Metz Drive-Disc Removal

[ThreePedals]

The large flat disc that drives the friction wheel on my recently-acquired 1915 Model 22 Fore Door needs to be resurfaced. I see two collars and some fine threads before it disappears into the bearing. Perhaps someone would be kind enough to give me some sage advice on removing the disc without fumbling with undo force and possibly damaging it. How was it assembled and how do I carefully remove it?

[Luv2Wrench]

Please post a picture so I can remember what it looks like and make sure we're talking about the same thing.

[ThreePedals]

I’m out of state at the moment and will return home next weekend. I’ll take a close-up shot of the backside of the disc as it connects to the driveshaft  then. This shot is probably no help. And yes, that is original 106 year old wood and upholstery as decrepit as it is. Thanks for chiming in.

[Luv2Wrench]

I believe that disc is two discs, one is the bigger casting that connects onto the drive shaft.  The other is a simple disc attached to the casting by the slotted screws around the rim.  Remove those screws and the disc will then come off.  Probably best to replace the disc rather than resurface it.  They were made to be removable so you could replace them.  I believe you could flip them and then replace them.  I know you could do that with the style my 1913 has but mine is a bit different from your's.

 

[ThreePedals]

Your advice was spot-on. I decided to remove the aluminum plate from the cast iron disc. Luckily, the 20 screws behaved nicely. Interesting note: they are non-ferrous (presumably brass) 1/4-24 screws. Once removed, I could see that the plate had been reversed once before, so I will be replacing it. The added bonus was that it became obvious from this new vantage point exactly how the cast iron disc is mounted to the drive shaft answering my first question. Included is a photo of the creative attachment.

So now that I’m in fabrication mode, does anyone know what specific flavor of aluminum, speaking metallurgically, that would be best suited to the task?  My call to Paper Pulleys Inc. did not yield any suggestions as to the best surface from which to drive their friction material; they stay firmly on the driven, not driving side of the equation.

[Luv2Wrench]

I remember hearing it was "cast aluminum" but I don't remember where I heard/read that nor do I have any more detail.  McMaster-Carr has a couple different types of cast aluminum 

 

https://www.mcmaster.com/cast-aluminum/

 

The "Impact-resistant Marine-grade 5083" sounds pretty interesting since our disc are outside.  The MIC6 disc made from 7000 series seems convenient as you can get it as a disc.

If you have an old-school machine shop nearby you might take it to them and they might be able to tell you what it is.

 

[ThreePedals]

I like it, thanks. The original disc might very well be cast; it just has that feel. Of course, it measures 17” in diameter, though there is clearance for an 18” disc. Heck, that could add a mile an hour or two! I read somewhere the Model 25 employed a slightly larger disc.

 

As an engineer myself, this has become another fun science project. There is an engineer out there somewhere who knows the best solution to this spinning friction, transfer of mechanical power stuff.

 

My research turned up a potential source of information on friction systems with whom I may confer next week. https://www.rowlandcompany.com/about/ On the About page, the company claims to be the Problem Solver for any situation that involves the transmission of power from a driven force to a driving force (Although that sounds backwards to me, I’m pretty sure we’re talking about the same thing). Under the Products tab, Friction and Wear Materials, they mention re-lining obsolete friction discs. Stay tuned……..

[Luv2Wrench]

The trick with the friction disc is you don't want it to slip.... but then again... you do!!  The disc motion is circular but the friction wheel's motion is linear (where they meet).  Toward the center of the disc this is (obviously) much more of an issue.  A good visual image of this is what happens when the paper pulley is right in the middle?!  Metz had the notice to apply only as much pressure as needed as more pressure would add strain to the engine as it had to overcome the additional load of tearing apart the paper pulley.  

 

Let me know what you end up doing and you experiences with it.  I hope to be fabricating one for my car in a year (or two).