Trying to fit an aluminium W126 / 107 trailing arm to a W123 - a question of compatib - Page 2 - PeachParts Mercedes-Benz Forum

Stretch · #1 12-10-2011, 04:35 AM

Quote:

Originally Posted by andydiesel

I'm planning on fiting the alloy arms to my 350sdl - have both steel and alloy arms in my workshop.
My guess is that the anti squat suspension is heavier than the standard one - despite the alloy arms.
Keep in mind any used parts will be at least 20 years old and will likely need rebuild. There are 5 bearings per side. A bearing supplier has quoted me $560 (CAD) for two radial bearings...you may want to change the linkage bushings - likely MB exclusive parts. There are some throwaway parts in the hub assembly...Emerg. brake cables appear different, ditto for the calipers which are mounted forward of the axle...

Tip for buying used: stay away if the steel sleeves sealing the joint connecting the arm to the hub yoke have rusted thru....The alloy will likely be pitted...also check for corrosion at the shock absorber mounting studs.
The brake shield and the emergency brake mounting base may be corroded beyond repair...

Thanks for the info - you must however be fitting second generation W126 trailing arms - aren't you?

I was under the impression that the second generator rear end on a W126 was more akin to the W124 than the W123 - or have I got that wrong?

Even so if you have the time I'd appreciate a photograph or two of your trailing arms and what you are doing.

Have you checked out the prices for the radial bearings at the dealer yet? $560 sounds like a lot for bearings - but hey dealer prices can be a bit strange too!

kerry · #2 06-05-2012, 02:49 PM

Well those rear trailing arms, at least on the 126, seem highly subject to corrosion. Avoiding that problem may be worth it.

Stretch · #3 06-06-2012, 03:15 AM

Quote:

Originally Posted by kerry

Well those rear trailing arms, at least on the 126, seem highly subject to corrosion. Avoiding that problem may be worth it.

That's the only benefit I can see with them.

Now if I go ahead with my OM648 conversion then I'd probably have the torque needed for the anti-dive otherwise with only a N/A OM617...

t walgamuth · #4 06-06-2012, 06:06 AM

The rear calipers on the aluminum setup are floating caliper, similar to the 124 chassis. It looks to me like the conversion is way too complicated for the value offered. (Sorry)

I was very high on the idea originally but after seeing all the differences it looks impractical to me.

the extra weight would be a deal killer for me too.

Stretch · #5 06-06-2012, 10:39 AM

Quote:

Originally Posted by t walgamuth

The rear calipers on the aluminum setup are floating caliper, similar to the 124 chassis. It looks to me like the conversion is way too complicated for the value offered. (Sorry)

...

I forgot to say about the caliper difference...

I don't consider it to be a problem at all just use the caliper that is designed for the aluminium trailing arm. I haven't checked it out yet but the piston diameters look the same - so I don't expect a difference in braking force.

One of the trailing arms came with a caliper fitted - and if it is OK that could save a bit of cash. It is an ATE by the way... they might all be ATEs for aluminium trailing arms... I don't know I'll have to check with the dealer...

Anyway here are some more pictures.

1) The slightly different although similar looking caliper

2) The anti roll bar connection

3) The shock mounting bits (also no problems there from what I can see)

JamesDean · #6 06-06-2012, 09:15 AM

Quote:

Originally Posted by kerry

Well those rear trailing arms, at least on the 126, seem highly subject to corrosion. Avoiding that problem may be worth it.

TRUTH! Passenger side seems most common. My SD and my buddies old SE.

http://www.peachparts.com/shopforum/diesel-discussion/303427-w126-trailing-arm-rear-lower-control-arm-rebuilt-replacement.html

Stretch · #7 06-06-2012, 08:57 AM

I think I'm going to get some prices for the bits that I would need to make these trailing arms totally new and post up that information before I make a final decision. At least that sort of information might be of use to others...

It doesn't look like I'll be going ahead with it at the moment though.

vstech · #8 06-06-2012, 01:06 PM

bump

charmalu · #9 06-06-2012, 01:30 PM

Ok this Kilo gram stuff means absolutly nothing to me, sooooooooo.........
Since Google is our friend

16KG = 35.27lbs

21KG = 46.30lbs

11.03lbs difference.

Charlie

Stretch · #10 06-06-2012, 01:54 PM

I'm sorry Charlie - I'll try and remember to convert any future measurements into old money as well!

So what do you think of the whole idea then? Would you consider doing it? (for the right price of course)

greazzer · #11 06-06-2012, 02:26 PM

Army,

With this upgrade, can you use the bigger calipers and rotors ? Seems like a nice trade off. I would swap 11 pounds for the bigger and better brakes. I would rather lose 11 pounds off my gut. My .02. So, does this whole sha-bang just bolt in ?

Stretch · #12 06-06-2012, 03:27 PM

Quote:

Originally Posted by greazzer

Army,

With this upgrade, can you use the bigger calipers and rotors ? Seems like a nice trade off. I would swap 11 pounds for the bigger and better brakes. I would rather lose 11 pounds off my gut. My .02. So, does this whole sha-bang just bolt in ?

I don't think the brakes are any different operational wise.

I have to check them out still but the caliper that was left on one of the aluminium trailing arms that I bought looks like it has the same sized brake piston in there as the calipers that are fitted on the steel trailing arms. It looks like only the casting is different so that it fits into the slot on the aluminium trailing arm whereas the calipers on the steel trailing arms just bolt on (as I'm sure you know).

I guess this "upgrade" on a W126 would be very straightforward as you'd just remove and replace. The only problem that might occur would be fixing the thicker anti-roll bar to the chassis for the anti-dive mechanism. But that might not be a problem.

As for doing this to a W123 I know that that anti-roll bar needs to be narrower. The W126 is a wider car. The rest of the stuff seems to me to just be a bolt on job though - I might be able to use a W123 coupe rear anti-roll bar or shorten a W126 one for the anti-dive attachments... I haven't gotten that far yet. (And like I've said I'm not sure if I'll go that far!)

The anti-dive mechanism should in principle be a handling advantage when fitted to a vehicle with a powerful engine - but when fitted to a N/A OM617 I guessing it isn't going to have much of an effect...

...oh yes there's a difference of 5kg / 11lbs per side.

charmalu · #13 06-06-2012, 03:45 PM

That extra 11lbs will give the rear tires that extra downward force to help eliminate Burn Outs.

You know with the Turbo added, helps the 617.952 unleash all that awsome power.

Charlie

Stretch · #14 06-06-2012, 03:49 PM

Quote:

Originally Posted by charmalu

That extra 11lbs will give the rear tires that extra downward force to help eliminate Burn Outs.

...

Right that's it I'm not doing it then!

Stretch · #15 06-07-2012, 07:51 AM

I'm quite lucky having both the W123 ATE and W126 ATE brake calipers to compare. If one set had been of another make it might not be so clear.

I can confirm that

1) the brake pads are the same
2) the discs are the same
3) the brake pistons in the calipers are the same
4) the caliper mounting bolt diameters are the same but the bolts are of a different length
5) the distance between the centres of the mounting bolts are the same
6) only the thickness of the mounting side on the W123 caliper is thicker - the casting is slightly different in this area - that's it.

Here are the pictures