Topic: CB450/550/750 forks, triple clamp, hub fitment to 400F?

[Speedy]

I want to upgrade my 400F to 35mm forks, but keep the same geometry (60mm offset) and the same period look (no modern stuff).  I narrowed the triple trees down to CB450 70-74 and CB750K to 76.   I know the bearing sizes are the same but are the sterring stems the same length?  I read somewhere the 750 is longer than the 450, but can't find the actual measurement of either.  It was posted that the 400F is 179mm (224mm overall)

Forks, which are simliar in length and look? I think I read the 750K are 2" longer than the 450, but I  cannot find any info on how the 550 and 450 measure up to the 400F?  Which is the better option, and are the brake issues?  A bigger disk would be good, or 2 (but another topic down the road, as are emulators).

Finally I woud like to put aluminium rims on this bike, so do I keep the 400F hub and make new spacers?  That seems like a cheaper option?  Not sure how these options affect the speedo drive.

I'll most likely buy this stuff off ebay and want to make sure they will work. Thanks.

[bwaller]

I thought I had everything to measure & answer your questions but couldn't find a 450 lower to measure stem length. The 750 stem is 264mm and you're right the 400F is 244. I seem to remember the 450 piece is longer than the 400? All the stems will be 30mm at the base so you could just use the 450 lower clamp and replace that steering stem with your 400F piece, (grind the weld, press out, press in & re-weld)

The fork spacing will be greater with the 450 triples but they are 60mm offset. You could use a 450, 500/550 or 750 front hub/spacers and any of those bikes larger rotors with the six bolt pattern. You can still use the 400F speedo drive for an 18" wheel.

I believe the 77/78 CB550 forks are the shortest installed height and closest to your 400F at 28.25" from tube top to axle centre. I was too lazy to run out to another building to measure a 400 fork length!

Have fun.

[Speedy]

Thanks.  I found a local deal on a 450 front end so I will start there. I still can't figure out why Honda put 35mm forks on a 450 twin and 33mm forks on a 400/4.