Swing Axle Swap With Newer Type

[Squiggle Dog]

Has anyone replaced their swing axle with a newer type? I want to replace the 4.09 rear axle on my 1967 W111 fintail with one from a 1970s-1980s W116, W123, or W126 for 3.07 or 2.88 gears. I'm wondering if it can be done without cutting and welding.

[tompaah7503]

Originally Posted by Squiggle Dog

Has anyone replaced their swing axle with a newer type? I want to replace the 4.09 rear axle on my 1967 W111 fintail with one from a 1970s-1980s W116, W123, or W126 for 3.07 or 2.88 gears. I'm wondering if it can be done without cutting and welding.

I have never ever heard of anyone doing that, but given enough time and a good welder anything is possible If you manage to pull that off, post a tutorial, and get rich selling conversion kits.. Don't forget that the W110/111/108-axles have the gear casing slightly offset from centre, and the later models does not, so that might give you some issues with driveshaft clearance.
Btw, is there any particular reason you'd want to do that? The swing axle performs quite well for it's age and if you want the disc brakes a 108-axle will do fine.
I'd think a 108-3.96, 14 inch wheels and a fifth gear would be the most cost-efficient and easy solution for you.

[Arthur Dalton]

Just get the rear from a 108 280SE/SEL-4.5...it is 3:27 and is swing , so it fits.

[bgkast]

3.27/1 would be just about ideal for a manual 617 turbo powered rig.

[Arthur Dalton]

The 113 owners all do it with great results.
I remember doing these conversion/swaps years ago and getting all kinds of flack for doing them..
But now it has become The Rave ... and the guys raving are the same ones that dumped on the idea back then ...go fiqure.

They have an exterior oil cooler tube that has to be blocked off..and that is how you can recognize them just peefing under the car.

Ratios are stamped into the lower/left machined flat , just in front of where the left/ outer axle tube bolts to the casing. [ will be the last 3 #s , and they will read with a coma, not a : i.e. 3,27]

[JMela]

Video on the 4.5/3.27 axle swap. Video is from a w113 GTG, but there's a lot of good information here that should be applicable to the 108/111 crowd as well:

http://video.google.com/videoplay?docid=6365474313884505435

[Tomguy]

Originally Posted by Arthur Dalton

The 113 owners all do it with great results.
I remember doing these conversion/swaps years ago and getting all kinds of flack for doing them..
But now it has become The Rave ... and the guys raving are the same ones that dumped on the idea back then ...go figure.

All it takes is gas to cost more, then the idea of getting a few dozen more miles on a tank is enough to sway those people

If you were going to attempt to put a 116 or 126 or something in a 111, you're braver than I. The most I would do would be to add a swaybar or something to stiffen that axle up a bit. Which would involve some welding and cutting and so forth...

[Arthur Dalton]

.

For sure ..those rears had a completely different, control arm, open axle suspenson. ..along with ball joints in the frone.
Swing axles hang from the trunk and have trailing arms with a pivot pin and compensating coil.
Prolly be as easy to put a half-Track in there as it would be to convert to the open axle dif....

[Squiggle Dog]

Thanks for the input. I was wondering about the newer axles because it seems the lowest gearing the swing axles came with was a 3.27, which is passable, but I think something much lower like a 3.07 or 2.88 would be better. I might look into seeing if I could customize a swing axle by having a gear set made, or find some gears that were close enough that they would work and fit in the housing to give the swing axle a 2.88 gear ratio. But using a 3.27 W108 swing axle with disc brakes would probably be fine.

I just wish that the OM617 5 cylinder turbo diesel engine was around back when they made this body style, and that it was offered in the fintails with a manual transmission.

[Arthur Dalton]

Quite a difference from 4:09 to 3:27..specially when you are under-powered to begin with.

[Squiggle Dog]

The car is not yet in drivable condition, but I hear that with the stock 4.09 axle these cars only have a top speed of 50 mph when they have the OM617 transplanted into them. With the proper gearing, cars with this engine are quick and will easily do over 100 mph. But, yes, going from 4.09 to 3.27 will probably improve the top speed substantially (I want it to do at least 70 mph while having low enough RPMs to not be harming the engine and get the best fuel mileage). The car originally had a 6 cylinder gasoline engine, but the engine had holes in the block, and I have been wanting a turbo diesel fintail for a while.

[mercmad6.3]

I haven't done this myself ( only fitted V8 diffs to Finnys and seen others do it) but the way to fit the later 4 link under a W111 is easy. What must be remembered is that the W111 pan is very flimsy at the rear ,it's a crumple zone.

Start by lifting your car and removing the fuel tank and old diff. Removing diff is time consuming to say the least. You need to get the car on stands and stable about 3 feet off the floor.
start by disconnecting the front arms ( one large nut and three small bolts ) with a jack under the arm to take the spring pressure. Lower the jack once you have arms disconnected. Undo the hand brake cables by loosening the lever on under the tunnel so the cables are slack then undo the nut on each cable housing where it is connected to the floor panel.
Then just wriggle the cables free from the lever link.
On the dif head you will see a cross movement rod which prevents sideways movement. In the diff end is a large bolt,undo that then the smaller bolt next to it. The rod can then be pushed clear of the diff head.
get into the trunk and undo the shock absorber nuts. The axles will drop down each side so be careful when then they release.
In the center of the basck of the trunk is a plastic cover,remove this and underneath you find a rubber mount with Four bolts and a large 22mm bolt in the center ,loosen the large bolt but don't undo it yet.

Under the car now.
Undo the shock bolts on each side and remove the shock absorbers. You can now see the brake hoses ,cut them off . cut only the rubbers .
Now place a trolly jack under the diff to take the load. it's an arkward thing so make sure it balanced ok.
Now undo the large bolt in the trunk so that it's about 6 threads still engaged.Lower the diff by releasing the jack. If it won't drop,belt the bolt with a heavy hammer to loosen it in the rubber mount.
once it moves down you can remove the bolt and drop the diff completely.

Now... under the car you have to cut off the center rod bracket,the large thing hanging down in the center of the floor.

Carefully remove the brake lines and the brass mounts. you will need those later.

To replace the diff ,you will need a complete diff assembly from a W114,114,107,116 ,123 or 126 . plenty of variety to choose from and all are suitable. The ones to avoid are 450SEL 6.9's because the ratio is way too high for your car and earlier type without the antilift links. it doesn't matter if they are from a vehicle with self leveling because you can't use the shocks. try and get one with the torsion bar. I note a lot of US market cars don't have this.
you will also need the brake booster and master cylinder from your donor vehicle.
with your diff assembly on the floor,you can see where you will need to fabricate the front mount for the diff carrier and the center mount for the diff head.

Under your car you need to weld in a crossmember to run from side to side in the approximate area of the shock absorber mounts. This because the floor pan in a W111 doesn't have any strength in this area and you will mounting the diff head support there.
Once you have this in place it's then a matter of raising the diff and determining the spring mount points. You need heavier springs because of the leverage imposed by the later trailing arms is greater than the W111 arms and W111 arms being 'softer' cause the car to squat under aceleration.

With the car supported by the diff you will now need to connect the brskes using the origial rear feed line (replace it if rusty etc ) and the new hoses you bought .the brass mounts will have to moved out wards to ensure the hoses reach and wil not be stretched.
The later booster and master cylinder must be used because of the brake swap. In the front of the car is a bias valve in the brake line feeding to the rear,remove this and fit a W108 fitting in the line that asllows the two line ends to be joined once the bias valve is removed. the older style W111 master cylinder won't work rear discs.
If you have front drums or the small W111 discs you need to swap in W108 or 109 spindles and discs as a complete assembly. The W11 discs have a different size disc and smaller pitch circle on the caliper mount . This small disc is incompatible with rear disc brakes . W112's have an entirely different 4 wheel disc brake set up and should not be confused as to compatibilty.
The hand brake is a problem and new cables have to be either made or W126 SEL cables sourced so they reach the link under the floor panel.
The drive shaft is your next project as the later diffs have a flex disc mount the diff head. your only option is to cut and shut a later shaft coupling to the W111 shaft.
once on the road the car will be transformed ,with an unbelievable ride and modern handling.

[bgkast]

Originally Posted by Squiggle Dog

Thanks for the input. I was wondering about the newer axles because it seems the lowest gearing the swing axles came with was a 3.27, which is passable, but I think something much lower like a 3.07 or 2.88 would be better.

I currently have a 3.69 rear in my turbo 617/manual transmission car. It is usable, but is a bit too wound up on the freeway for my tastes. I have a 3.46 ready to swap in which should be just about right. IMO a 2.88 would not be drivable with a manual transmission, a 3.07 would be marginal.

[mercmad6.3]

Originally Posted by bgkast

I currently have a 3.69 rear in my turbo 617/manual transmission car. It is usable, but is a bit too wound up on the freeway for my tastes. I have a 3.46 ready to swap in which should be just about right. IMO a 2.88 would not be drivable with a manual transmission, a 3.07 would be marginal.

yes,right there.The high ratio diffs are definitely auto trans only . As a point of interest, the 'USA only' W108 4.5's have 3.23 diff and these were available only in the USA.The 3.27 diff is used on USA 3.5 and others. All other markets have 3,67-1 diff which was the closest available .

[Arthur Dalton]

<< the 'USA only' W108 4.5's have 3.23 diff and these were available only in the USA.>

USA 280se/sel 4/5 are all 3:27 ...