The W123 (and W116) have more roll oversteer designed in to unload the
outside front tire in heavy cornering. On the W114/115 chassis, you
can unmount that tire due to excessive side force, usually causing a
severe accident as the car becomes uncontrollable. Lighter rear sway
bar, I think. Gives a "swoopy" feeling and some rear lift under hard
cornering, mistaken for poor handling.
Better than the jacking you get on the older swingaxle rear ends,
believe me! THAT'S a surprise!.
Benz also has slightly "numb" center feel -- this is deliberate, often
referred to as "sneeze insurance" -- you don't want to flip the car on
the highway at 125 mph because the steering is so senstive that you
change lanes (or worse) if you sneeze!
I find the Volvo to have much "tighter" steering -- to the point it's
oversensitive on the highway, leading to excessive sideways motions.
With the front end tight on the Benz, you can change grip on the
steering wheel without swerving around, too.
Jack on front wheel off the ground and check for steering play. If you
can move the wheel by grasping at 3:00 and 9:00 and pushing with one
hand and pulling with the other, you have something loose, most likely
tie rods and drag link joints. I would suggest simply replacing both
tie rods complete, the drag link, and steering damper all at once.
Makes a huge difference, believe me. Also check the idler arm -- any
vertical play and the bushings are shot.
Excessive play at the steering wheel can be a worn out coupler - they
are only $100, and make a HUGE difference. You will get some clatter
of the wheel on rough surfaces or gravel if this is the case. If the
coupler is good, you can try to adjust the steering box, but it may
need to be rebuilt.
They aren't sports cars, for sure, but the steering should be smooth
and precise, no slop.
Peter
