Topic: Comparison of disc sizes 77 750 F & CB 500-4

[754]

Someone a few days back was asking to ID a wheel, it was 77/78 F.

He wanted to use it on a 500 4 with dual discs. I  suggested that if the diameters were close it may be possible with a bit of machining, then someone said no way.

 If some can provide the diameters, and they are close, I think it may be doable.. it would save a huge amount of unsprung weight IMO..

[bryanj]

Its not the diameters its the bolts the 500 and 750 to 76 had 6 bolt rotors the 77/78 had 5 bolt thinner rotors

[754]

Actually I meant whole wheel with comstar to save weight, discs are much lighter.

 The total width of a 750 dual  from disc to disc on outside is within 1/4 inch of the disc to disc on the F wheel.

 Because the  swing brackets on a 500 are so thick, you can mill 1/8 off at least one side and correct the spacing... easily.

 The other problems will be swept area & diameters.

 If it works, its big gains for reasonable $

[bwaller]

The overall diameter should be the same or very nearly, but the latter discs do have more offset, so it'll take some creativity but just another challenge.

[754]

No offset problems if you use the wheel they came on.. these f duals are seriouslly lighter than the old ones.

 The biggest problem, I can see is you have to live with the Comstar................................................running...

[bwaller]

I'm taking another direction with stock hub and discs (just under 5mm) on 750 F3 forks. Need to space the rotors out or calipers inward.

The caliper hanger brackets are beefy on the 500's. Milled a pair on the last project to align with thinner Suzuki discs.

[754]

Which calipers? easy to shim the 3 point mount 500 & 750 calipers imwards..
 and easy to cut 2 discs with bolt pattern to move discs out.. use longer bolts.

 I have done gobs of adapting, so has fishhead..

[bwaller]

Which calipers? easy to shim the 3 point mount 500 & 750 calipers imwards..
 and easy to cut 2 discs with bolt pattern to move discs out.. use longer bolts.

 I have done gobs of adapting, so has fishhead..

Not sure yet, depends on what the class rules allow. Maybe GL, maybe Brembos, definitely not the originals. A couple easy brackets with F3 forks.