I took some pics (btw, all the pics can be clicked on to get larger image) of the plates in an attempt to see those “burrs” on the holes or slots that are implicated in the hump or STA (self torque amplification) event. I think having my sketch diagram of how the plates and spacers are arranged would be useful here:
Here is the stack as it comes out of the VC. Note that the circlip and shims are not on the end of the shaft. Also note that the top plate is not held in the stack by the circlip, but rather is pressed against the endplate when installed.
The reverse side of that top plate, obviously worn.
And the slotted plate below.
Now remember, these two top plates are not spaced apart. The next plate however, is spaced from the slotted plate you see by approx. 0.025″. Mis-focused on this pic, but included it to keep the arrangement clear. See the wear on it even though it is spaced from the plate above?
Here, with the above plate beside, slotted plate turned over.
Here are the adjacent surfaces of another pair, same arrangement as the worn pair above, ie has spacer separating them. Note that they are not worn.
Now lets get a better look at the punched holes.
Closer, I’d say there was a raised rim, very subtle.
And a shot of worn plate holes. I think you can see where the rim/burr whatever you want to call it has been worn.
I only had time to get one close up of the slots in the other plate type, no rim evident on this side at least.
Well, this exercise demonstrated, to me at least, that there are burrs on the punched holes. As to the role of these burrs, I will deal with that in part 3.
#1 by Oscar Karlsson on December 3, 2011 - 4:33 am
Great post! I really enjoy all the images and details in all your vanagon posts.
#2 by IdahoDoug on December 3, 2011 - 10:36 pm
Nice – love the shot of the slotted plate as well. How’d the other side of it look? Based on the diagrams, I expected some “shaped” aspect to this plate to cause it to favor flexing, eh?
#3 by albell on December 4, 2011 - 6:40 am
I’ll take more pics of the slots, ran out of time the other day. Maybe can see some rim/burr/whatever
#4 by Jerome on December 4, 2011 - 7:22 am
Good job Alistair, I am following you on the samba as well, between you, Doug and Alex, you doing a lot of research.
Do you have any idea about the color on those disc (with holes), worn or not. Since all of them have a slotted disc between them, it didn’t happen inside the VC. Do you think they got a heat treatment before being put together?
I got my used (but good) VC last week but I am not planning to swap it now (sorry, too cold, snow and tired of the van, I need to take rest this winter….) but will do during spring certainly and get some oil and seals directly from Germany when we’ll go there to see my family in Europe.
Good luck and thanks for what you are doing, you guys are helping all of us!
#5 by albell on December 4, 2011 - 7:56 am
I can’t say for sure if the colour on the plates is the result of heat treatment, but it sure looks like that, especially when you look at the edges of the plates where you can see blue. I have read that the plates in a VC can have a nickel plating on them. I don’t know if the Vanagon plates have that, if so I guess one could find out what temperature would create the colour (oxide) in the nickel. Come to think of it, that is worth looking up.
I still have not resolved which plate pairs touch and which do not. The wear pattern tells you, but that pattern is not consistent on every plate pair. I’ll try and explain that further in another post.