[W126 Coupe] Wheel Shimmy Driving Me Crazy!

[Alexander Hochhausl]

Hey All,

I've had this problem on my 89 560 SEC as well as my 81 380 SLC. I'm
thinking some of you must have also. 

There is a vibration, hopping or shimmy - hard to describe, but
definitely from the front end at between 60-80 MPH, but not always.
Sometimes more than other times. I can feel it in the steering wheel,
but more so in the body. More when driving straight, less when in turns.
In the summer it's not so bad, but now it's getting cold and definitely
more pronounced.

I've replaced the steering idler arm assembly, all the rod ends, and a
number of bushings on the suspension over the years but still the same.
I keep thinking it's steering related. The driver side front wheel is
solid as a rock, but the passenger side, with reasonable effort, I can
swivel the wheel slightly - I think it is more than it should be.

I've had the tires balanced and rebalanced. Same thing, even when I
rotate the tires. I'm thinking a harmonic builds in the passenger wheel
due to that slight bit of play, and builds with the speed.

Am I barking up the wrong tree? Is there another bushing or something I
am missing (Oh, I replaced the shocks too - no change). 

I have to say, I love the car, I drive it like crazy, but this is
driving me crazy. Any thoughts anyone?

PS. (from the discussion of air pump and EGR valve): I just got my car
inspected. Emissions were CO - practically none, HC = 25. The mechanic
said it is unbelievable how low my emissions are. I think his machine is
broke, but I'm curious, how does this compare with your readings. I have
messed around with the mixture and other things (due to supercharger
mod). And these readings are with no air pump and no EGR. 

Thanks in Advance Ladies and Gents.

Alex H

89 560 SEC (Supercharged)
81 380 SLC