W124 Front Control Arm Bushings
 

Hello,

How can I check if my front control arm bushings are in installed properly? I have read the factory manual and they say that the rears should be installed with flat parts vertical and fronts should be horiztonal.

A mehanic installed them 9 months ago, with parts from Rusty Cullens. These parts have 3 bumps on them on opposite sides. Does this correspond to the flats parts? On all four bushings, the 3 bumps are at top and bottom, which MAY sugest a problem.

In additon -the rears look fine, BUT the top part of the bushing in the front looks compressed such that the rubber is squeezing out at the top (bottom looks okay).

This seems like a problem to me!

Am I correct in thinking the front, front control arm bushings are improperly installed and/or failed? ... which could be the cause of the vibration I've been having.

Thanks,
Brian

Surprised you got no responses.

I can't remember whether the bumps line up with the flats or not. I may have some old bushings kicking around to check.
As you suspected, if they are all facing the same direction, they are not installed correctly.

As you stated, the front bushings should have the flats facing horizontally, and the rear bushings should have their flats facing vertically.

How significant is this distinction in terms of handling?
I'm really not sure, but I would like to hear from Steve!

This orientation would seem to encourage a slight toe-out adjustment as rolling resistance increases.
Of course, it may only be relevant under heavier turning loads, in which case it seems that this would encourage mild understeer, or at least a slightly delayed reaction to steering input.

I'll even float a 3rd theory (why not, I'm on a roll!): The spring exerts more downward force on the front bushing than the rear (due to its position), so this orientation simply 'levels' the control arm.

Either way, I would speculate that this is not the cause of your vibration.

Not sure if the 'squeezing' you mention is an indicator of the condition of that bushing, but I will note that the 'top' of the bushing is under load while stationary, because the spring is pushing it downward.

Steve has posted information about this in another thread of 767Flyery's but in his case the REARs were incorrect and Steve mentioned these are critical.

So, I'm not sure if the fronts would cause the same type of problem/vibration :(


Brian

I am also not sure if tightening the bushings with the wheels hanging in the air and no support under control arms would wear out bushings in no time, yet still appear to be "tight" ...

I know what Steve's comments are in relation to 767Flyer, but I'm cautious to assume they apply directly to my situation.


Brian

I am holding a set of these bushings in my grubby little meathooks right now. On both sets of bushings ("two-bump" and "three-bump") the flat parts line up with the bumps.

Jeff Pierce

Thanks for the comments. I looked at many 300E's at my mechanics shop, all also had the bumps (lugs in factory manual) horiztonal and rears vertical. I was also able to see several bushing kits and the flat spots matched up in all cases.

Next week I'll get new bushings installed and see if it helps.

Thanks
Brian

BTW, what did your mechanic quote you for hours on replacing the bushings. The reason I ask is that my local MB dealer quoted me 4 hours just for the press work. (not including removing the control arms from the car.) Seemed high to me.

Jeff Pierce

The dealer wanted $500 for the job, including alignment. My mechanic ended up charging me more, 8 hrs, because one of the bushings needed to be cut out with a torch.

This info is too late for you, but maybe someone else can benefit from it:
I got brand new control arms with new bushings and ball joints already pressed for my '92 190E -- and it was cheaper than the parts and press-work labor. (even with me removing and re-installing the control arms myself)

Jeff Pierce

tvpierce,

This is what I'm scheduled to do. I ordered the parts from the dealer on Tuesday and am having them installed next Wednesday :)

Brian

I'm not a professional mechanic, but I have rebuilt 3 pairs of control arms this year, once with access to a hydraulic press, and twice without.

IMHO, 4 hours is too much for the press work. 1-2 hours for a pair seems fair, including R&R of all bushings and balljoints.
The bushings are sometimes stuck, but drilling through one of them, and knocking the other one out from behind does not take very long.

$500 for the whole job including alignment is a good deal.

Email the control arms to me, and I'll do it in an hour with my [now perfected] 'vice and big hammer' technique :D

csnow,

Were you able to press in bushings and ball joints with just a vice? If so, do you mind elaborating on your process/technique?

Jeff Pierce