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BigJimnyMeet (North) 2024 (12 Jan 2024)


BigJimnyMeet 2024

14th July 2024
Parkwood Nr. Leeds

Booking now closed at 148 vehicles!!!



Looking forward to seeing everyone there

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Steering wheel slightly off centre

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18 Jun 2024 17:28 #256326 by lightning
The steering wheel on our 2020 Jimny has always been slightly off centre when driving on a straight road.
l never adjusted it and now it's done 20,000 miles. l had new tyres fitted today so decided to adjust it.

Easy l thought, just like the old Defender, adjust the steering arm a little to centralise the steering wheel.

And yes, only 1/4 turn of the steering arm and the wheel is perfectly aligned.

However, when driving in a straight line the steering wheel wants to return to where it was before, so the Jimny steers slightly to the right if you don't apply gentle pressure on the steering wheel to keep it in a straight line.

What's happening here, it is because the steering box has been in the same position for 20,000 miles and now is slightly different or is there something else.

l've adjusted it back to where it was before for now (l marked the position of the steering arm before adjusting it)

Never had this issue with my old Defenders. 

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18 Jun 2024 17:36 #256327 by DrRobin
The only thing I can think of is that the power steering is pushing it back to the original (neutral) position, but I wouldn’t know how you adjust this?

Robin

2020 blue SZ5 (one of the last to be registered in the UK)
Ex 2011 Blue Jimny SZ4
Northumberland Jimny Blog

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18 Jun 2024 20:32 - 18 Jun 2024 20:39 #256332 by facade
There was a thread on the steering pulling when a lift was fitted and the wheel straightened using the drag link, and the cure being to over-adjust the drag link slightly the other way, but I can't use the search on here very well.


The Gen 4 has stupid electric power steering instead of the perfectly reliable and infinitely superior (I think it is, but I don't care about having the steering wheel vibrate when the car thinks it is going over a white line) hydraulic system, and no-one seems 100% sure how it works.

There is a steering angle sensor that seems to be used to drive the self-centring action. The car "learns" the centre position somehow when the back wheels move- I suspect if they both move at the same speed it is going straight, and time to zero the sensor.

Why it makes a difference to self-centring I don't know, the steering angle is normally used in conjunction with the accelerometers to bang the brakes on on one side and try to drag the car round when it is skidding, there should be a torque sensor for the steering assistance.

On a proper hydraulic system the torque sensor is a twizzler bar in the steering column attached to the valves that controls how much power assistance you get, and the assistance operates to untwizzle the bar. The more you haul on the wheel, the more it twizzles up and the greater the amount of pressure applied to move the steering. When the wheels catch up with the steering wheel position the bar straightens out and the valves close.

Anyway, waffle aside, it is most likely something to do with the zero angle of the steering now being off. It should re-learn it if you manage to get in the secret condition that Suzuki specify, probably driving in a dead straight line at a specified speed.


Here is an article about the steering doing this when the car is lifted and adjusted using the drag link, I think the author is the person who posted on here.

teamghettoracing.com/vehicles/cars/2019-...#steering_after_lift


Certainly the EPS on mine feels very "odd" compared to the hydraulic on the Gen 3, and compared to the EPS in The Other Car. I feel twitches in the steering when driving straight at random times, I actually disabled the shakomatic lane departure thinking it was kicking in at random and it makes no difference.

If it suddenly breaks, go back to the last thing that you did before it broke and start looking there :)
Last edit: 18 Jun 2024 20:39 by facade.

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19 Jun 2024 07:23 - 19 Jun 2024 07:27 #256338 by lightning
Thank you for the replies.

Reading the linked thread, it seems that the steering angle sensors "learn" when the Jimny is doing straight ahead from the difference in rotation speeds of the rear wheels.

So l wonder if the system will "learn" the new position of the steering mechanism or has to be reset in some way before that happens?

l haven't changed the steering geometry only adjusted the position of the steering box slightly for the straight ahead.

There's no other way to do it, you can't take the wheel off and put it back on straight as apparently it doesn't like that either. Also it's not far enough off centre.
Last edit: 19 Jun 2024 07:27 by lightning.

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19 Jun 2024 09:02 - 19 Jun 2024 19:53 #256341 by facade
Adjusting the length of the drag link to move the steering box back to centre is the correct method.

You can measure the SAS output angle with SZviewer or similar from the OBD port, then if it isn't zero it can be reset with a suitable OBD tool.


I've given it some thought, and I wonder if there is something fundamentally wrong with the steering geometry on the Gen 4 and the ECU acts to power centre the wheel to the SAS zero position, rather than simply using the geometry to mechanically self centre to the direction of travel like every car since 1900 odd.

EDIT: it isn't anything wrong with the geometry, it is a "feature" of the EPS system.  There is a motor directly connected to the steering column  through reduction gears. (So more steering effort goes through the couplings than a manual system, and a great deal more than a proper hydraulic one- I expect rapid failure of the couplings , but ho-hum...).
At low speed and small angles there isn't enough force from the self centring action to overcome the load of turning the motor backwards through the gears, so the EPS powers the steering wheel back to the known zero position to "help" the self centring. At high speeds the mechanical action alone is sufficient. No doubt all cars where the EPS motor is geared to the column do this, but I've never noticed with ones that have a steering rack, the vagueness of the Jimny system shows it up.
There must be a small "dead zone" to compensate for the natural play/slop in the system, the power kicks in when you drift outside it, so adjusting the steering wheel a few degrees has just pushed it out of the dead zone. My "twitch" happens at low speed, often in response to a bump in the road, I wonder if the suspension movement just nudges the steering out of the deadzone and I feel it the EPS kick in.

It might explain that "odd" twitching feeling that I get from mine.
I drive it like a Series LandRover, I just rest my hands on the wheel and let it go where it wants, only applying a slight correction when it is about to drift too far.
So when I unconsciously apply a tiny bit of steering to bring it back in lane, the ECU is acting to bring the SAS back to zero, and "kicks back" with a bit of extra force that I'm not expecting.

(The Plan being if I hold the steering input, the torque sensor detects that I'm holding the wheel and motors it towards the angle I set to reduce the input torque to a programmed level, this increases that level of "feel" that drivers expect artificially.
In the hydraulic system, you wind on some lock and hold it, and the mechanical self centring tries to straighten the wheels out, but as you are holding the steering wheel, the torque bar twizzles up and the power assistance kicks in to resist the self centring effect )

If it suddenly breaks, go back to the last thing that you did before it broke and start looking there :)
Last edit: 19 Jun 2024 19:53 by facade.

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