Rear suspension swap

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ibast
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Model you own: w108
Location: Sydney

Rear suspension swap

Post by ibast » Thu 28 Jul, 2016 9:31 am

Hey guys,

My original plan for this car was to get it registered and then do a driving resto, with minor mods. Maybe do a v8 swap down the track.

Since I've started, I've found more problems than I thought (isn't it always the way?).

The rust at the leading edge of the drivers rocker panel extends down into the chassis, to the point I think it may not pass a blue slip. Also the engine is smokey, not only on start up, but after extended load. This indicates that not only have the valve seals gone, but the valve guides are cactus too.

And I'm betting I haven't found all the problems.

So now I'm leaning towards doing the engine swap and cutting all the rust and respraying before I do the rego.

So, finally, to the question. Since I will likely have a whole w116, does anyone know anything about a rear suspension swap?

And since I haven't driven my car much, how is the original swing arm suspension? I know a lot of people will tell me it's good, but does it have the same problems at the limit that this type of suspension is comonly renown for?

It's probably more hassle than I'm willing to get into at the moment, but since I'll have the w116, I didn't want to give it up if I could just pull the suspension and axle. Of course that in itself presents a problem, because I haven't got the space to leave a imobile hulk around. After I pull the parts I want, it will be gone.

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Bartman4800
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Re: Rear suspension swap

Post by Bartman4800 » Thu 28 Jul, 2016 10:19 am

With the smokey engine, it might just be that the valve guide seals have gone hard.

I put the nulon stuff to soften oil seals in my finnie engine and the smoking stopped very soon.
To determine the state of your engine (what is it? A 250/280 S or SE?) you can perform a compression test and a leakdown test.

A rear end of a W116 will not fit under a W108. It is completely different. W108 has swingarms, W116 is fully independent.
Everything can be mated together, and some people have installed a W124 rear end. So have a look at that.

Good luck

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

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pastelgrey300D
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Re: Rear suspension swap

Post by pastelgrey300D » Thu 28 Jul, 2016 10:33 am

As Bart said it would be a massive undertaking, but anything is possible with a bit of fabrication - I think the W124 rear end is because the W116 had a much wider track than the W108.

The W108 swing arm rear end is not as bad as other swing arm cars (corvair, beetle etc), I think this is because MB fitted a decent rear sway bar. Steve (SF099) has done lots of classic rallying and track work in his Finnie which has the same rear end. If you do ditch the W108 diff, post it up on here because a W108 diff into a Finnie is a popular upgrade because the 108 has rear discs.
David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

ibast
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Re: Rear suspension swap

Post by ibast » Thu 28 Jul, 2016 2:24 pm

Thanks guys, next thing I was going to do is check the wheel track, but from photos on the interweb it looks like the whole sub-chasis would sit up there.

Fab some mounts for the front of it, provided they didn't sit too high. Simlar with the sway bar mounts.

Then it would be a question of whether the sub chasis didn't interfere with the body.

The biggist thing would be the top mounts for the springs and shocks. It would only be pure luck if they lined up. so this is what I suspected would kill it.

Anyway, if the track is too wide then I won't waste any more time on it.

As for the smokey engine, I was kind of hoping the same. I put Nulon in at the oil change, but the smoke it blew after the sustained throttle in the driveway really put me off. It hasn't however has a long enough run to work it into all the seals. It is a 250SE BTW.

I'm still on the fence at the moment, but leaning the way of the m117 swap. I was going to do it in the long run anyway.

I have another obscureish question.

My car has 4 speed with the round type filter. It has numbers on the tag, but they don't seem to align with anything I've found online. It's got the early type seprate hydraulic clutch, rather than the later stall convert.

Does anyone know if this will fit or handle the torque of the M117?

I'd like to keep the column shift and the 4 speed would be pretty handy.

Is the 4 speed fitted to m117s different?

ibast
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Re: Rear suspension swap

Post by ibast » Sun 31 Jul, 2016 5:58 pm

OK. so as an alternative question, what crown wheels and pinions fit in my diff housing? The interweb seems to agree that the 3.5 and 4.5 diffs don't fit. And that Finnie diffs do.

What about W114s? It seems that 123s fit in W114s and they are about the right ratio and not too expensive.

Checked today and mine has a 3.92 so that's not going to work with a v8.

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Bartman4800
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Re: Rear suspension swap

Post by Bartman4800 » Mon 01 Aug, 2016 10:30 am

I don't think that any of the later model pinion and crown wheel will fit.

Finnies (W111) are the predecessors of your car. A w108 is basically a more boxy version of the finny. Both cars have the same suspension setup.
Finnies never came out of the factory with anything other than a 4 or a 6 inline. W108 came out with bigger engines, including V8's.
Finnies will always be geared lower than a W108.

All later cars have independent rear suspension, instead of the swing axle. Maybe someone here can tell me wrong but I don't think that anything rear axle wise after the W109/9 will be backwards compatible.

Find yourself a W109 6.3 rear axle; that will be able to take the HP you are intending to unleash on it.


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

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pastelgrey300D
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Re: Rear suspension swap

Post by pastelgrey300D » Mon 01 Aug, 2016 11:38 am

Have a read through this thread on benzworld - some talk in there about 124 rear ends etc.

http://www.benzworld.org/forums/vintage ... 08-10.html

I'm pretty sure that the W116s with the M117 V8s were only 3 speed auto. But it shouldn't be too hard to connect up the linkages to retain the column shift - you can buy the end pieces for the linkages and then just custom make your own linkage rods and use a die to cut the thread on them.
David
1967 W111 230S - Horizonblau
1965 W110 190c - Mittelrot
1967 W110 200D - Weiss (work in progress)
+ other classics

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sf0999
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Re: Rear suspension swap

Post by sf0999 » Sun 07 Aug, 2016 6:43 pm

Hi All, As Dave mentioned I have a fairly standard Finnie and have done some track days etc. The suspension feels very stable and from what others have commented when following me, the car looks ungainly, but the wheels seems to remain vertical where needed. Surprising how well it works on standard road tyres. What it would be like with big HP, I'm not sure.

I would be interested in the disc brake rear end from a 108 if it was to become available...

Steve
W111 1961 220S Classic Rally Car "Eugen"
W126 1988 300SEL "Frankie"

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Mercmad
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Re: Rear suspension swap

Post by Mercmad » Mon 08 Aug, 2016 12:00 pm

you can fit a w116 diff under a w108 but you need to weld in a crossmember to support the rear mount and wo front mounts.i have seen it done with a big 560 diff. not hard but time consuming .

ibast
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Re: Rear suspension swap

Post by ibast » Tue 09 Aug, 2016 12:44 pm

Thanks Mercmad. I suspected as much. When I checked widths there was only an inch in total difference.

The w116 I was looking at didn't eventuate, however, but I now have w126. Although I haven't looked under it yet.

ibast
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Re: Rear suspension swap

Post by ibast » Sat 20 Aug, 2016 2:36 pm

Looking at the w126. It looks like the rear mount would be a snack. You'd just have to fabricate a top hat section or use a RHS.

The front mounts look like it would be a different story. They extend forward beyond the w108 front mount cross member. So it could be done, but you'd have cut channels in the cross member and fabricate a new cross member. You'd also have to fabric new pockets for the front mounts.

Possible, but you'd need a rotisserie. More work than I'm willing to do at the moment.

Pity. For some reason the w126 has a 3.27 diff in it. I still might drop the diff out itself.

Barbady
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Re: Rear suspension swap

Post by Barbady » Sun 04 Aug, 2019 7:44 am

Great

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drew56cus
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Re: Rear suspension swap

Post by drew56cus » Sun 04 Aug, 2019 9:17 pm

Mercmad (in Brisbane) has since put a 126 rear end into a finny (same set up at 108), though we have not had the chance to take it for a fang yet to see if it was worth all the effort. The front mounting points lined up with where teh trailing arms bolted to. He bought a new crossmember and welded that in, and did some slight shape adjustment to the finny chassis rails for the rear sway bar to mount to. I can't remember what springs he had to run.
20161119_112016.jpg
What is your interest in this Barbady? What are you scheming?!
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Drew
'65 220SE 4.5 Frankenbenz finnie :)
'65 220SE/C (#1 project - Tenorite grey)
'64 300SE/C (#2 project)
'66 250SE/C (#3 project)

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Mercmad
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Re: Rear suspension swap

Post by Mercmad » Sat 10 Aug, 2019 8:15 pm

Hi, yes i did indeed do this for a bloke who gave me a finny and a W126 560SEl (RuF 10-1 compression !!!!) and asked me to combine the two. If I were to do it again I would raise the floor under the seat so the diff can sit higher into the car .
An old mate in the Uk had done this before me with his W108. But he also used the self leveling struts .
I've read about 3 or 4 others including a coupe in the Uk with the same deal.
To make it fit,there is a crossmember welded into place from side to side which the rear diff support is bolted to .
A spacer is needed to angle the diff nose up so the shaft is level.
The two front mounts are made from 5 mm plate (120 x 250 ) to which threaded nuts are welded to . The two large bolts passing through the front mounts hold these in place.These were welded inboard of the rear jack points.
Behind the diff I had to make brackets for the sway bar which on the 5560 Diff acts as a top link. These brackets are also welded in place.
The spring mounts lined up but the 560 Springs are for the hydro struts so a too light. They are also 150 mm too short. I got around this by making a tube with a ring that the spring sits on . this allows the car to sit level .
If you want the car to assume a lowered look ,the diff will hit the ground. Not good.
But if you are into posing,air bags instead of springs will work well.
The front discs were uprated with the 560 rotors and calipers but these are cactus and will need replacing. The other matter is wheels, the minimum is 15" diameter.

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Re: Rear suspension swap

Post by CraigB » Sat 10 Aug, 2019 8:26 pm

without hijacking the thread too much..... did the rotors bolt straight up to the 108 hubs? What about mounting calipers - any adaption?
Craig Baulderstone
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Mercmad
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Re: Rear suspension swap

Post by Mercmad » Tue 13 Aug, 2019 7:52 pm

The calipers will bolt directly to the second series W111-113 ,etc stub axles. (there's two types small center line calipers ,3 piston type and wide center type with 2 pistons) but to fit the rotors i had to make new hubs .

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