Steering improvement / the 2014/15 Mirage steering problem

[Marklovski]

Putting lighter rims and coilovers on has helped the steering to become lighter.

[MightyMirageMpg]

Have you checked that you don't have excessive caster or kingpin inclination angle? Idk if it's even adjustable but if somethings outta wack..

that will cause a harder than usual steering effort.

My car steers very smooth and easily, even within reason with the key off (depower)


Edit: 500th post!


2nd edit. Lol. Have you put an amp probe on the motor and gearbox? I'm curios maybe you've got an issue. There's no way my car would come close to damaging wrists. Not even old lady wrists


3Rd edit... I see this was from 2015.. My 500th post was made in vein.

[foama]

There seems to be wide consensus the steering is garbage, and looking through the FSM, the problem and their causes become obvious. The steering force at the steering wheel according to the FSM is 20N.m / 4.5lb or less. At almost five pounds needed to make the wheel move, it is logical that on a straight stretch of road the car actually moves zizag.

Why? On a straight road the car travels forward eventually getting closer and closer to one side, and you begin to try correcting the steering wheel to keep it in your lane. At a force of full 4.5 pounds, the steering wheel suddenly overcomes its "sticking" and jerks towards the chosen direction, jolting a bit further in that direction than you actually wanted. After a few seconds or so the car is getting too close to that side, you need to correct the wheel again, and the same happens all over again and again. The result is a zigzig travelling car, a correction happening every few hundred yards or so, rather than a straight line of travel.

Just to repeat and make it clear, you need full 4.5 pounds of force applied to the steering wheel to make it budge, and Mitsubishi calls it normal! (See FSM, page 37 - 60)
If you want to break down those forces further, the FSM states as normal:
Steering Gear Pinion Torque of 0.6 - 1.3 N.m being 5.0 - 12.0 in-lb. or less
Total rotational Torque of Steering Column Shaft (with servo mechanics built on) 1.25N.m being 11 in-lb or less.
All these forces are to be measured on the actual assemblies. In lack of taking it all apart, you could just measure the steering force at the steering wheel with both wheels lifted off the ground.

With the FSM permitting such high torques, it is no wonder at all why the steering feels like garbage, so crappy, sticking and numb. On my other car, a 20 year old Italian make without any power steering, about one-third of one pound is needed to make the steering wheel move. Wow! What a big difference, only one-fifteenth of the force needed on a twenty year old car! Its steering is perfect, with a fine feel of the road, and almost no force needed on the highway, and it doesn't even have power steering! What a far cry from the Mirage.


I decided get to the bottom of this, to see if it can be remedied.
The following explains the findings for understanding the problem, and if your conclusion is to correct something, it is at your own risk.
The steering column including attached worm gear and servo motor are too difficult to modify. Although the permitted torque seemed too high, I didn't want to mess with that. The comparable high torque is due to this particular construction principle and is part of the assembly and was made that way.
That left all the other parts. This meant the steering gear and all the ball joints were left for examination.
The tie rod end ball joints were OK and completely normal. The road wheels on the jacked-up car could be turned easily with removed tie rods, therefore the bottom ball joints were also OK. This only left the steering gear to be inspected.

The removed steering gear looks like this:




There is a crown nut which pushes a die-cast piece onto the smooth back of the steering rack, in turn pushing the toothed side onto the pinion and creating a frictional force between the sliding (traveling) rack within the assembly. The friction applied to the rack is by the die-cast block rubbing on the smooth back of the rack. It is virtually the same as a steering damper, much like a shock absorber in suspension. Remember, vintage cars had adjustable friction shock absorbers. The same physics apply.

The crown nut, secured by a 4 cornered nut:




The crown nut taken off reveals the view to the die-cast piece within the recess, the spring in the middle, and the flat bottom of the crown nut which pushes onto the spring. That looks like this:



The following picture shows the mounted crown nut on the right, and the back of the rack in the foreground. It is the back of the rack that the die-cast piece gets pressed on, by the pressure applied by the adjustable crown nut:



This shows the other (toothed) side of the rack:




What I then did corrected at least 80% or so of the problem. If you want to do similar, it would be totally at your own risk.
The crown nut was marked with a felt pen, see pix. The nut securing the crown nut was loosened a turn or two, and the actual crown nut was loosened about three turns. The Crown nut was then slowly retightened by hand. I could feel when the spring (see pix) started touching the nut and was starting to get compressed. From there on, the crown nut could be turned almost two full turns before the spring became all the way compressed and it couldn't be turned any more without force. The crown was loosened by one 1/12th of a turn (five minutes).

The measured Steering Gear Total Pinion Torque was now about 1.3 N.m being about 12 in-lb. This corresponds to the maximum allowed torque according to the FSM. This is way more than my liking!

From the "all the way in by hand without force" position, the crown was loosened by one full turn. This now corresponded to about 0.6 N-m or 5 in-lb, This is the minimum according to the FSM, and the steering was much better in that setting!

Further loosening makes the steering move even more effortlessly, but it should not be loosened too far! If it is too loose, the steering will start to rattle when driving over uneven roads. This is the rack moving around sideways within the assembly, and you certainly don't want that. Carefully readjusting that nut and rechecking multiple times brought the correct adjustment.
The crown nut was secured by means of the 4-sided counter nut.

NB:
All the pictures above show the cleaned ungreased and removed steering gear.
It is not needed to remove it out of the car as I did for examination.

NB:
The steering gear must be lubed (greased) lightly on both sides of the rack and on both ends. Both tie-rod ball joints inside the bellows must be well greased if they are to last.
The FSM recommends AUTOLEX A, which is a normal NLGI 2 multipurpose lithium grease.

Just to mention it, this car has 165mm wide tyres, and the alignment is perfect.


Following picture showes the crown nut as on the steering gear in running condition. The black thing across the very bottom is the front axle assy. The stabilizer bar is partly hiding the crown nut. With the bolts for the two rubber blocks of the stabilizer bar (see top left) taken off, the bar can be lifted for better access to the crown nut and the nut securing it. For acessing, the car must be level and firmly secured on blocks, with the front wheels off the ground.






FYI:
Why do some cars have steering dampeners or high friction within the steering?

Number one, cheaper power assisted steering uses worm gears, and they as inherantly "low backlash" designs, cause unwanted higher torque within the steering column assembly. The torque sensor in such systems is usually mounted directly after the steering wheel, rather than within the steering gear. This counteracts the "feal of the road" forces because the power assist system directly neutralizes them.

Number two, cars with high body roll can experience self-oscillating steering in certain rare conditions, which can scare the daylights out of inexperienced drivers and thus cause accidents. High friction (dampening) prevents any such oscillation.
Steering oscillation can occur when the steering is turned about a quarter turn or more under heavy accelleration, when the driver then suddenly take his hands off the wheel. The car and steering wheel will then rock swiftly and strongly sideways, from one side to the other, with the steering turning back and forth in the opposite direction of the body rolling, and all happening perpetually and increasingly strong. The way to get out of that situation is to firmly grasp the wheel and hold it for a second or so and then carefully correct the direction. Steering sytems with a built-in steering dampener or with high internal friction acting as a steering dampener will not oscillate like that.

[Daox]

Very interesting! Thanks Foama.

I am going to guess that with less friction, the power steering is engaging less and that you're getting a better feel from that. IMO the power steering is WAY overpowered on these cars and numbs the feel as you've mentioned. I would definitely like to try this out on mine. My electronic manipulation of the power steering system has yielded no results sadly.

[foama]

Very interesting! Thanks Foama.

I am going to guess that with less friction, the power steering is engaging less and that you're getting a better feel from that. IMO the power steering is WAY overpowered on these cars and numbs the feel as you've mentioned. I would definitely like to try this out on mine. My electronic manipulation of the power steering system has yielded no results sadly.

I forgot mentioning the adjustments can be done from underneath, the car being jacked up sitting on blocks. Please read and understand the entire post before doing anything.

Btw, I had the oscillating steering on my Suzuki Swift /Metro years ago (2005?), when the dampening nut (crown nut) was too loose. There should have been something about that in the Team Swift forum...

[Timinator]

I hate how easy the '18 steering is, if I could make my wheel 10-15% heavier I think it would be way better

[Mark]

I hate how easy the '18 steering is, if I could make my wheel 10-15% heavier I think it would be way better

I agree! The electric power steering is way over done. I tend to compare my Mirage to my old Ford Festiva, which was smaller & lighter than the Mirage. The Festiva had tiny 145SR12 factory tires, but it still tracked pretty good. All small cars get blown around some on windy days. Those 1988-93 Festiva cars were designed by Mazda, built by KIA, and sold by Ford. Power steering wasn't even an option, & I think they handled better on the highway without it. It may have been more of a pain to park, but I don't remember that even being an issue.

Power steering is only needed for slowing moving maneuvers like parking. I think the Mirage would handle better if the electric power steering was disabled past a certain speed like 10 mph, because you really don't need power steering on a small car like this once it's moving. It surely should be reduced at least! It would give the car a better feel at high speeds for sure.

The Mirage is also know for its tight turning radius. I somewhat wonder if that may contribute to this problem, too. One complete turn of the steering wheel is going to create a sharper turn than most other cars. Thus, the slightest movement of the steering wheel may cause more movement than your typical car. Just a thought?

[Timinator]

Wonder what would happen if we go into the ETACS and see if there is a power steering option??? Worst case **** it pop the plug off the rack haha

[Mark]

Wonder what would happen if we go into the ETACS and see if there is a power steering option??? Worst case **** it pop the plug off the rack haha

I don't think unplugging the electric power steering system would give you the same feel as a rack & pinion system designed without power steering, because you may be fighting the dead electric motor still attached to the system. I am not certain of that, but that would be my guess. When older cars had their power steering (hydraulic) fail, they did not steer as well as cars designed without it. You felt like you were fighting a dead system, which you were.

A small car like the Mirage really doesn't need power steering at all. It could be easily designed without it, and drivers would rave about how it handles on the highway. Consumers, however, believe power steering is a must have item. If this car didn't have it, car critics would jump all over that.

Electric power steering is nice for parallel parking, tooling around parking lots, and such. For 95%+ driving, it really isn't needed. If people drove both (cars with or without it) with an open mind on the highway, I am sure most would pick the car without it. It would feel extremely better, because you would truly feel the road. You are in total control verses a computer trying to guess what extra control you may want.

BMW (& others maybe) have systems where you can pick what type of electric steering control you want. I doubt that the Mirage's system is very sophisticated, & thus the gripe. Hydraulic systems kept improving over time. By the time we started replacing them, they were pretty good! Electric systems offer some nice advantages, but they are still being perfected. In the meantime, we complain about them. Especially those of us, that remember something else.

This is a nice short clip describing how power steering works (past, present, & future).

https://www.youtube.com/watch?v=o2kyozK9GII

[Timinator]

I know PS vs non-PS car are different, cars with out it have a higher gear ratio to make it easier. On hydraulic cars, I bypass the hoses and throw the pump away. I dont like a heavy wheel. I dont think the E motor would put a huge resistance on the wheel, assuming its a brushless motor you might feel it, but if its brushed, youll never even know its there. Something im going to check out someday for sure.