Topic: My last twin disc question....maybe

[timtune]

I'm looking to add the second disc to a early (72-73) cb750K. I've read a great deal about the speedo drive - getting drives from different years, using hubs with 2 flats, buying aftermarket kits and various ways to modify them.

THEN I caught something @bryanj had posted which was the same idea I had earlier. Chuck the drive in the lathe , cut off the tabs and turn down the outer diameter so it fit inside the brake disc and then simply mount the drive to the hub by drilling and tapping 3 small holes to bolt it on. 

I have a lathe and this method seems very straight forward. Is there any reason not to go this route

[bryanj]

Non at all but be carefull as the later drives are actually 2 piece bonded together with a rubber like substance whilst early ones are all metal.
There is another post at moment about a 500 and in that is a link to a ready to use part, about $30 from memory, dependa how much you value your time

[Don R]

 I did one like that using two roll pins. This is my last answer, maybe. L0L!

[timtune]

Thanks. This might open a can of worms but I have two drives. On the upper portion (smaller diameter) with two tabs that go into the speedo unit one has a groove just under the tabs the other does not. Both appear to fit in the speedo unit. Was the groove for an o ring? (that's missing??) If so do I need one?
Don R - you used two roll pins instead of bolts. Was this because once assembled the drive was captive anyway.

[PeWe]

I added a 2nd brake early 2016 on my K6.
I got much info in an old long thread on this forum about dual brakes. (Maybe 2 old threads.)

If you find that thread you'll find all you need to know.

[Godffery]

 If you modify one of those yourself, Here is a pic of what it should look like when your done.
 https://godfferysgarage.com/wp-content/uploads/8-Speedo-Drive-Plate.jpg
 I make these for the Twin Disc Kits I sell and this particular one is using roll-Pins rather that countersunk screws.

[bryanj]

Never seen an O ring in one and only saw a two part drive for first time last year

[Don R]

 The drive hub is trapped between the wheel hub and the speedometer drive, it just needs something to make it rotate with the wheel.
  Someone said his works with no screws or pins. I prefer knowing it is fastened somehow but whatever works, right?  The 750 Hondamatic wheel I recently took apart had the two-layer drive hub and o ring.
  This was my last answer. Maybe.

[bryanj]

Never even seen an A in the flesh never mind spanered on one so cant comment on that

[Don R]

 Honda didn't make more special parts than they needed to, I think A's and K's shared most brake parts made that same year. In 75 and 76 I'm pretty sure F and A had the same front brakes.

[bryanj]

They two part plate i saw was from a later 550 so could be same yeay

[timtune]

If you modify one of those yourself, Here is a pic of what it should look like when your done.
 https://godfferysgarage.com/wp-content/uploads/8-Speedo-Drive-Plate.jpg
 I make these for the Twin Disc Kits I sell and this particular one is using roll-Pins rather that countersunk screws.

I wasn't thinking about the fact that there may not be space for a bolt head protruding from that surface.Thanks for the head's up.

[timtune]

Honda didn't make more special parts than they needed to, I think A's and K's shared most brake parts made that same year. In 75 and 76 I'm pretty sure F and A had the same front brakes.

We know different Honda companies. Although hands don't change size levers are smaller on smaller bikes - just the tip of the iceburg......

[Don R]

 The story was that Mr. Honda made the 750 bigger after seeing a large (Italian?) police officer get off of a small bike. He assumed that the majority of Americans were also that big. I happen to fit a 750 pretty well but my brother, not as much.