1982 CB750(C/F/K) Swing Arm Dimensions

[papi_sosaa]

Hi all,

I'm looking for the dimensions of the rear wheel and swing arm from a 1982 Honda CB750F.

I want to compare the differences of the 750 rear wheel and swing arm dimensions with the rear wheel and swing arm from my '82 CB650SC as I'd like to see if they can be used to perform a rear disc conversion on my bike with as little modification as possible.

Only thing I've found online, according to an eBay ad was that the Pivot Bolt for the 650SC is 16mm x 354mm

Part numbers:
1982 CB650SC
Pivot Bolt - 90121-460-840
Swing Arm (blue) - 52100-460-840ZA

1982 CB750F
Pivot Bolt - 90121-445-770
Swing Arm (black) - 52100-445-770ZA

Dimensions:
1982 CB650SC
Pivot Bolt - 16mm x 354mm
Rear Wheel Size = 16"

1982 CB750F
Rear Wheel Size = 18"

If the rear wheel is going to be larger, I imagine I will need to use longer shocks in the rear.

From the pictures I've seen online, they look similar except for the position of the third linkage (650SC = on bottom for drum brake, 750F = on top for caliper). That's just based off a visual representation though, no measurements taken.

The pivot section of both arms look like they're pretty similar length wise to the point where you might be able to get away with using the 650SC collar, bushings, and pivot bolt/nut to bolt the 750F swing arm onto the 650SC frame.

 

[papi_sosaa]

Updating this as I am gathering more measurements:

1982 Honda CB650SC

Chain (Pitch/Links): 530/106
Front Sprocket: 17T
Rear Sprocket: 38T

Frame Swing Arm Inner Length: 235mm
Pivot Bolt: 16mm x 354mm
Swing Arm Tube: 225mm
Swing Arm Tube Diameter: 34mm
Swing Arm Total Length: 570mm
Swing Arm Dust Seal Lip: 2-3mm
Swing Arm Bushing Lip: 2mm
Swing Arm Collar Length: 230mm
Swing Arm Inner Wheel Mounting Space: 255mm
Swing Arm Outer Wheel Mounting Space: 273mm

Rear Axle Diameter: 18mm
Rear Wheel Diameter: 16in

1982 Honda CB750F

Chain (Pitch/Links): 530/108
Front Sprocket: 18T
Rear Sprocket: 46T

Frame Swing Arm Inner Length: 254mm
Pivot Bolt: 16mm x ?
Swing Arm Tube Length: 241mm
Swing Arm Tube Diameter: 38mm
Swing Arm Outer Wheel Mounting Space: 282mm

Rear Axle Diameter: 18mm
Rear Wheel Diameter: 18in

 

[papi_sosaa]

Picked up a CB750F rear end. Will measure the swing arm and determine what and how much will need to be cut once I've punched the bearings out.

 

[papi_sosaa]

I managed to get the 750F wheel to slide into the 650SC swing arm by widening the arms just a tad and it looks like everything lines up properly.

I also cut the torque linkage bracket off the 750F swing arm and lined it up with where it will need to get welded onto the 650SC swing arm. So far the only custom modification will be the swing arm.

I also put the Cognito Moto rearset bracket on in order to gauge how long of a brake line I will need.

 

[JPenn84]

Hey papi! Just curious if you have any ideas of the compatibility between K and F models? I have a 78 750F and there is a swing arm for a 83 CB1100F. The guy says it will fit a 79 to 83 CB DOHC...just wondering if that would also work on my 78 F model. I appreciate any insight on this. I'm just now looking into the swing arm and I'm roughly 50% through my build. Thanks!

 

[papi_sosaa]

Sorry JPenn, I don't know too much about the older 70s bikes. I haven't worked on the bike since I made my last post so I need to review everything before I get back into it.