I think this is the case for my 300D. Sometimes it feel OK, like on the freshly paved freeway just before the turn pike. But then on some parts of the turn pike, you can feel the road dip up and down/left to right in the steering. Just like your two motorcycles setup analogy.

I am not sure what to do about it though. If a spreader bar is required to ensure a PROPER alignment I think my only recourse is a dealership alignment. They are $125. I'm OK with paying that so long as they ACTUALLY do a good job.

I particularly don't like the shop I go to currently, but they are the only other place in town that will do a MB. Sears and the other places won't touch them.
I forget what the incident was but they were having trouble do something on my 190E and blamed it on wrong parts, which I personally installed. I do not install wrong parts....

I did a DIY toe alignment at home with thread stretched between two jack stands and for the spreader bar I had 2 pieces of 2x4 lumber and a bathroom scale on either side of the jack - you may need to support this contraption.

I set the toe to equal distance and just a smidge more for wheel to point inwards. Car is rolling pretty good. For absolute correct alignment, the dealership should have the 5 finger spider that go into the wheel holes (the small holes between the lugs) so they actually measure from the hub. They should also use the spreader bar and follow the correct setup technique in which toe is set last.

Gah driving up today was horrible.

To me, it feels like the car is overly sensitive to the road surface. I felt like I was micro-managing the steering wheel, correcting it way more often than I should.

I am going to call the dealership and see if they can do it properly? Is there any specific questions that I should ask to make sure they are not full of it? Should I ask if they use a spreader bar? etc?

Are you ready to try and do the job yourself yet?

Ahh not quite! Too cold here still. I don't mind paying, so long as the job is done right. I've always been leary of going to the dealer as they were more expensive but the more I thought about it they're only $125. I paid $98 for the last alignment. $25 difference isnt bad especially if the job is done well/correct.

I don't know if they've started this in the US but over here some Mercedes dealerships have started specialising in classic 'Benzes - apparently these particular dealerships are better suited to our needs.

Failing that you should ask to speak to the chief mechanic - the guy at "my" dealership is really knowledgeable and very helpful. Get past the high pressure sales desk and you should hopefully find some real people who will help. The extra money that you pay should be worth it.

Beware of dealers and call around first. One nearby that claims lowest labor rates in the area charges $198, while another charges $98.

There are not too many within 30 miles or so of me. The one closest (6 miles--right most dot on link below) said $125.

Mercedes-Benz dealers in zip code 44446

All the other non-dealership places in there area...two said they could do it.. One I've been going to and am not too terribly pleased. The other we used once and they were OK. They are only open weekdays which makes it impossible as I work lol.

get your cars alignment specs from ps2cho website and note them down, make sure that the model they put in is 124.128 for your car not W126 all models as your original sheet shows.

If your alignment place does not have a spreader, they can substitute for a human spreader bar (usually a tall strong chap) to push the wheels apart. The toe is then set - this should be the last job tho.

I DIY and got it quite OK. Im going to roll down to a nice toyota shop that has a nice hunter machine and ask them to check it for me.

Did you set up the caster and camber too? Did you start a thread on this? {If so I missed it sorry}

With your home made spreader bar do you feel that the force you apply is more or less the force needed to get the front wheels to spread with out pushing too hard on the tyre side walls?

the spreader bar force applied is about 65 kg - the reason to use scales in between is to give some cushion whilst adjusting the toe.

I did not setup camber or caster as I did not know of a way how to measure caster without actually measuring from the ball joint clamp itself. Im thinking of making something from wood for this purpose. - That may cause a sign to be plastered on my forehead one morning saying 'obsessive gear head' or something.

On a W123 the spreader force is 110N - 120N which is about 11 kgf

I wrote up a procedure for the caster and camber adjustments here if you are interested

http://www.peachparts.com/shopforum/diesel-discussion/284337-how-i-adjusted-toe-out-camber-caster-my-w123-300d.html

(Yet again W123 based information => 1st gen W126 is about the same though)

man, I need to check spelling before posting - I lost the decimal

nice DIY,

to measure the caster on a w124 and 201 a U shaped piece is hung on the hub carrier and ont he ball joint clamp nut according to the FSM - it takes its measurement from a scale that is printed onto it.