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Thread: Steering improvement / the 2014/15 Mirage steering problem

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    Steering improvement / the 2014/15 Mirage steering problem

    After buying this car, I soon developed pain in my wrists and hands, especially after long distance driving. This was reason enough to do something about the stiff and crappy steering, unless I wanted to settle with arthritis for the rest of my life from this car's inferior steering.

    A lot of folks complain about the lack of self-centering of the steering. I would describe it as "sticky", in the sense that the steering wheel feels like there were some form of brakes attached to it, preventing the steering wheel from turning freely and easily.

    After analyzing the the problem thoroughly, here are my findings plus some methods of getting improvement that really help. May this contribute to understanding the problem, which was the reason for writing.
    Note: The bespoke methods of getting improvement is of course only at your own risk, and only for those who truly know what they are doing! Nothing at all for amateurs, sorry! Don't blame me if you mess anything up and wrap yourself around a tree.

    The problem:
    The problem is caused by much too high total torque (stiffness) in the total steering system. The torque required to turn each of the four balljoints, plus turning the electric steering column, plus turning the steering box (rack) sums up to the total torque (stiffness) within the steering. BTW, the upper support bearing is ideal, and thus not part of this problem.
    Think about it: If the torque required to turn the wheel is greater than the feedback forces from the road, no feedback will ever reach the steering wheel!
    There are actually three major problems. All three contribute to the crappy steering problem, and two of the three causes can be reduced. The result is a much better steering.

    Problem 1:
    The electric steering uses a torque sensor in the steering column, right after the steering wheel to tell it how much turning-force you are putting onto the steering wheel, and in what direction that force is pushing. First there is an initial force, then after it is applied strong enough, the wheel may turn. No force no turn.
    The power steering electronics senses that force, and applies motor assistance to the motor, which is actually geared to the steering-column below the torque sensor.
    Otherwise said, that means the column with the built-on gearbox of the assisting motor applies a frictional force (brakes) to the column. That force has to be overcome first, in order for the sensor to figure out the wheel has a turning-force put to it. Only after that force is overcome, will the assisting motor be driven in order to stop the turning force (the torque applied) from increasing further. If that force comes from you, you need to be applying an initial torque before the wheel will even begin to turn. If that force comes from the road, the friction in that steering column between your hand on the wheel and the force coming from the road will prevent you from receiving the "feel of the road". This is also because the power assisted steering actually powers the electric motor in the opposist direction, because it senses a torque coming from the road. The result is the lack of "feel of the road", and that includes all forces from the road, self-centering included. I have not found a way to reduce the torque of the electric worm gear.




    Problem 2:

    The rack. The steering shaft including bespoke power assist drives (turns) the pinion of the rack-and-pinion steering-box (the rack).
    In order to prevent lash in the steering, and also for the steering to have a dampening function, a stationary piece pushes on the back of the rack, which pushes the racks teeth towards the pinion gear. Any movement of the rack has to overcome the friction of the stationary piece pressing on the back of the rack. This prevents lash and introduces dampening by adding friction. There is a factory-adjusted nut plus a spring pushing the stationary piece onto the back of the rack. Usually these are adjusted to create a certain torque (friction) typical for unassisted steering systems. Our cars don't really need that much dampening. It can therefore be substantially reduced.

    Problem 3:
    Lookup the FSM and add up all the ridiculously high permitted torque levels within the total steering system! No wonder the steering is like it is.
    According to the FSM the Lower arm ball joint torque should be Nm (in-lb) 0.1 to 5.0 (1 to 44)
    I would call a lower arm ball joint with a turning torque of 5,0Nm a piece of junk and a factory reject! Such high permissable torque may have been acceptable in 1950.

    The FSM says the tie rod end ball joint turning torque should be Nm (in-lb) 5.0 (44) or less
    I would call a tie rod end ball joint with a turning torque of 5,0Nm a certain factory reject!

    Some improvement:
    Tie rod end ball joints can be obtained easily as after-market replacements for very little cost. If you examine the joints of your car and they are stiff, then think about replacement!
    You can expect the torque of a typical quality replacement to be not higher (stiffer) than about 1.8Nm. There is no reason to be satisfied with unnecessarily stiffer joints. To put it in plain words, ball joints manufactured under today's industrial standards will have less than half the stiffness that the FSM permits!

    Unfortunately I have not found any replacement kits for the lower arm ball joints yet. When they do become available as after market parts, I will certainly check their torque and consider replacing them too.


    Further improvement:
    The initial adjustment of the rack was done in the factory before the steering box was put into the car. In manufacturing, the rack is pulled and consequently the pinion gear turned, the resulting force metered. See FSM. The torque adjustment is made, and the counterlocking nut put on and stuck tight. This factory-adjusted force was way too high for my liking.
    The adjustment-nut was loosened a bit and turned back in by hand till it just started applying pressure. from that point on, it was tightened one third of a revolution. Special tools are absolutely necessary.
    If the adjustment is too tight, the steering sticks badly, and thats very dangerous! If it is too loose, the rack-and-pimion will rattle when driving over uneven roads. If much too loose, the car may turn without the steering moving accordingly. Thats very dangerous.

    Warning! The reason for this write-up is for understanding the problem. Only fiddle with it if you must, and at your own risk, and do not blame anyone except yourself if you goof it up! Modification is only for those who truly and really know and understand what they are doing! If you are not positive you can master it, leave it be! Don't blame me if you mess anything up and wrap yourself around a tree, and messing it up is terribly easy


    Last edited by foama; 10-01-2016 at 12:34 PM.

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  3. #2
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    Great write up, and for those who wish to follow with his prior exploration into the mirage's steering problems can do so here

    http://mirageforum.com/forum/showthr...t-for-steering

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    Senior Member Cani Lupine's Avatar
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    I wonder if it's possible to completely remove all of the electronic assist junk and leave behind a regular rack-and-pinion.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 49.2 mpg (US) ... 20.9 km/L ... 4.8 L/100 km ... 59.1 mpg (Imp)


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    Quote Originally Posted by Cani Lupine View Post
    I wonder if it's possible to completely remove all of the electronic assist junk and leave behind a regular rack-and-pinion.
    If the force required to turn the gears of the steering-assist could be lowered, the problem could be reduced.
    I don't want to take those plastic gears apart.

    Maybe someone already had the actual gears open and can tell us about it?

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    Administrator Daox's Avatar
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    ThreePot has done the most looking into this from a physical part perspective. He posted info here:

    http://mirageforum.com/forum/showthr...ll=1#post20923

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Senior Member Ares's Avatar
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    Just putting a wider wheel+tire setup has given me enough to work with.

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    just wondering if the 15 inch wheels have better self centering than the 14 inch

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage gs 1,200.0 automatic: 35.1 mpg (US) ... 14.9 km/L ... 6.7 L/100 km ... 42.1 mpg (Imp)


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    15 or 14 inch wont matter, it's the width of the rim and tire. Try 15x6.5 for a common size, 15x7 may work with proper offset but they will be harder to find, and this will hurt mpg

  10. #9
    Senior Member Ares's Avatar
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    Agreed. I'd say 185 up works. I loved my 205s but they were rubbing the fender

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    Member bzacon's Avatar
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    After putting on a set of 6*15 integra gsr rims with 195*50 R15 Toyo Ecstensa HP all seasons, I can confirm that wider/thinner tires on a larger rim within reason do not help, although the car feels better overall, steering is still garbage.


    2014 Mirage GLX 5MT Plasma Purple
    2004 Accord EX 5MT Graphite Pearl RIP

    No one ever went broke underestimating the intelligence of the American public. -- That's why Ford outsells Mitsu in the US

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