Hi Jamie,

I wanted to thank you for the excellent Zenith resource which I constantly refer to. I have a question, when you rebuilt the rear susp, did you follow this guide which I read once on the mbz.org list? I always wondered how relative it is.

"My two cents on the rubber carrier bushing for the rear axle (of the swing axle variety).

The correct installation of this bushing is paramount to the ride quality of the rear of the car. If you've already done everything and you're still not impressed with the ride of the rear (it's too harsh over bumps and you notice every little undulation in the road), chances are that the alignment between the carrier arm and differential are incorrect.

The chances of this bushing having been replaced over the years (probably a couple of times) are excellent, and the chances of it having been done correctly are slim. Without going into all the technical details, suffice it to say that unless the centerline of the swingarm hinge pin is absolutely parallel to the horizontal line of the vehicle, the axles cannot swing freely through their arc. The further the centerline of the hinge pin is from its correct position, the less capable the suspension is of absorbing road irregularities, and therefore, the worse the ride.

These rubber bushings are a fair amount of work to install correctly, and I'm sure that this accounts for most of the problem. However, there are profesional mechanics out there that don't understand the goal either.

Several years ago I decided to rebuild the rear axle of my 300SEL 3.5. I did everything myself, including installing and aligning the carrier bushing. Once completely back together, I took the car down to the Benz garage to have the side-to-side alignment of the rear axle set (they have the alignment bar and I don't). Well, they decided to do me a favor and realign the pinion angle as well, since it "wasn't pointing in the right direction" (this is controlled by the alignment of the carrier bushing). I had spent a great deal of time and effort to get the carrier arm position exactly right while the rear axle was out of the car and these guys had screwed it up. (In their opinion, the pinion was supposed to point directly at the back of the transmission.)

Well, I made the mechanic ride in the back of the car for a few miles, just to make sure he knew what it felt like. Then I made them pull the rear axle out of the car and realign the carrier arm on the bushing per factory instructions. They then put the rear axle back in the car. (The agreement was that if it improved the ride, they would eat the labor costs, and if it didn't improve the ride, then I would pay the labor costs.)

The same mechanic spent a few more miles on the backseat, and willingly stated that he hadn't been in a 109 with such a good ride in 20 years. They ate the labor costs.

There is more going on in the mechanics of the Benz swing axle design than readily meets the eye. Study it and ponder why it is designed the way that it is. Then FOLLOW the factory proceedure for replacing the carrier bushing.

Watch out for this! This really is one of those jobs where if you're not going to do it right, there is no point in doing it at all.

Chris Johnson"

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1967 230S automatic
Boston, MA