Steering problem

Tiny
JIMRAIO
  • MEMBER
  • 1998 LINCOLN TOWN CAR
  • 4.6L
  • V8
  • RWD
  • AUTOMATIC
  • 100,150 MILES
After turning left or right the steering wheel does not come back on it's own I have to pull it back to straight I checked the front end it's fine a repair shop said it could be the power steering pump or the steering box can you tell me which one it is without changing one to find it's the other one. P.S. There are no leaks fluids are full and no whining or noises. Please help. Thank you. Jim
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Friday, November 13th, 2015 AT 9:49 AM

4 Replies

Tiny
CARADIODOC
  • EXPERT
This is not a power assist issue. You can prove that by carefully shifting to neutral while driving, stopping the engine, and the "memory steer" problem will still be there. There's two common causes for this and it depends on how or when the problem started. If it was right after an alignment was performed, there is likely too little "caster". Caster can be explained a number of different ways, but the easiest way to think of it is to look at the fork on a bicycle or motorcycle. It is angled toward the rear at the top. That is what allows you to ride no-handed when there's weight on the front tire.

Caster on a car's front wheel is what causes the steering to return to centered when you let go after making a turn. Many years ago cars and trucks used negative caster, meaning the fork on the bicycle would be slanted backward, and that caused real easy steering with no power assist. In the '60s when people started driving at faster speeds, we went to positive caster, which everything uses today, to give the vehicles more directional stability without having to constantly adjust the steering wheel. That higher caster made the cars more stable, but it resulted in much higher turning effort too. We added power steering to overcome that increased effort.

Caster changes on each front wheel when you turn to one side, and like a teeter totter that wants to be balanced, the front tires want to return to equal caster on both sides, and that is when the steering system is centered. Too much caster will spin the steering wheel back to centered much too quickly. Too little caster will make the steering system lazy and not return very fast. The additional clue is the steering wheel will turn to the side and back to center with the same effort as it always had when the car is standing still.

If this problem occurred on its own, and gradually got worse, it is almost certain you have a tight ball joint. To verify this, raise the front tires off the ground, then see how hard it is to turn the steering wheel. If it's rather hard to turn, you need to disconnect the outer tie rod ends so each wheel can be turned independently by hand to see which one is causing the problem. The tight turning can be a little hard to discern while stopped because it's hard to turn anyway due to the tires' friction on the road surface. The steering isn't going to ever return on its own unless the car is moving, so that can't be used as a clue.

Tight steering isn't real common on Ford products. They have way more trouble with steering and suspension parts becoming sloppy and separating leading to loss of control and crashes. Those systems should be inspected at least once per year, and anytime a new noise or vibration occurs. Tight ball joints are filled with rust, so while they will appear to be okay under a visual inspection, they can actually be getting ready to fall apart.
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Friday, November 13th, 2015 AT 7:28 PM
Tiny
PATRICK PERUSSE
  • MEMBER
I have the same problem with my 2002 Lincoln Town Car. The problem has always been there and has gradually gotten worse. I replaced the sway bar links, upper and lower ball joints, and outer tie rod ends (inner tie rod ends we re fine).. After all that front end work, I went ahead and had a front end alignment done. The alignment was within spec with the exception of the caster on both left and right side were 5.0 and 4.5 deg, respectively (spec range is 5.3-6.8 deg). I assume that the alignment guy couldn t get the caster within spec for some mechanical reason.

The car is fine to drive but I would like to improve the return to center of the steering as it makes the car slightly more difficult to drive with the current characteristic as mentioned in your response.

What would you recommend to get the caster within spec and or improve the steering?
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Thursday, October 11th, 2018 AT 4:30 AM
Tiny
KEN
  • ADMIN
Hello,

It sounds like the power steering box is going out which gets harder to steer and not returning here is a video showing the job being done on another car but the process is the same with diagrams below to show you what to do to fix the problem on your car.

https://youtu.be/KKeFqHLuRQ0

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Saturday, October 13th, 2018 AT 1:52 PM
Tiny
CARADIODOC
  • EXPERT
Another thing to consider is sagged front coil springs. Most alignment specialists will measure ride height before attempting to align a car, and they will want to correct that first. Being too low in front reduces caster, and it will reduce the highest it can be adjusted to. 3.0 degrees caster is typical for most cars and is a very common spec. This car model is known to not have very good "returnability", and the need to go higher than 6.0 degrees bares that out. That really high setting is trying to overcome the design of the steering system. Also, to address rapid tire wear due to the design of the suspension geometry, a lot of Ford car models call for negative "camber", meaning the wheels are tipped in slightly on top instead of tipped out, which is almost universal among other car brands. Cars with negative camber seem to have a more mushy or softer road feel, and steering effort, which contributes to the softer steering return. That is a desirable characteristic of luxury cars, but that applies more to when they're fairly new. With age, weak springs, metal fatigue, slightly-worn rubber bushings, and wear in the steering gear box all contribute to changes in the steering system's personality.

Sagged springs change the geometric shape or relationship of the suspension system's parts, and that causes the wheels to tip in and out on top going through the wrong motions as the car body bounces up and down over bumps on the road. That can lead to accelerated tire wear and increased steering wander even though the numbers on the alignment computer look perfect. Higher caster reduces the car's tendency to wander but it requires higher effort at the steering wheel. To address that, larger Ford car models use steering gear boxes that require more steering wheel revolutions to turn a corner compared to those on smaller front-wheel-drive cars. That makes it easier for the steering wheel to turn the wheels, but harder for the wheels to return the steering wheel. The gear ratio of the steering gear box is a big contributor to slow steering wheel return.
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Saturday, October 13th, 2018 AT 8:34 PM

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