vague feeling / instability

[Merlin The Benz]

Hello people. . I have an '06 E320 CDI estate. I never been 100 percent happy with the feel of it. The steering appears to have little to no feedback or castor action at low speeds with a very vague feel... at high speeds it feels twitchy especially in cross winds. Last wed coming up the m40 in the wind it felt like driving with a snaking trailer. The car has been to a tyre centre who claimed it was correctly aligned... the front tyres have done 20k with me and might have very slightly more wear on the inside but nothing significant. It has been to a local German specialist who suggested all was fine..... I came from a saab 95 areo hot which I would happily take my hands off the wheel at 90... in Germany. . This car I would feel uncomfortable taking my eyes off the road at 70 never mind hands off the wheel. Is this normal? ... does anyone have any suggestions or ways of improving if it is normal..? Any suggestions gladly accepted... Thank you...

 

[wheels-inmotion]

Has the castor positions actually been measured or just the tracking?

 

[Merlin The Benz]

Thank you for the reply...
They did a 4 wheel lazer dot line up but not sure if the castor position has been checked. I am guessing that would be a good place to start?

 

[GordonTarling]

The best place to start would be to get all suspension bushes and joints checked for wear. Then, when you know for certain all is good, take it to a specialist like WIM for a full 4 wheel alignment check.

 

[Merlin The Benz]

Thank you. I did take it to a independent specialist with the complaint and I believe they checked through bushes etc and they suggested all to be well so might be time for WIM.

 

[Merlin The Benz]

Once again looking for advice. ... I tried to get my local indy Merc chap to do a 4 wheel set up. .... he suggested the none merc aftermarket wheels currently fitted had the wrong offset and that it was a waste of time aligning until I had the proper Merc ones..... The local alloy wheel supplier says it shouldn't make that much difference..... standard wheel is 7.5j on a 42 offset... current wheel is a 8j on a 30 offset... front and back... Does anybody know if this would affect stability at all? Once again any help or advice would be welcome I seem to be going round in circles with this one!... Thank you..

 

[a111r]

My first Merc was a '94 E300TD. It felt utterly shocking to drive at speeds over 50 mph, much like yours.
About ten quids worth of ARB mounting bushes transformed it.

 

[grober]

When cars start to "self steer" the obvious place to look is at the front suspension and steering . However the 5 link rear suspension is quite complex and adds considerably to the cars overall stability. Has anyone looked at the rear suspension settings and rear subframe bushes. If they are badly worn the rear of the car can start "steering" the front?

 

[Rory]

I came from a saab 95 .....

You might have other problems to do with the wheels and possibly suspension bushes, but I came to my car (when it was 5mth/6K miles old so nothing worn out) from a series of front wheel company drive cars and I've never felt the car inspired confidence. The word I usually use is that the car just doesn't feel "planted".

I don't drive many other cars so thought it could just be a FWD/RWD thing, but I've driven 3 Series on odd occasions and they always immediately feel much more composed.

 

[Merlin The Benz]

Thank you all once again.... lot's of avenues to check there...

 

[LTD]

20k miles on the front tyres ?

What is the tread depth ? I suspect they are the culprits.

Don't overlook the obvious .........................

 

[wheels-inmotion]

Incorrect off-sets can make the steering feel twitchy because the scrub radius is moved away from the lower ball joints pivotal point but the off-set would have to be a dramatic change which yours isn't.

 

[Merlin The Benz]

Thanks again... the 20k is mostly motorway over the last 18 months so tread depth is probably better than you think certainly not down to the warning bars yet... although to be fair they are budget tyres fitted by the sales outlet so may not be helping the cause... Mr WIM I am down your way next week so will try to make an appointment. Thanks again everyone. ..

 

[m2mb]

"at high speeds it feels twitchy especially in cross winds"

An estate obviously is catching so much more wind than a saloon. Imho just maybe the solution would be to drive below 70 mph in cross winds. My w211 tracks well at any speed but in severe winds I slow down really. My previous cars never tracked so well even fwd.

As wim said caster adjustment can improve stability but steering will become heavier.

If no component or set up is faulty then probably you need better tyres with more sidewall reinforcement. Stating the obvious, higher speeds require higher pressures in the tyres.

Did you check rack for play? With car in park and engine running turn the steering wheel slowly, if the wheels do not move by the time the steering wheel has moved by about 10 mm, you have steering rack play.

 

[a111r]

I had a 210 that came with 'Accelera' budget tyres fitted - real rubbish.

With decent tyres fitted the car was transformed.

 

[Merlin The Benz]

Thanks... I would say I have about10mm of play or maybe a bit more... the steering does feel overlight and would benefit from weighting up a bit.... and I did have accelera on the front which I was awaiting an offset answer on before I turned them into proper tyres... I think the cross wind is just hi lighting an underlying problem. I drive several vehicles on a daily basis including a 7.5t box van a Renault Master panel van and a 2000 discovery 2.. the E class is the most twitchy and insecure feeling of them all... I am pretty sure that shouldn't be the case... I will follow up all advice and hopefully see a result... Thanks again people..

 

[Merlin The Benz]

Well today I let WIM wave their magic technician over the benz... 3 x castor /camber bolts later... oh my life what a difference... ok so maybe still not the most stable car I have driven but wow... its a different animal to the one I took there.. It will now travel in a straight line without fighting itself... I can look down for the rear wiper switch without ending up on the rumble strip.... and in the high winds of early today it behaved like a grown up car should.... Thanks everyone for your help and advice here.. Think you can stamp this one sorted...!