Squirrely handling 190 E front end alighnment help?

[Mel Weaver]

Help! The garage has replaced idler arm, and tie rod, car pulls a little to pass. side (needs alignment?). Car was very "light" feeling at speeds over 60mph, before the changes- still very bad at speeds over 60. Will alignment help? Everything seems O.K. to the garage. It was closed before I found it still bad at speed, wondering if I should make Appt. Mon. for alignment or may be something else? I saw him jumping on front end checking shocks/struts.
Any ideas?
Thanks for support- Mel

[ILUVMILS]

If you've replaced front-end components(especially tie-rods)you need to have the alignment checked. Once this is done you can re-evaluate the cars' handling characteristics. Good luck

[Mel Weaver]

Thanks- bringing Her in Mon. for alignment-will keep you posted!
-Mel

[Duke2.6]

If steering components are changed only the toe setting is potentially affected, not camber or caster, so assuming the car drove okay before the steering components were changed, you only need to have the toe setting checked and set to spec. You can do this with a carpenter's tape in your garage if you wish.

I do all my alignment with a tape and inclinometer. Since the 190E 2.6 is front heavy (about 57 percent) I set the cam bolts in the lower control arm to achieve maximum negative camber and maximum positive caster, equal on both sides. This yielded about -0.75 degrees camber and +10.5 degrees caster, which reduces understeer. Toe-in is set to about 1/16" and there is no adverse tire wear.

Duke

[haasman]

Mel,

Sounds like your toe-in is off. Was the alignment done with a spreader bar? This should always be used in conjunction with an alignment it that it duplicates the outward thrust action your front wheels do when driving.

You might also want to check the rear suspenion thrust links. These can cause a wandering feeling, especially at speed.

Have you replaced your front and rear sway bar bushings? Although these probably are the reason for your handling problems, they are inexpensive and easy to do (DIYer job) and make a difference in flatter corning and transitions.

Keep us posted,

Haasman

[suginami]

I agree with Haasman.

Stu Ritter in the Star Magazine has written about the rear suspension thrust leaks, before.

When worn out, they can cause exactly the symptoms you are experiencing.

[haasman]

Paul

I am sure you meant "links" in your post above?

Haasman

[suginami]

Yeah, I meant "links". Freudian slip. Must've had to take a "leak".

[ILUVMILS]

Duke2.6, if you've ever done an alignment on a Benz you know that camber, and to a lesser degree, caster, changes when the toe is adjusted! I've done hundreds (literally) of MB alignments on several different types of alignment equipment over the years, and I can't recall ever doing a toe-and-go. Sorry to dis-agree, but I wouldn't trust a tape measure (and the human error factor) when it comes to my Michelins.

[Duke2.6]

If only the steering linkage components were changed then only the toe setting can be affected.

Camber and caster is only affected by changing control arm or strut components.

Of course, changing camber of caster will also affect toe-in, so in any alignment operation, toe is the final adjustment after camber and caster are set.

I've been doing all my own alignment in my garage for over 20 years with an inclinometer and tape measure. It's a bit lengthy and tedious, but I get the alignment settings I want, which are often different than OEM spec. I also keep tweaking the tie rods as necessary to get the steering wheel dead on straight when cruising in a straight line. Alignment shops are particularly bad at this, but it usually take one or two 1/16 turns of the tie rods and is somewhat iterative, so it's just easier to do this myself.

I got my MBZ dealer to put on my 190 on their modern computer alignment machine after I had reset the front alignment and it was within 0.1 degree of my measured caster and camber settings and 0.5 mm of my measured toe-in.

Duke

[ILUVMILS]

Hi duke2.6, the next time you get a chance to get your MB on an alignment rack, try adjusting the toe while watching the camber setting. It changes. A lot! The reason for this is the amount of positive caster that MB specifies. I'm not challenging your methods, but unless you can see ALL the settings while you're adjusting the toe, you wouldn't be aware of this. For what it's worth, I applaud your ingenuity, but I have one question. How do you know what what your caster reading is?

[Duke2.6]

With a strut or contol arm suspension, the camber and caster are established by the location of the pivot points in 3D space. The steering axis allows only one degree of freedom and rotating the wheel from the straight ahead position will change the camber reading, but this is due to the effects of caster. Of course, when reading true camber the wheels should be pointed straight ahead. As the wheel is rotated about the steering axis, the camber reading will change. In fact, this is the way caster is determined!!!

I'm posting a copy of an e-mail reply (edited slightly for clarity) to another forum member who queried me this morning about how I align my cars.
BTW, I'm a retired automotive (GM) and aerospace engineer, and I've been road racing since the sixties (cut my teeth in a '63 Sting Ray) doing most of my own engine/chassis tuning/overhaul and modifications as required/allowed.


"You can use the inclinometer to measure camber directly by laying it against the tire or wheel flange. To measure
caster you take camber readings with the wheel at the left and right steering locks and the arithmetic difference is
the caster. Getting the sign correct can be tricky, especially on cars with near zero caster settings, but Mercedes
typically have high positive caster settings, so the number will always be positive. If you are patient you should be able
to read the inclinometer to less than 1/4 degree, but it can take repeated readings until you're consistent. As with
most things, competence comes with practice.

As an example, on the LH side, positive caster is indicated if the camber reading at full right lock is less than
the reading at full left lock, such as -3 and +7. The caster is 7 - (-3) = +10.

To set toe, mark the measurement point on both tires. Start with the marks at the rear and measure, then roll the car forward and measure with the marks toward the front. Align the marks as high as possible from the ground without the chassis interfering with the tape. Tires with straight circumferencial grooves are easiest to work with. With the
steering wheel straight sight down the tires to visually confirm that each has about equal toe in. Equal length tie
rods is also a reference check. I usually have to tweak one tie rod to get the steering wheel dead center when
traveling in a straight line after the initial test drive.

It's a somewhat lengthy and tedious process to do it this way, but I got tired of dealing with alignment shops that
wouldn't align the car to my specs and did not understand geometry, so I haven't seen an alignment shop for
about 20 years. I do experiment somewhat with different settings, but once I get alignment dialed in to what I feel
is optimum for handling, the settings hold indefinitely. As I said, on a W201 set the cam bolts on the lower
control arm for maximum negative camber and maximum positive caster. This will be achieved when the cam bolt
shanks are as far outboard as possible. Then take readings and equalize both sides. This will require you to set
the side with the greatest negative camber to equal the least and the greatest positive caster to equal the least by
rotating the bolts to move the shanks slightly inboard.

The front bolt controls camber and the rear controls caster, but there is some cross talk, so you have to do the
process iteratively. Shoot for camber of about -1 degree, if possible, and as much caster as you can get, which will
probably be in the range of 10-11 degrees.

The car must be on a level surface to do this, and most home garages suffice. You can use the camber gage to
check floor level. The control arm cam bolts should be tightened with the car at normal ride height so as not to
preload the bushings in torsion. It's tough to get a 150 lb-ft torque wrench under the car to tighten them with the
car on the ground, so I tighten them as much as possible with whatever wrench will fit, then put the car up on
jackstands to do the final torquing."


In a follow-up query I responded that you can buy a decent inclinometer from any good hardware or Home Depot type store for about $25 dollars.

Duke

P.S. The caster measurement is an approximation based on small angle geometric theory, however, the really important issue is to get as much positive caster as possible and have it equal on both sides. The more positive caster in the suspension the more "negative camber gain" you have on the outside front wheel in a turn. Negative camber gain helps offset body roll, which will keep the tire closer to vertical relative to the ground. This effect improves steering response and reduces understeer. More positive caster also tends to improve straight line tracking and on-center steering feel. Whether the true measurement is, for example, 10 or 10.5 degrees is not important - get as much as you can and equal on both side.

[Mel Weaver]

Thank you for replies! I look at all the "viewed" and wonder why no thoughts/ comments? I guess I do the same-if I can't help I'm out.
Thanks for the replies!!!!!!!!!!
(you know who you are)
-Mel

[csnow]

"Car was very "light" feeling at speeds over 60mph..."

Once alignment checks out ok:

Adjusting the steering box can often improve on-center feel dramatically. Check to see if there is excess play in the steering 'upstream' of the steering linkage. I have yet to meet a 124/201 (admittedly limited sample size) that did not benefit from some adjustment to reign in play. This condition can even 'feel' like a pull to the right on crowned roads.

[Mel Weaver]

124/201 ???
Sorry!
Car MUCH better after alignment!
Thanks for all the support!
Still curious about 124/201 though.
-Mel