Steering shaking at speed - not wheel balance

[bstark]

I'm not sure why I've put up with it for so long, maybe it has gradually got worse over the years, but at motorway speeds I get a serious 'out of balance' style steering wheel shake.

 

The wheels have been checked and are balanced.

 

The thing is, you can't drive through it so it doesn't lessen or disappear with more speed.

 

It does, however, come and go, and it tends to be either there or not (not a sliding scale of severity). Pretty certain it isn't road surface related and am getting the feeling it is more to do with what the wind is doing.

 

Hence I've been wondering if it's aerodynamic and down to the cycle wings? Does this sound likely? And if so is it a case of TADTS or is my car just 'special'?

 

I've owned the car for 12 years or so but didn't build it. There is star crazing around the wing mountings on the left hand wing (car over 20 years old now) whilst the front mountings on the right hand wing could be tighter (they don't exactly rattle though, and are also seized).

 

Anyone experienced and cured this?

 

Bob

[Stationary M25 Traveller]

Have you checked the wheel bearings, top and bottom wishbone pivots and track rod ends lately ?

[IanJ]

Have the wheels been balanced on the studs or the centre holes. Mine can be balanced to 0g on the centre holes, but will be as much as 20g+ out when checked properly on the studs...

[Stationary M25 Traveller]

Another thought ..... when I bought five new Toyo T1-R recently and had them inflated to 18psi the fitters were chasing their tails trying to balance them. They were all over the place. They realised they were flexing ..... so increased the pressure to 34psi. Then balanced fine.

 

Reduced the pressure to 18psi for use ..... work fine.

[bstark]

Interesting...

 

Almost certainly were balanced on the centre holes...

 

Bearings , pivots, track rod ends etc. went through the mot fine recently and the car feels a as planted and direct as you would hope so I haven't specifically checked them, no.

[Harry No Sheds Flatters]

A few questions:

 

Does the vibration occur with the same wheels or with different wheels/tyres?

 

If the four wheels are the same size have you tried switching the front to the back?

 

Were they balanced and checked at the same place?

[Z3MCJez]

Sounds like bearings or discs to me. I had a set of new discs that weren't round a couple of years ago. At 110+ (track, where surface is smooth) it became unbearable. New discs cured it.

 

That bearings passed MoT doesn't guarantee that they haven't got play that feels bad at motorway speed.

 

Jez

PS my experience is that 20g out of balance is not enough to notice at up to 100mph.

[CharlesElliott]

Hub failure (i.e. bearings moving in the hubs) can also cause this - relatively common with the aluminium hubs, especially if the bearings aren't done up tight originally. As the bearing moves against the race, the race wears the aluminium until the races themselves start moving around.

 

Edited by - CharlesElliott on 6 Jul 2013 20:49:34

[Grim Reaper]

I've just had the steering rack out to replace the gaiters as they were starting to crack and as part of the exercise I took the opportunity to 'correct' the wrong rack height that is supposed to cure bump steer. I added a couple of spacers under the existing rack mounts that were made up from some 10 mm thick alloy bar.

Now imagine my suprise that there is now an eerie lack of steering wheel shake when I took a test drive afterwards. The poor roads in town that used to kick the car all over the road even at 30mph now drive like they were smooth as glass. It's weird, I can see the bumpy road surface ahead but the steering wheel no longer shakes when I drive over it. I can't wait to try a longer test run on some of my favourite roads.

Now just maybe the problem you are experiencing is the result of the same incorrect rack height, and small road imperfections, possibly coupled with worn shock absorbers, are creating bump steer which you feel as wheel shake.

Do you have thicker lower rack mounts already or not ? (mine were the same sized upper and lower mounts)

It's been like this for 10 years, wish I'd fixed it sooner.

[bstark]

Grim reaper - this isn't what occurs with mine at all. Poor road surfaces are fine and there is no bump steer. This is purely at speed and can occur on newly laid surfaces that otherwise feel smooth-as.

 

Jez, Charles, is there an easy check I can do for the bearings without specialist tools?

 

The discs are a thought as well.

 

Swapping the wheels around us of course easy so will try that.

 

I take it the general consensus is that it is unlikely to be the cycle wings, then?

[Harry No Sheds Flatters]

I take it the general consensus is that it is unlikely to be the cycle wings, then?

 

Highly unlikely.

 

I doubt it will be the discs unless this only occurs under braking

[Tony Whitley]

My old car suffered from an intermittent rattle that I couldn't track down. That turned out to be slight wear in the steering rack ball joints that I presume transferred and amplified road noise to the whole chassis. It was noise more than shake but it's something else to check.

[CaterBram]

bstark, just noticed that in your sig you've go "Supersprinter"

 

you've not got a live axle have you ? as your talking about the car being over 20 years old.

 

I'm sure you've checked for the normal live axle bearing slide.

 

But i've recently had two issues which did show up as similar vibration.

 

A rear half shaft bearing which whilst had not failed was on the way, and also had a slightly bent half shaft.

 

Edited by - CaterBram on 7 Jul 2013 11:14:22

[Z3MCJez]

Quoting bstark: 

Grim reaper - this isn't what occurs with mine at all. Poor road surfaces are fine and there is no bump steer. This is purely at speed and can occur on newly laid surfaces that otherwise feel smooth-as.

 

Jez, Charles, is there an easy check I can do for the bearings without specialist tools?

 

The discs are a thought as well.

 

Swapping the wheels around us of course easy so will try that.

 

I take it the general consensus is that it is unlikely to be the cycle wings, then?

 

Jack the car up, hold the front wheel at 12 and 6 and try to rattle the wheel. If it moves at all there's your problem. You may be able to tighten the bearing but as Charles says, the hub tends to go first.

 

Jez

[Grim Reaper]

Another guess then, low tyre pressures causing a flat spot when stored for a while, resulting in vibration when first used, if storage period is not so long, less of a flat spot, no vibration next time it's used.

[bstark]

Thanks Jez, will try that.

 

Caterbram, yep it's a live axle that's had a lot of money spent on it and was completely rebuilt a couple of seasons ago with new bearings, a new half shaft when a stress crack was found, and is now baffled to within an inch of its life, as well as a check on the CW&P and the ATB

 

Tyre pressures would of course be easy to sort - it did sit for a long time this winter but as I said this has been an issue I've just lived with for years (for some reason )

 

Bob

[CaterBram]

In my case i'd caught a kerb wrong with the passenger side rear, did not feel anything wrong at first, but got a small vibriation, however wheel wobble when viewed from the rear became plainly visible. on that side there was no slop in the bearings be definitely a wobble which got gradually worse. Fitted new half shafts as part of a rakeway upgrade and solved the vibration.

 

And mine had been refurbed only a year before..

[bstark]

If it hadn't been doing it to a degree before the refurb I'd be getting more worried for my wallet

[7 wonders of the world]

when you had the wheels balanced did the guy:

 

a- know how to use the kit properly - checking rim width offset dimension etc rather than guessing and punching near enough numbers into the balancer, and worst still double balancing the wheel 😔

b - has the machine been calibrated, usually this can be done in house with a calibration weight.

[Pendennis]

toe out?

[bstark]

7 Wonders - no idea but they've been in business for years and I haven't had a problem on the rest of the fleet (same fitters).

 

Pendennis - pretty certain mine is set for zero toe out

 

 

[bstark]

Thanks for all the suggestions.

 

Gave the car a good going over last night and have ruled out hub/bearing, track rod ends, steering rack and mountings, stub axles.

 

Swapped the wheels around so will see if that helps when I take it back on the motorway later. Hopefully it's a simple as the tyres going out of shape whilst standing over winter and a new set of boots will cure it.

 

Bob

[tbird]

surely though you have fitted new tyres "over the years" but you say its always done it

 

Tim

[Myles]

That bearings passed MoT doesn't guarantee that they haven't got play that feels bad at motorway speed.

 

My thoughts too - and possibly more so for rod ends etc. where things are more 'solid'?

 

As an aside, I've never noticed any flat spot issues over winter/layup - and one of my two sevens has only made it to the mot centre and back over the last couple of years (this one excepted - it's in the hotel car park right now!) and so would be a good candidates for this sort of thing.

[bstark]

Well so much for my confident assertion it isn't wheel balance I've never had a wheel balance vibration before that you couldn't drive through with more speed.

 

Swapped fronts and backs and whilst still slightly there it's a massive improvement and all but gone.

 

As I said it's always done it to a degree, and with different wheels and tyres. It had just got so bad recently I finally resolved to do something about it.

 

I'm kind of confused now but will bung a new set of AO21s on (these are getting on a bit now), watch the guy balancing it like a hawk, and then take it from there.

 

Cheers for humouring me everyone.

 

Bob