Handling

[RHD]

Help - please!
I have owned my stunning W126 420SEL (1991) for a couple of years now but for most of that time it has handled very badly.  

Basically the car goes 'soft' when on a motorway or driving predominantly in a straight line.  The steering feels light and inaccurate and the car rolls a lot!  
However the problem can be temporarily cured by holding the wheel tight around  a light curve when the steering noticeably 'firms' up, is heavier and much more accurate.  The roll also disappears.

I have changed: all steering and hub joints/bushes, 4 shocks/tyres, steering damper and even tried another (used) box.  None of which made any difference.  CAstor camber also been adjusted.

Having tried 'everything else' should I invest in a new steering box - this being the only component at the front that is not new!  Do boxes wear so that when adjusted they seems okay until on the move?

Many thanks in advance.

 

[mhannaford]

RHD
Power steering in the straight ahead position
has almost no assistance. As the turning becomes
tighter so the assistance kicks in.That's why you
feel float going straight and it all firms up on the
turn. But quite what that has to do with roll defies
logic (or does someone know better?)
It could be that things change when you power round
a corner rather than just coast round but you are not
aware at the time just what you are doing.
Although I have no personal experience of box
adjustment I have heard it said that adjusting it
gives a false impression of having tightened it up
but in fact it hasn't
Good luck, maybe Andy has some knowledge of this
Mark Hannaford

 

[RHD]

Many thanks for your thoughts.  

The problem is constant - power does not effect it unfortunately.  The tightening up is felt in both body control and steering weight and accuracy.  Weird!  

I am hoping that the false impression you mention by tightening the box is what I have suffered with both boxes I've tried.  

Club HQ suggested Andy as well!

 

[Andy]

Hi

You don't mention how many miles the vehicle has covered. But it more than likely the steering box worn out. You have fitted a recon one. When the owners magazine comes out this month you will see I have mentioned the only way to get satisfactory results is to fit a new one from MB. Problem is that the parts that wear don't get replaced as they make the box uneconomical to repair. So really you buy the same problem again. I will admit it may not be so servere. Especially if its and old 123 (nothing wrong with 123's before any body  says anything grew up with em)done a million miles. Then you think its the beez neez. But I think the result your looking for will require a steering box. And I think they are quite expensive. You probably would of half paid for it if you saved the money from the parts you fitted. (Sorry its an on going thread on this forum about fitting parts which are never going to cure the problem). Anyway I hope I have been some help.

Regards
Andy @ www.mercedesservicing.com

PS. As an aside for those of you reading this forum. In my experience, unless the shock absorber\ damper is leaking on the rear. They hardly ever need replacing. The fronts is another thing. There the ones that get a real pounding.

Very rarely do the 124\190 front shocks ever leak. They pass mot's. But if they have done over 100k. Then I would suggest if you want to spend some money on your vehicle and get some USEFULL benifit rather than changing stuff which ain't going to cure your problem. Then fit a new pair of front shocks. You will find the ride and handling vastly improved. Fit BILSTEINS. There OEM. They will also improve the stoping distances. This is just a suggestion. Take it or leave it. We don't sell shocks so I have nothing to gain. But you WILL feel the difference. This applies to most of the mercs.

Good luck & may the force be with you.(Just watched Star Wars)

 

[RHD]

Many thanks for the reply.  As I have feared fo the last 18months!  

Car has done 130k.

Second box I put on was a second hand one - don't know how many miles!  Presumably if it also was old it might suffer the same problems.  Both appear to adjust okay with spare threads, one has a lump but both feel the same!

What part is it that they do not replace?  Can you buy that part and have your own box rebuilt?