Topic: Somebody here with access to a CNC machine?

[Raul CB750K1]

I'm considering adding a second disc to my 750 K1. As opposed to later models, the caliper holder can't be simply bolted on on the right side; it needs some grinding, filing and using of spacers. The holes align, but the spacing is on the wrong side; it should be on the other side of the bracket, if you catch my drift, as the threaded holes are not in a "flat" plane.

I was thinking that the most elegant solution should be to have the part "digitized", then "mirror-reversed", and then machined on a CNC. How expensive could it get?

[bryanj]

2-3 hours of computer time pluss the same CNC time at megabucks an hour!

[stay youth]

I don't know where you are located but you should try bringing your project to a local school that is training people on CNC machines. I bet you could get it done for cheap. Is the part just a flat cut? What kind of metal did you want? Aluminum would be the cheapest solution.  I know a guy here in California that could do it for cheap maybe.

hope that helps
mark

[754]

73 and up just a flat 6mm or so spacer.. and I dont remember anyone on a K2 or earlier EVER doing extensive work to adapt a 2nd disc.. and noboy in those days had CNC's in small towns

maybe look it over again..

[Raul CB750K1]

The Japauto that I recently saw in a museum had a double-disc setup so I took some pics. I had foresaw the outcome, so it was good to see it in the flesh.

As you can see, there are two mounting bolts in the back of the bracket. The top one has the spacer on the "wrong side". No problem, a spacer in the left side will suffice. But then, the original spacing makes the bolt go too much into the wheel. It doesn't touch anything, but still it is too much in my opinion. Easy solution would be to file the excess material.

The biggest issue in my opinion comes from the bracket holder for the brake line. Again, the spacing material is in the wrong side, forcing the bracket to be bent and the bolt to get pretty dangerously close to the rim. The fender tabs are also different in both sides, attaching to the brake bracket on the right side while on the left it attaches to the shock lower.

Well, I guess that if this was good enough for Japauto, it will be good enough for me.... 



P.S. Bryan, could you send me that doc about modifying the speedo holder bracket?

[bryanj]

Back in the mid 70's you could get, i think as part of the race kit, a "Mirror Image" bracket cast in Magnesium--A bit of overkill for a road bike! Trouble is that whoever had the wooden pattern probably slung it as it was small and not often used--The big ones tend to hang about as they are too big to throw!
Raul Its not the Holder its the drive plate and email on way

[Raul CB750K1]

Wow, DG, that brake setup is so shiny I had to put my shades on just to loot at the picture! 

Bryan, I recall having read in one of the technical datasheets you submitted to Glenn, that there was some shim washers to keep the caliper unit from "clonking". "While I'm at it" I will shim mine too as I don't like that clonking noise every time I go through a bump.

email received, thanks a lot!