Topic: unidentified rear disc conversion, not sure how to complete it ('77 K7)

[stan.]

the previous owner started on a rear disc swap but did not finish, and i'm not sure how to complete the deal because i don't know exactly what is sitting in front of me.  i also have the drum setup still, so i could go back if this conversion is a poor one.  the master cylinder that is as of yet unattached looks more modern than the other components, but it looks like a bracket would need to be fabricated to mount it.  there was also a printed out ebay image of a swingarm in the pile of papers that came with the pile of motorcycle so i'm not sure whether the swingarm on the bike is in fact a K7 part. 

help!

[Wobbly]

Looks like the CB750F/F1 setup.

http://www.cmsnl.com/honda-cb750f1-super-sport-1976-general-export-mph_model14679/partslist/F09.html#results


The K7 swingarm is lacking the bracket that the F swingarms would provide to attach the brake.

[flybox1]

^ Probably why it was never finished.
Sourcing a complete K7/8 rear wheel and drum, axle, and spacers may be the easiest way to go.

[Wobbly]

You can get a used F-swingarm cheap--no doubt. Why not go for it? There is a thread somewhere here regarding the conversion. The Japanese specs K7 came with a rear disc too (maintaining spoke wire wheels--no Comstar wheels). But it used the F2 swingarm.

[stan.]

bike came with a drum brake'd wheel, presumably the original K7 one.   so if my current goal is to just get the bike running as soon as possible, is that the best way to go for now?

is the spoked wheel with the disc stuff worth enough to bother selling to someone else if i'm going to revert to drum?

[flybox1]

Its really up to you.  As your bike sits, a swingarm swap (add new bushings) isnt too much work if you want to continue with the disc setup. 
And it isnt much work to slide the K7 drum wheel in there.
Either way, you'll probably have parts missing, needing to be ordered.

[01Thomas]

You've got a 750 F1 brake caliper and bracket with an older swinging arm. Done correctly (?) (with F1 parts) the caliper will sit over the axle not hanging under the axle as in your photos. The brake stay will then connect with a lug on top of the s-arm, (not underneath as in the drum-brake versions).

Looks like the CB750F/F1 setup.

http://www.cmsnl.com/honda-cb750f1-super-sport-1976-general-export-mph_model14679/partslist/F09.html#results


The K7 swingarm is lacking the bracket that the F swingarms would provide to attach the brake.

[754]

I think you can use your arm ,just need to fab and weld brake anchor part..
Also you will have to weld mounts to mount the mastercylinder to the frame ...maybe pick up pedal and linkage if you dont have..
..but the stock stuff will go back on in under an hour..

[stan.]

seems like going back to drum is the fastest option for now. i don't have the tools to start welding up new mounts and things, and i'd rather get the bike on the road before starting in on any modification projects that i don't have to.

here's photos of a wheel that came with the bike, plus a hub that came with the bike.  the full wheel's drum looks pretty thrashed, but the hub would need to be laced up into the rim and spokes that are currently on the bike i guess?  any wisdom on the shortest path to riding? 

[seanbarney41]

do'h!  that's the wrong wheel...might still bolt in and function fine, but I don't know

[stan.]

can anyone tell if this hub could be laced up with the spokes and rim that are currently on the bike, in order to get the stock drum brake setup going with a minimum of expense and effort?

[seanbarney41]

that should work...is that a 17" rim?  Key is if both hubs are the same overall diameter.  Do you have sprocket carrier and brake panel?

[strynboen]

i gladly bay the disc- hub- and caliber and pump  but it are prob to kosty to send it to Scandinavia

 bay new stainless steel spokes and build your hveel using the rim from the disc brake hveel..but have you a brake plate( holding the brake Shues)( and reaktion arm)..for the drum brake hub ...spacers can be made by any maskinists in town..
those reversed comstars are not for 750...think they are for a 650 v2 gyllepumpe