Riddle me this racing aficionados

[jwonder]

Hello,

I was browsing around the Internet yesterday and I came upon this very strange rear end suspension configuration on a plunger frame. I am wondering if this is an "official" racing suspension or just something someone put together. I still don't fully know how it is working from the pictures but I am studying them more!

[schrader7032]

Isn't it just a different type of shock (as in exposed coils) used on a plunger frame? The top and bottom parts of the shock are fixed. The axle comes over and connects to a moveable part of the shock that is connected to the lower coil of the spring. As the axle goes up when hitting a bump, the spring compresses.

[caker]

I'm pretty sure this is homebrewed and/or Russian, and/or cobbled together nonsense? I found the listing it came from and it's kinda a mess.

Some (early?) plunger final drive cover castings did have a cast-in boss to accept a suspension friction damper? ... I don't know too much about it - perhaps a holdover from the prewar R51 racing era, or perhaps BMW had intentions of making the damper part of production but was later abandoned...

Before I post your own pic back here as an example of the boss, you have a picture of one that you sent me a week or two ago

-Chris

[jwonder]

You mean this boss.

[caker]

Ya!

Some pics I took at BMW in Munich:

-Chris

[stwilliams]

The flat round area or "boss" was indeed intended for the application of a hydraulic damper on the right rear of late plunger bikes. So you may see starting around 1953. The damper was never put into production.

You mean this boss.

Screen Shot 2021-02-03 at 9.47.52 PM.png

[stwilliams]

As others pointed out, this is 100% conclusively NOT BMW racing product. Cobbled together and/or fabricated by previous owner. Perhaps was a sidecar at some point given some of the brackets/handles that are on there. Interesting from an ingenuity standpoint, not so much from an originality standpoint.

Hello,

I was browsing around the Internet yesterday and I came upon this very strange rear end suspension configuration on a plunger frame. I am wondering if this is an "official" racing suspension or just something someone put together. I still don't fully know how it is working from the pictures but I am studying them more!

inzerce_zoom_343342.jpg

inzerce_zoom_343347.jpg

inzerce_zoom_343349.jpg

[jwonder]

Ya!

Some pics I took at BMW in Munich:

2A0660EB-6542-4A72-8F2C-EEA2D6AA082D.jpeg

624A5565-E150-4F0A-83C9-FE1E7A54617C.jpeg

360EF437-D459-4643-89BE-D8369EF54764.jpeg

45F7164D-0025-470D-936F-EB970A41DDA6.jpeg

FAF32926-D1BA-4EC7-8D7C-AFD4BF6E476F.jpeg

-Chris

I like that friction damper. I could build one of these fairly easily. Hmmmmm.