Vague/ notchy Steering problem

[Blatto]

Had my ST-Line X 140 from new (2019) model. Has been running perfectly until I had a service a few weeks ago. Currently on just over 17,000 miles on the clock.

Standard 18000 miles or 2 years service as per the Ford Schedule at a local Ford dealership I have been using for the past 4 years. No problems were flagged up during the service, tyres were about 6mm tread depth (5.5 on inner edges at the front) and about 6.5 mm on the rear with even wear. Basically they changed the oil and filter, checked everything was as expected and handed it back to me.

The week after that was a fairly windy one and as per normal it was a bit twitchy on the motorways with the strong side gusts but nothing unusual.

However since then with the winds back to virtually nothing I have a strange handling/steering Issue. It feels very vague and twitchy when trying to stay in a straight line on the motorway, seems to want to follow every contour of the road and there's a strange central notch to the steering. 

Hard to describe really, but with the wheel dead straight there is a point where it is solid and stable, but moving the wheel just a fraction (feels like 1 mm either side) and it suddenly feels very light.

Feels like there is a notch dead centre that you have to overcome then it's too light, i.e. none of the increased resistance you get with increasing speed.

I checked the tyre pressures which I do on a weekly basis anyway and I always have them at the recommended 33 front and 26 rear for light loads under 100mph. Seems the garage had set them to 35 front and 35 rear, so readjusted them to the normal 33 and 26 . It felt a bit more stable but still with the notch at the centre and not as controllable as usual.

Seems very floaty at motorway speeds but not noticeable on the twisty 60mph country lanes.

I checked the wheel nuts were all done up to the correct torque and didn't find any that were loose.

I've never hit any kerbs or pot holes since I've owned it, spends most of it's life up and down the motorway at 70 ish.

Many years ago I had a Toyota MR2 which was a bit twitchy in a straight line, turned out to be worn dampers but I doubt that my Fiestas ones are worn out in 17,000 miles of normal road driving.

I have spoken to the garage and they want me to take it in for a check but due to the current Covid situation I can't get a courtesy car so would have to take a day off work, unfortunately I don't have any days holiday left to take. 

I get the impression that it's not a mechanical linkage/shocks wear issue but more to do with the electronic steering assistance.

Anyone have any ideas or experienced anything like this before?

 

 

 

 

 

[Luke4efc]

Have you got the lane keep assistance turned on? If so I'd turn that off and try again.

[Blatto]

Yes I always have that off, but I checked in case they had turned it on at the garage, but it's definitely off.

I did turn it on to see if it was still working, which it is, but it's the same with it on or off.

 

[st line x 140 driver]

could be track rod ends.

[Neb_engineer]

I would check the wheel alignment, i had a similar thing, the force of me fighting side winds at motorway speeds on my fiesta caused the wheel alignment to change

[st line x 140 driver]

There is, perhaps, an ever-so-slightly elastic, compliant feel to the car’s power steering that we don’t remember being present in the last Fiesta, 

https://www.autocar.co.uk/car-review/ford/fiesta/ride

might just be character or dare i say it garage kerbed it!

[Blatto]

I know the garage didn't kerb it as I stayed with the car while they did the service. Normally I would get a courtesy car and go off to work and pick it up on the way home.

But due to covid restrictions they are no longer providing courtesy cars so I stayed at the garage and could see them working on my car from where I was sitting.

Prior to this vehicle I had a MK7.5 ST-Line 140 which although it had great handling, it was a bit twitchy on the motorway in comparison to the MK8. The one thing I noticed when I got the MK8 was that it was a more stable cruising experience. Now it feels worse than the MK7.5 was and has a definite notch in the middle as I described.

Took the wheels off this weekend and switched them back to front, will see how that feels on my commute next week.

 

[Blatto]

Well lesson learned for me, solved this one.

It was my tyre pressures. I've been using my trusty old guage for the last 20 years or so and it's been fine.

Turns out it's now over reading by 3psi so I've been driving along with the fronts at 30 and rears at 23 psi.

That's sort of explains why I thought the garage had over pressured them although it doesn't excuse them for putting the rears on the same psi as the fronts.

I borrowed a guage from a guy at work and it wasn't agreeing with mine so I got a TireTek one from amazon which claims to be correctly calibrated to some standard.

Pumped them up to the correct 33 front 26 rears as indicated by the new guage and just took it out for a drive. Huge difference, back to normal now.😀👍

Seems this car and tyre combo is pretty sensitive to tyre pressures being spot on. I've had cars in the past that 2 or 3 psi was hard to tell.