they have separate upper control arms with the upper ball joints that are the steering pivots. Those are real easy to adjust but they don't affect SAI.

I included a copy of my "Notes page" I made for my students that shows SAI better. This is related to that cross member on GM cars but the idea is the same.

Another thing you have to look at is ride height. Your buddy will have a small book that shows all cars, where to take the measurements, and what they should be. When the springs sag with age, the suspension geometry changes and that affects the arcs the control arms go through. Mostly that has an adverse affect on tire wear, (something else Ford owners are well aware of), but if the car is leaning more to one side, there may not be enough camber adjustment to bring it up to specs. It's important to understand that the alignment specs given are to achieve best tire wear, handling, braking, and comfort for a car in motion going up and down over bumpy roads. The suspension geometry is one of the factors designed in with those numbers in mind. When the car sits too high or too low, that geometry changes and there will be excessive tire wear even though the numbers look good on the computer. Those numbers reflect the car while it's standing still.

Another thing to look at is the gaps between the hood and both fenders. If they're both pretty tight, suspect the sheet metal is collapsing from fatigue. That is less of a problem on cars that have the upper suspension mounts close to the firewall which gives it more strength. When the upper strut mount or coil spring mount is half way between the firewall and the head light, it's easier for the sheet metal to bend. Some cars will have extra braces bolted between the center of the firewall and the centers of the fenders to fight that tendency for them to fold in.

Also, don't overlook a tire pull just because they're new. I bought a new set of tires many years ago and had such a bad pull to the right that I needed both hands to keep the car going straight. I just switched the two right side tires, then got 44,000 miles out of the set with no other symptoms. Switch your two front tires to see if the car goes straight or pulls the other way. If it does either of those, you'll know it's tire-related. If it still pulls the same way, it still COULD be tire-related but chances are it is not. Switch the two tires on one side and drive the car. If there's no change, switch the two on the other side front-to-rear and try it.

I still would like to know what the numbers are for your car. I made a printout for every one of my customers and put it on the front seat. If your buddy's printer isn't working, ask if you can write the numbers down if you have the car aligned again. In particular, the first things I look at is camber, caster, and toe for the two front wheels. The rear numbers aren't that important except for "thrust angle". That is the direction the rear wheels are steering. It should be 0.00 degrees meaning straight ahead. You can expect it to be off a little but too much can cause a pull in some cases.

Also write down SAI for both front wheels. That is considered a secondary alignment angle and we rarely look at it unless we're looking for the cause of a hard-to-diagnose problem or to verify the car was straightened properly after a crash.

All alignment computers can be set to display camber and caster to one or to two decimal places. Mechanics who set theirs up to only display to one decimal place, as in 1.5 degrees, are going for "good enough", close enough", or just plain speed. Mine was always set to display 1.53 degrees. That extra hundredth is very important on some cars. A typical camber reading on all cars other than Fords is roughly 0.50 degrees. The left side usually has to be 0.10 or 0.20 degrees higher to make the car go straight. If the actual readings are 0.45 on the left and 0.44 on the right, that is not nearly enough difference to offset road crown, but if the computer is set to round those numbers off, it would show 0.5 and 0.4 degrees which WOULD offset road crown and the car would go straight. If your mechanic has his computer set to read to the hundredths of a degree, it shows he wants to be more precise, and he knows it is going to take him longer to do each alignment, and he is willing to provide that higher level of service. Adjusting cars to just the tenth of a degree is good enough to get acceptable tire wear, but I've run into a real lot of cars that MUST have exactly 0.06 degrees difference to make them go straight. The computer has to be set up for more accuracy to achieve that.

Ford has always designed their cars for comfort at the cost of giving up tire wear. You test-drive a car and make purchasing decisions based on handling and comfort, not tire wear that will take a long time to show up. They tricked a lot of people with their Escorts and Tempos years ago. A typical camber spec is around 0.00 to 0.50 degrees. (For reference, 90 degrees would mean the wheel was laying on its side). A few cars called for real extreme settings of as much as 0.75 degrees. That was a lot but it was what was found to give the best tire wear on those models. The Escort and Tempo called for 2 11/16 degrees! You could see those wheels tipped way out on top as you passed them on the highway. There was no adjustment provided either. What you had was what you got. Because those cars rode on just the outer edges of the tires, they rode very smoothly compared to any other brand of car so they sold a ton of them. What the salespeople didn't want you to know is there was no way you could get more than 15,000 on a pair of tires. The rear wheels tipped way in on top but the aftermarket industry came up with ways to correct them. These cars also had a real huge problem with ball joints and tie rod ends separating leading to loss of control and crashes. Most auto parts stores couldn't restock them fast enough to meet the demand. At the chain store I worked at in the '80s we got in 40 Escort tie rod ends every Wednesday, and by Saturday they were used up and we were ordering them locally from the auto parts stores.

Many of Ford's rear-wheel-drive cars in the '90s called for half a degree negative camber which also goes against the alignment specialists' training and experience. I don't know if they did that for improved handling or if that's what they found gave the best tire wear. If your car calls for negative camber, your friend might be trying to raise it up closer to 0.00 degrees where logic says it should be, and that might be why he is running out of adjustment. If that is not the case, running out of adjustment has to be due to metal fatigue, ride height, or a bent part.


Caradiodoc
Feb 1, 2013.
I HAD THE ALIGNMENT CHECKED AND HERE ARE THE NUMBERS

LEFT FRONT - CAMBER -0.9 CASTER 4.4 TOE 0.02
CROSS CAMBER 0.0 CROSS CASTER -0.1 TOTAL TOE 0.02
RIGHT FRONT - CAMBER -0.9 CASTER 4.5 TOE 0.00

LEFT REAR - CAMBER -1.2 TOE 0.08
TOTAL TOE 0.16 THRUST ANGLE 0.00
RIGHT REAR - CAMBER -1.6 TOE 0.09

HERE IS THE COMMENTS OF THE TECH: FOUND NO WORN SUSPENSOIN PARTS. THE ALIGNMENT SHOULDN'T BE CAUSING A PULL. THE PASSENGER REAR CAMBER IS OUT OF SPEC AND WOULD NEED AFTER MARKET ADJUSTERS INSTALLED.
TESTED THE TIRES ON THE 9700 TIRE BALANCER AND IT SAYS THE TIRES ARE CAUSING A 22 POUND PULL TO THE RIGHT. THIS WILL BE CAUSING THE PULL. TIRE SIZE IS 225/60R16 H-RATED THE TIRES ON THE VEHICLE NOW ARE S-RATED.


Tiny
Rickballinger
Feb 4, 2013.
Dandy. Ford has always had issues with poor suspension designs, but this car is a mess. It looks like the mechanic did the best he could with what he had to work with, but here's my observations: LEFT FRONT - CAMBER -0.9 CASTER 4.4 TOE 0.02
CROSS CAMBER 0.0 CROSS CASTER -0.1 TOTAL TOE 0.02
RIGHT FRONT - CAMBER -0.9 CASTER 4.5 TOE 0.00

-0.9 degrees camber means they are tipped in on top a real lot. No alignment specialist, except possibly at a Ford dealership, could live with that. The right wheel is perfect for racing on an oval race track and making just left-hand turns. Both tires are running on the inner edges and that's where you will find the most wear taking place. The only thing good about front camber is both wheels are the same so their pulls will counteract each other. Remember though my comment about reading to the hundredth of a degree. You could have -0.94 on the left and -0.86 on the right. Both would be rounded off to -0.9 and appear equal, but in reality you have 0.08 degree pull to the right which is significant. With no more accuracy to look at, I'd like to see the left camber raised to -0.7 or -0.8 degrees. OR, ... The right could be lowered even more but I'd hate to make bad tire wear even worse.

Caster has no direct effect on tire wear and very little indirect effect. It also has almost no effect on pull on most front-wheel-drive cars. It does affect pull on rear-wheel-drive cars about half as much as camber does. Caster is easiest to visualize of you look at the fork of a bicycle or motorcycle. It goes forward as it goes down. That is positive caster which all cars use since the 1960s. It makes a more stable car to steer but it makes it harder to turn the steering wheel, so they added power steering to overcome it. Positive caster makes each wheel want to turn toward the center of the car. They balance out when you connect the steering linkage between them when they're equal, but on your car the right caster is 0.1 degree higher than on the left side so it is pulling to the left a little harder than the left wheel is pulling to the right. Again, with the less-accurate readings only to the tenth of a degree, it's impossible to know for sure, but 0.1 degree caster difference is not enough to overcome road crown. Without more accuracy, the two front wheels are too equal. If there is no other underlying cause, you will find the car pulls left when you're in the left lane of a two-lane highway.

The two toe readings are not equal which at first glance would say the steering wheel is off-center, but the difference is REAL small. Too small to be noticed, and it can easily be due to normal play in the steering system. Alignment computers can be set to read toe in inches or in degrees. At the moment I can't remember which is which but one method turns out to be exactly double the other. As I recall, I believe 0.06 inches equals 0.12 degrees. I'm accustomed to using inches, and 0.06" is 1/16". That's a typical setting for a front-wheel-drive car. It means the fronts of the tires are 1/16" closer together than the rears of those tires. The goal is that road forces pull the tires back and make them perfectly parallel for best tire wear. Rear-wheel-drive cars which don't have the engines tugging the tires forward usually call for 1/8" toe-in to make up for road and braking forces.

With only 0.02 inches or less toe-in, your wheels are starting out almost parallel already, then when you add in road forces, they are going to pull outward in the front and both will be steering away from the center of the car. Since the car can't follow two tires going in two different directions, it has to pick one, and that one will be the tire with the most weight on it. Usually that's the right tire. Since roads lean to the right, so does the car, and that puts more weight on the right tire.

Besides the pulling problem, not enough toe-in will cause accelerated wear to the inside edges of both tires. Imagine holding a pencil straight up with the eraser down. Set it on a table, push down on it, then slide it sideways across the table. The leading edge of the eraser will make eraser crumbs and wear down, but the trailing edge will bend up and no wear will take place on that part. The same thing happens on your tires. First you have to understand what is meant by the "leading edge" of the tire. Your tires are too far apart at the front. When you add in road and braking forces, both tires turn out more. The right tire is turned a fuzz too much to the right. Imagine it is turned more to the right, ... And more, ... And more, until it is turned 90 degrees. That's twice as far as you can actually do with the steering wheel. NOW you can see that the inside sidewall and edge of the tread is in front and is the first edge of the tread to come down the road. The inner edge is the "leading" edge. Okay, it's not nearly that severe, but as with the pencil eraser, those leading edges on both tires are what is going to scrub off on the road while the trailing edges will tend to lift up and not wear so much.

Excessive camber only affects the wear on that one tire, (although in your case camber is off on both tires). Incorrect total toe always affects both tires equally In your case, Ford gave you excessive negative camber on both front wheels and the mechanic gave you insufficient total toe-in. Both of those will cause accelerated wear on the inner edges of both front tires. I should qualify that by saying I left my job as an alignment specialist to go into teaching in 1999. At that time there were a few cars and full-size vans starting to show up that DID call for only 1/32" total toe-in, and they did achieve decent tire wear. Before you tell your mechanic I said he has total toe set wrong, find out what the specs call for. He might have it set right according to the book, but setting it to a little more toe-in might reduce the tendency to pull right.

LEFT REAR - CAMBER -1.2 TOE 0.08
TOTAL TOE 0.16 THRUST ANGLE 0.00
RIGHT REAR - CAMBER -1.6 TOE 0.09

My next point of concern is the rear camber. You should be able to stand behind the car and see the right wheel tipped in on top. 1.6 degrees is a pile. That's how the older Escorts and Tempos came, but we had kits available to help correct Ford's terrible design. Your mechanic made reference to an adjuster that can be installed to correct that. I'd get that done. At least it will reduce the wear on the inner edge of that tire. It may reduce the pull to the right too. Normally rear camber has such a small effect on pulling that we ignore it, but when you're looking for the elusive cause of a pull and you have something so severe staring you in the face, it IS possible it is related when it's this bad. Negative 1.6 degrees means the tire is tipped in a lot on top. That will make it want to pull to the left. It will normally just follow the car but when it's so high, it can make the back of the car go to the left which would turn the car to the right.

Related to that, here are some generalizations that can sometimes provide clues. When you let go of the steering wheel and it turns to the right by itself and the car goes to the right, it is usually caster-related. Caster numbers refer to when the wheels are pointed straight ahead. The amounts change, (but can't be measured), when you turn. One side goes up and the other side goes down. After you turn a corner and the two sides are different, they want to come back to where they're exactly equal. That's what makes the steering wheel return to center by itself. While driving down the road, if caster is not equal on both sides, the steering system will want to turn until they ARE equal and balanced out. You see that by the steering wheel turning a little when you let go of it.

When you have a pull related to unequal camber, the steering wheel will stay perfectly straight when you let go of it, but the car will go off to the side. This can be confusing because you have to turn the steering wheel the other way to counteract that pull. Tire pulls will also not cause the steering wheel to turn

If the rear tire is steering the car to one side, you will also not see the steering wheel turn when you let go of it. These are generalizations, and they all assume everything else is equal side-to-side and correct. When multiple things are wrong, it's hard to know how the car or the steering wheel will react.

Another thing you have to be aware of is how the manufacturer determines their preferred alignment settings. A common spec. That I'm very familiar with for front camber is 0.50 degrees plus or minus 0.50 degrees. That means anything between 0.00 and 1.00 is acceptable. In reality, either of those two extremes would result in accelerated tire wear over time and no alignment specialist would set them there. All those numbers mean is if the alignment is checked while that vehicle is under warranty, they are close enough and the manufacturer will pay for the alignment check, but not to have any adjustments made. This reduces the number of alignments they are obligated to pay for. When it comes to taking your money for an alignment, we normally want to give you the best service possible. To do that, every alignment computer has a "reduce tolerance" button that will shorten the range of acceptable numbers forcing us to set each wheel closer to "perfect". Instead of 0.50 degrees plus or minus 0.50 degrees, it will read 0.50 degrees plus or minus 0.15 degrees. We don't get so much leeway now. We have to be more precise. Your mechanic may have not pressed the "reduce tolerance" button because we become accustomed to what settings are in your best interest without needing the machine to tell us. That button becomes more valuable when we want to show you on the printout why we needed to do something for you. Once we reduce the tolerance and a number is out-of-specs, there will be a message to that affect on the printout. People believe printed messages more than they believe their mechanics.

The last thing has to do with the tire pull. Seems the cause of the pull has been identified. Switch those two tires side-to-side. There's a small chance the car will still pull the same way. If it does, switch them front-to-rear. I'm surprised the mechanic didn't switch them while he had them off the car.

1) Switch the right front tire.
2) Have the adjustment installed to raise right rear camber to less negative.
3) Ideally, raise left front camber from negative 0.9 to negative 0.7 degrees.** Less ideally, increase right front caster to make that wheel pull harder to the left, or lower left front caster to make that one pull less hard to the right.
4) Measure ride height and compare to specs. Sagged springs result in increased tire wear even when the car appears to be in perfect alignment. They don't cause a pull unless they are sagged unevenly.
5) Increase the amount of toe on each wheel by 0.02 inches unless it is at specs right now. That will bring total toe to 0.06 inches which closer to the 0.12 inches most cars use.

** Car models vary a lot in how much affect any alignment setting has on pulls and tire wear, and they vary a lot on how much unequal caster and camber settings can offset each other. I don't have a good feel for this car model in particular. One more thing you can look at is to see if they list the same caster and camber specs for both sides in front. If they do, which is most common, they are leaving it up to the mechanic how much left-hand pull to adjust in to offset road crown. Ford often gives two different specs for the left and right side indicating they know how much side-to-side difference is needed. In that case, it can be possible to set both wheels the same and have them be in specs but not be correct. When they specify a setting to create a left-hand pull, the car needs that.
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Caradiodoc
Feb 5, 2013.

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