Seeking advise re: the front end before I start taking things apart - PeachParts Mercedes-Benz Forum

RML · #1 07-23-2011, 05:15 PM

My 85 300D has been wandering a bit when I drive on the highway. It started as a slight sensation that I was having to correct the straight path between the white broken lines at highway speeds. Then it became more noticable and constant, so I knew it was not my imagination. I tightened up any play in the steering wheel with the adjustment nut on the steering box, but the problem is still there. Now it has revealed itself further in that when I turn the steering wheel slightly, not enough to change lanes, the car kind of over responds and then comes back. The front end kind of sways.

This car has only 48K miles on it, so I am thinking that it must not be a wear issue but rather a rubber bushing that has deteriorated. I did change a ball joint about a year ago because of a cracked and deteriorated boot. I have not gone any deeper into the front end than that and do not have experience with extensive front end work.

Any thoughts on where I should look first? I am guessing that I do not need a total front end rebuild.

Richard

leathermang · #2 07-23-2011, 05:19 PM

I am worried by your description that you have mis adjusted the steering box.... that is the last thing I would have touched with that mileage...
Guessing is not good on front end work or brakes...
take it to someone who knows how to diagnose it.... then decide if you are able to do the repair yourself safely...
You could put your rear tires on the front... see if that changes the feel... best to rule out easy things first...
PS.... some things deteriorate due to age.....not just mileage....like rubber bushings....

tangofox007 · #3 07-23-2011, 05:39 PM

Has your camber gone negative?

leathermang · #4 07-23-2011, 06:09 PM

I think that takes some special tool to measure... ???
I was looking at it in the FSM the other day.......

RML · #5 07-23-2011, 06:38 PM

I was going to take it to a garage where I know the owner. He used to do the alignments for the local Mercedes / Rolls Royce Dealer in my town when it was open. (It closed last year. The owner was in his 80's and did not want to modernize so MB and Volvo took the franchise away from him.) I figure he knows what he is doing. I have not gotten up there yet and was going to look around at the steering components to see if I could identifiy a bad part before I do. Maybe I should just leave it there and get his advise as a starting point.

leathermang · #6 07-23-2011, 07:57 PM

That is a great deal and I encourage you to do just that...
I wish I had someone I could get that kind of info from..

tangofox007 · #7 07-23-2011, 08:21 PM

Quote:

Originally Posted by leathermang

I think that takes some special tool to measure... ???

In some cases, the upper control arm bushings sag enough for the unaided eye to see the negative camber, either by looking at the vehicle head-on or looking at the inside edges of the front tires.

If the upper control arm bushings are original, it's a safe bet that they are history at 25 years old.

Stretch · #8 07-24-2011, 05:56 AM

The first thing I'd do is look for any wear patterns on the tyres - then I'd look for obvious problems underneath such as cracked rubber / bent stuff / loose stuff (it sounds so technical!) - then I'd check the alignment or get it checked.

leathermang · #9 07-24-2011, 09:03 AM

IF you have the two volume Chassis Manual for these cars... you see that the Normal Wear pattern they picture.... is one which on older American cars looks like a front end with problems..... So one needs to consult that manual to evaluate that as a potential symptom.

Stretch · #10 07-24-2011, 10:51 AM

Quote:

Originally Posted by leathermang

IF you have the two volume Chassis Manual for these cars... you see that the Normal Wear pattern they picture.... is one which on older American cars looks like a front end with problems..... So one needs to consult that manual to evaluate that as a potential symptom.

Now there's another reason to buy paper instead of the CD...

leathermang · #11 07-24-2011, 11:21 AM

Quote:

Originally Posted by Army

Now there's another reason to buy paper instead of the CD...

The understatement of the ( some long period of time )
The difference between going down paths and backing out looking at subjects.... and being able to turn the pages and see what is there is tremendous...AND MB hide a bunch of things about one thing in sections you would not look for them.. and could not search for them due to not knowing what nomenclature they used when writing about it.... reading them has been a real eye opener for me...
I wonder if anyone has more paper manuals than I do... and I have zero CD's ...

Stretch · #12 07-24-2011, 11:29 AM

Quote:

Originally Posted by leathermang

...
I wonder if anyone has more paper manuals than I do... and I have zero CD's ...

I hope that will be "the dealer"! Though it wouldn't surprise me if it wasn't the case...

leathermang · #13 07-24-2011, 11:32 AM

Quote:

Originally Posted by Army

I hope that will be "the dealer"! Though it wouldn't surprise me if it wasn't the case...

LOL , That did not occur to me... yes, hope they do... I meant our members of the forum collections....and the dealers should have TSB's they do not even share with lowly common indy mechanics and owners of the cars....

sixto · #14 07-24-2011, 12:52 PM

The wandering you describe can be attributed to worn rear suspension subframe bushings as well, particularly that bit about taking time to stabilize after changing lanes.

Sixto
87 300D

scottmcphee · #15 07-24-2011, 06:28 PM

Too much toe-out (actually, any toe-out) on the front wheels can cause this wander. It doesn't take much. Quick alignment check will rule this out. You want zero toe / dead straight at the front. Well, maybe slight toe-in if not using a road force bar when doing alignment.