Vague steering at speed

[Blurredman]

For a while I've had very 'uncertain' steering at speeds over 50-60mph. The car has had a full alignment done twice, and it feels solid at slower speeds. But on the motorway or a fast A-road it wanders, seems to move left or right without steering input. Have had all joints and bushes checked, track rod ends are fine, tyres are new non-run flat Uniroyals and I've done about 1000 miles on them so they are bedded in. It's like there is no connection between the steering wheel and the front wheels at times, no sense of what is going on between rubber and road.

The car wasn't always like this. I've had it well over the speed limit on the motorway and it's been rock solid. But now I am scared to go above 60.

I don't want to do too much guessing, would appreciate ideas. Kinda taken the fun out of ownership tbh.

 

[B21]

Well if the geometry is ok,the tyres are ok..then it’s most likely steering components/ suspension..

Problem is the E89 design puts great strain on many of the steering related bushes..so if May not feel loose / defective to an inspection but it may be shot..if it isn’t a wheel bearing issue..

Unfortunately you are mostly into substitution..

I’d go with uprated tie tie ends..m3 linkages on the front..RTABs..

Does the ‘feeling’ happen under all conditions or things like corners, acceleration, braking, bumps etc?

 

[Blurredman]

Does the ‘feeling’ happen under all conditions or things like corners, acceleration, braking, bumps etc?

It's hard to pin it down. Under 50mph, it feels fine.
Under acceleration it's OK, until hitting the higher speeds. I'm tending to stick to the inside lane and avoid overtaking.
No pulling or instability under hard braking.
Then it's hard to be objective, but I feel like hard, fast left turns into corners the car is more solid than hard, fast right turns. That's when the steering feels the most 'unconnected' - but it's subtle, otherwise I'd immediately suspect a spring or damper.
Going over a very bumpy road at speed the car is not confident. I put some of this down to the softer sidewalls of the non run-flats. But as so many people swear by non RFTs I can't believe this is typical.

 

[B21]

What model is it? How old and how many miles..?

My 35is handled like a sloppy turd on a jelly…there was a little bit of wear in many components…

Decent non runflats should offer a marked improvement over the OE runflats..

 

[Blurredman]

What model is it? How old and how many miles..?

She's a 2014 20i with 51,000 miles on the clock.

Gonna have yet another look at the bushes and track rod ends, but nothing jumped out when it was on the ramp the last couple of times.

 

[B21]

What model is it? How old and how many miles..?

She's a 2014 20i with 51,000 miles on the clock.

Gonna have yet another look at the bushes and track rod ends, but nothing jumped out when it was on the ramp the last couple of times.

Hmmh strange not that powerful, not that heavy, not that old..not that much mileage..

 

[enuff_zed]

That’s enough mileage for shocks to be worn out. But to the naked eye they will still look fine and pass an mot.

 

[B21]

That’s enough mileage for shocks to be worn out. But to the naked eye they will still look fine and pass an mot.

Possible but N20 E89s are pretty light on their dampers..personally never seen a 50k E89 N20 struggle that badly on its dampers..come to think of it never seen a N20 E89 struggle once it was off run flats..

 

[Busterboo]

For a while I've had very 'uncertain' steering at speeds over 50-60mph. ...
Kinda taken the fun out of ownership tbh.

As I've written elsewhere, I'm lucky to live near quick roads, straight and bendy. In my experience, other factors - suspension & tyres - being right, the major element that keeps the fun in ownership is tyre pressures.

Drivers - and there are plenty - who wallow round on pressures lower than the ones BMW kindly provide at the bottom of the B pillar and/or who don't check them once a month don't know fun they're missing.

Some - the Drivin' Miss Daisy brigade - will complain, 'Oh, they're so hard! They hurt my pretty little botty' - and then never know the fun that can be had out of an E89.

What pressures are you on, Blurredman?

 

[Pondrew]

The car wasn't always like this. I've had it well over the speed limit on the motorway and it's been rock solid. But now I am scared to go above 60.

You mentioned on another tread that one of the little plastic 'deflectors' under the wheel arch was broken.
I wonder if that is enough to cause a bit of 'lift' on the front at speed? Seems unlikely, but that is all that has changed with car, by the sound of it.

 

[Blurredman]

You mentioned on another tread that one of the little plastic 'deflectors' under the wheel arch was broken.
I wonder if that is enough to cause a bit of 'lift' on the front at speed? Seems unlikely, but that is all that has changed with car, by the sound of it.

Yeah, it seems unlikely but I guess they fitted these deflectors for a reason. I've temporarily repaired the broken one (passenger side), will see if it makes any difference. Will be surprised, but as a process of elimination it's worth a go.

 

[flybobbie]

For a while I've had very 'uncertain' steering at speeds over 50-60mph. ...
Kinda taken the fun out of ownership tbh.

As I've written elsewhere, I'm lucky to live near quick roads, straight and bendy. In my experience, other factors - suspension & tyres - being right, the major element that keeps the fun in ownership is tyre pressures.

Drivers - and there are plenty - who wallow round on pressures lower than the ones BMW kindly provide at the bottom of the B pillar and/or who don't check them once a month don't know fun they're missing.

Some - the Drivin' Miss Daisy brigade - will complain, 'Oh, they're so hard! They hurt my pretty little botty' - and then never know the fun that can be had out of an E89.

What pressures are you on, Blurredman?

I'm running at 40psi front and rear at the moment, on Asy 5's.
Tyres are way beyond tech BMW tested 15 years ago or more, plus any deals they did with suppliers.

 

[Blurredman]

What pressures are you on, Blurredman?

This may muddy the waters a bit, as I am not running 9J's on the rear. You might remember my post from a while back, when I cracked my rears and decided to replace them with 8J's. I now have these pressures. I must stress - the 'vagueness' in the steering came BEFORE I switched to the narrower rear wheels and changed the RFTs to non-run flats.

So I have standard wheels and standard tyres sizes on the front, at the standard pressures. Should I be running a different pressure for non-run flats?

On the back I don't have a recommended pressure for the non-standard size (i.e. I don't know what the yellow boxes should read), so I'm running 37 PSI (the 255 tyres would be at 41 PSI OEM). Any thoughts on whether this should be more/less?

Cheers

 

[B21]

The rears should be around 32-36 psi…

To bottom out the issue I’d start at 32 rear and see how it feels..it’s not going to kill you..

 

[B21]

You mentioned on another tread that one of the little plastic 'deflectors' under the wheel arch was broken.
I wonder if that is enough to cause a bit of 'lift' on the front at speed? Seems unlikely, but that is all that has changed with car, by the sound of it.

Yeah, it seems unlikely but I guess they fitted these deflectors for a reason. I've temporarily repaired the broken one (passenger side), will see if it makes any difference. Will be surprised, but as a process of elimination it's worth a go.

Aerodynamic effects don’t tend to have any perceptible impact until your past 60-70 mph…really 90 mph plus for significant effects..

 

[Pondrew]

I hear a lot of "try different tyre pressures" on car forums.

Not a fan TBH. Remember that the specified tyre pressures are for one reason only, really.....to support the weight of the car properly and efficiently. The entire weight of a vehicle is supported on 4 round 'bags' of air. Manufacturers don't specify pressures as a 'guide', they are there for a very good reason.

That is why manufacturers specify different pressures for different loadings; 1 occupant, 2 occupants plus luggage, etc. It's all about weight.
OK pressures may alter a little if the wheel/ tyre sizes change significantly but that is due to different set-ups having different amounts of 'room' for the air in the gap between the tyre and wheel.

 

[Busterboo]

The rears should be around 32-36 psi…
To bottom out the issue I’d start at 32 rear and see how it feels..it’s not going to kill you..

Miles off! MILES off. For quick driving, try 36R/44F. For 'normal', no lower than 32F/40R.

That said, your odd wheel set-up will/may/could - I don't know - skew things.

 

[matsmith749]

There is another forum where a ton of pressures were tested on non-run flats & the consensus was 34 psi front / 38 psi rears (standard tyre size obviously) on the 35is with 19" wheels.

There are no quoted BMW figues for non run flats - only the RFTs that are standard fit, so the figures in the book / stamped inside the door (or wherever) are not much use to you.

Any figure you see online (including here) is just made up with a touch of trial & error.

 

[Blurredman]

There does seem as much art as science when it comes to deciding on tyre pressures! I'd assumed that BMW recommended pressures for my front (standard) wheels with RFTs should hold true for non-RFTs, but am now tempted to run them with a little more air in them and see how that changes the handling.

For my non-standard rear wheels (19" 8J) I have 235/35 non-RFT tyres running 37 psi - and that is just guesswork, 'cos few people have this configuration. On reflection I might have been better off with 235/30 tyres, but I can't believe it makes much difference and surely the steering 'feel' is way more influenced by the front wheels/tyres than the rear? But I think I will eek the rears up +1/+2 psi too and see what happens.

:driving:

 

[JoeZed]

What Tyres have you got on the car ? How old are they ? A few hears ago, I put on new tyres - Run Flats - can't remember the brand but anything over 60mph on them the car felt like I was towing a a caravan in a cross wind. It felt like the rear of the car was constantly snaking. Also tram lined like hell. It took about 3k miles for the tyres to come right. Now I'm back on Conti's non run flat the car is very stable.