W126 aluminum trailing arm swap
 

Well, I was at PNP today and saw a 500SEL with
100K less miles than my SD, so I grabbed the
aluminum trailing arms w/calipers, also the sway bar and springs.
Noticed right off that the sway bar is different.
Calipers are on the opposite side of the hub from the SD, too.


My trailing arms are out now so I figure I'm halfway there.

Everyone talks about those aluminum arms so I nabbed 'em.
Are they plug N play--except for that sway bar.
Also, are the springs & calipers specific to those Alum arms?

Opinions from anyone whose done the swap
would be greatly appreciated.

Thanks,
Jeff

There is a fellow here who has studied it in detail. I believe maybe Stretch. I believe the mounts for the sway bar are larger with the aluminum arms.

The parts from the 500 can be directly exchanged. All of them! The sway bar is part of the anti-squat geometry, and must be used with the rest of the parts.
The caliper hydraulic connections may be in a different place on the caliper, but are otherwise the same.
Springs can be directly exchanged physically, but may be of a different rate.

Does anyone know if this would work in the W116? I know much of the suspension is the same between the W116 and W126 (control arms are identical), but I don't know how much is the same.

Stretch was trying to install them on a W123 w/o good results.

http://www.peachparts.com/shopforum/diesel-discussion/289638-trying-fit-aluminium-w126-107-trailing-arm-w123-question-compatib.html

This thread is about installing them on a w126

http://www.peachparts.com/shopforum/tech-help/295454-w126-rear-control-arms-interchangeable.html

Iam wondering if you also need the Sub frame that goes with the Aluminum arms?

Charlie

Yes, the hardware that attaches the sway bar to the subframe
is different on the two. Larger, with larger bolts and further apart on the 500.

Frank, so just bolt up the new sway bar using the old hardware?
That would be great.
Seemed like stretch was going to have to weld his two sway bars together.
Maybe because it was a 123?

Jeff

I believe the calipers are different on the aluminum arms vs the steel ones. They mount differently and are full floating instead of fixed calipers.

The new bar can be installed in the existing mounts, providing that the bar fits snugly in the rubber bushings. The larger attaching parts in the donor car reflect the additional loads that are applied at that point. The bar in your existing configuration is loaded only in torsion. In the anti-squat geometry the bar is additionally loaded fore and aft; it is a suspension link. While you can bolt it all together, you may wish to consider some reinforcement in the area of the bar mounts, as the factory did.

You might have the same trouble (well it is hardly trouble if you can weld or get someone else to weld) as I have with the conversion to the W123 chassis - the W126 anti-roll bar is too wide for the W123 chassis. The W116 chassis might be of a a different dimension to the W126 - but other than that the swap should be quite straightforward.

I guess the W116 might also have axle related problems as I believe the axle cans on the W116 are larger than the W123 / 6 versions. Check with someone who has been around these beasts for longer than me!

The downside to this conversion as far as a normally aspirated 300D / 240D is that the aluminium trailing arms are heavier than the steel. They are also more complicated and the last time I looked at the prices for the additional bearings and rubber connecting parts I took a deep breath...

...the benefits with a limited slip differential and a powerful engine however would be "well lush"

Heavier? What a letdown!

Yes, I am wondering if the benefits are worth it.
There's a reason they only put them on the bigger engines.

As far as I can tell I would be the first one to do this swap
and am beginning to wonder if this is worth it.

I still need to figure out the bracket mod.

Ok everyone, talk me into it or out of it............

Jeff

Anti-squat. It's the geometry change that is significant, not the material.

I had them on my 84 500 SEC and that was a very sweet handling car. It drove small.

Need to figure out the hardware change.
For those who haven't seen it here are some photos.
The bolts & bracket for the anti-squat bar are substantially stronger.

The anti-squat bar will fit into the existing rubber mount.
Maybe just get a longer bolt and stack two of the smaller brackets together?

If you have the will power take a picture of the underside of your W126 chassis so we can see if another captive nut can be added to the "chassis rail" (it isn't really a rail but you know what I mean) so you can just fit the whole anti-squat hardware

http://www.peachparts.com/shopforum/...p-hardware.jpg

To help me with my project I'm interested in learning the difference in length of the arms of the anti-roll bars (if any) =>

http://www.peachparts.com/shopforum/...p-bar-ends.jpg

But only if you have the time

The size of the bolt difference suggests about four times as much stress will be placed on them.

Well the unsprung weight of the wheels (including the trailing arms) is quite a bit greater...

...so different captive nuts need to be fitted to the chassis.

I will take some more pictures and take some
measurements when I get home from work tonight.

Jeff

go get the subframe... I'm warning you...

I think he'll be all right with that - to the best of my recollection of floating about on the Russian EPC before it all went java script enabled (!) the subframe is the same with or with out anti-dive...

...perhaps a quick butchers on the real EPC can confirm this (I'd do it myself but I don't 'ave it gov)

Stretch,
The original swaybar is apx 11" from the center of the mount to
the bolt hole. I am coming off the bar at a right angle to measure that.
The anti-squat bar is apx 10 1/4"- 10 1/5" measuring the same way.
Attached is a photo of the mount area.

So, is the subframe for the 500SEL the same as my SD?
I take your warnings seriously, John--what would be the problem if I keep mine?

Jeff

forgot the photo.......

Mr. Cogburn (Rooster, that is):

In the supplied pic the bar bushing has been reinstalled; when it was removed did you notice another plugged hole? The visible plugged hole and the hidden one should be spaced correctly, and should be of the correct threads for the new bar bracket!!

Mr. Reiner,
How right you are!!
Those nuts are a perfect fit!
I thought that rubber plug was a drain hole.
I was wondering how to determine where to place the bracket.
Mercedes foresight & planning (and Frank) to the rescue.
Maybe the anti-squat bar was an option?

Thanks again,
Jeff:D

Hmm OK 3/4" difference - thanks.

But it also sounds like the mounting points are in a different position.


As for the subframe - this is a EPC related problem - how many part numbers are there for the damn things?! (I think I remember there was only one number)