Note! Work in progress!
Engine suspension (22/24)
There is nothing complicated about the engine suspension either. But it can be noted that today’s reproductions of Mercedes-Benz’ classic car’s engine suspension seem to be of far lower quality compared to the original ones. Even those bought from Mercedes-Benz. The suspensions fail much earlier. For the Pontons there is a member on the International Ponton Owner Group Forum (see Links) who even has produced “hockey pucks” of harder rubber to install under the left/right engine suspensions so that they don’t “collapse”. Personally, I have experience with this when it comes to the rear engine mount on my three-point suspension (see below). But more about that in a separate blog post.
The 219’s engine suspension, with the later [four-point suspension] mounts crossed out. 220a and some 180/190/190SL models used it as well
Front engine support
The 6-cylinder Pontons have an odd, front motor support (fig #40-52 in the drawing above). What its exact purpose is I haven’t been able to find out. Some say it’s there to prevent the engine from “falling out” if the car flips over. Most say it doesn’t make sense and many drive without it, without any issues. In my opinion, it just makes the engine suspension unnecessarily rigid, plus it's messy to adjust and repair. For different testing purposes I’ve temporarily removed it myself, without any issues, a couple of times. I am however using it since “it’s supposed to be there”…
Front engine support used on the 6-cylinder Pontons
Rear engine suspension
As said in the Restoration article about the engine suspension I somehow lost the original rear engine suspension during the restoration. I ordered a new one, together with its screening plate and an article not in the spare parts list's drawing, a "support plate". The latter came with its two screws. I had no idea what it was and my supplier neither but said it should be ok for my car. I was inclined to believe them but it took me sometime to verify this. Thanks to the VdH forum (see Links) I learnt what it was. See more about it below!
Some of the early 4-cylinder Pontons, incl 190SL, as well as early 219 and 220a (maybe all 220a?!) had a three-point engine suspension instead of the four-point suspension (see drawing above and pictures in the gallery below). This means that instead of two “normal” mounts in the rear, they had only one, fitted on the rear of the gearbox. Later 4-cylinder Pontons incl late 190SL as well as late 219 and all 220S/SE had a four-point suspension.
The 4-cylinder Pontons with the three-point engine suspensions use spare parts number 120 240 04 18 for the rear one. 219 and 220a with the three-point engine suspension use spare parts number 180 240 05 18 for the rear one. An educated guess is that the rubber in the 6-cylinder version is harder. If the corresponding part numbers on newly manufactured suspensions differ in hardness, one might wonder...
The suspension consists of two fairly strong metal plates - one attached to the rear cover of the gearbox and one in two lugs protruding from the chassis - molded together with a thick, resilient rubber. To protect the rubber from oil and road salt, the front of the bearing is shielded by a thin, separate plate.
For the 6-cylinder 220a and 219, a steel stop-block is screwed into the rear and lower metal plate, i.e. the one attached to the chassis. This will prevent the engine/gearbox from sinking so far to the rear edge that the function of the gear levers is affected in the event of a collapse of the rubber. Under the stop block is a 2mm thick washer, or shims, with the form and width of the stop-block.
Tilting the engine axially
An interesting thing is how the rear engine suspension is attached to the chassis. As you can see in the first drawing in the gallery above, the suspension is mounted under the lug on the chassis. And depending on Ponton model there should be washer in between, or not. And if there should be a washer, its thickness also depends on Ponton model. This thus affects the axial tilt of the engine.
I suppose the reason for this design solution is to get the correct angle of the shaft coming out of the gearbox towards the first part of the propeller shaft. But I do wonder how much these few millimeters matter. The axial tilt of the engine will be more affected if the engine suspension, or the rubber between the front axle support (also known as Vorderachsträger or Fahrschemel) and the chassis, starts aging and/or wearing out. Not to mention the importance of tight tolerances in the manufacturing of these suspension parts, or that you would need to replace all the parts in the engine suspension even if only one is in bad shape.
“Export Sonderwunsch” Support plate
Another interesting thing is that for the 4-cylinder Pontons you could order the 6-cylinder version as “Export Sonderwunsch”, or “Export special request”. For both 4- and 6-cylinders you could order - also as “Export Sonderwunsch” - a “Support plate for rubber bearing” 180 240 00 43. As I’ve understood it, these 6-cylinder parts were not available as “Export Sonderwunsch” for the 190SL. Please correct me if I’m wrong.
I, or for that matter any of the Ponton people I've talked to, hadn’t heard of this “Support plate”, let alone seen it in real life, before. Exactly what it would add is also not clear, as it attaches to the rear/lower metal plate as well as to the same lugs in the body that this plate uses. And both the mount’s metal plate and the lugs should be strong enough. If you want to use it it was recommended on the VdH forum to mount it together with two pieces of rubber, MB spare parts number 116 987 06 41! If you have any further information about this support plate, or the assembly together with the two rubber pieces, please let me know!
Self aligning the complete drivetrain
After an initial installation of the complete drivetrain assembly, from the front engine suspension to the propeller shaft support bearing housing, I would recommended to leave the fasteners not fully tightened. Roll the vehicle forward and backward several times to permit the components to settle and self-align. When correct alignment has been obtained, tighten all fasteners to the specified torque. Then install and tighten the front engine support.
