As for the part about the forks only being held together by an 8 mm bolt (a larger boltsize will not contribute to lessen the forkflex), well that is what many newer bikes use also without anything else then a plastic front fender (by newer I mean eighties and mid ninethies bikes).
Nah mate, I never thought the size of the screw holding the damper rod to the slider made any difference to the handling, what I was trying to illustrate is that there is nothing securing the fork tube to the slider, allowing the slider to rotate freely around the fork tube, if the two sliders aren't tied together by the fender, or a brace.
The fork flex comes from the upperlegs twisting and bending due to being underdimensioned (hello forkbrace or USD-forks...) or to much free play between upperleg and slider (hello new bushings....)
Well....... not entirely. Sure, 35mm tubes are pretty small by todays standards, and the longer a piece of pipe is, the more chance there is of flex, but the main culprit is as described above. As far as "bushings" go, Honda ditched them after the K2, and considering that the later bikes (particularly the F-F3 and K7-K8) were arguably better handlers, the point is only applicable to the 69-72 model year range.
So, sure a brace will help stiffen up the CB750´s underdimensioned forklegs that has been worn through 30 odd years of use and abuse.
I'm having difficulty understanding how 30 years of use and abuse will decrease the OD of the fork tubes, when they are only coming into contact with rubber fork seals and well oiled soft alloy sliders or brass bushes? I must go measure some and report back..........
My point is though, that you can run a well set up CB750 sans forkbrace without fearing that it will throw you into the nearest ditch as soon as you starts to push it.
By well set up I mean:
- good forkbushings
- correct amount of oil in forklegs
- good steering head bearings
- good rear suspension
- straight wheels with correct spoke tension
- good swing arm bushings
- good wheel bearings
Well, seperate bushes were only used in CB750's from K0 to K2, so that point is not applicable for bikes from 1973 - 1978, and while all the other tips are good points and widely accepted as standard maintenance items, they're largely wasted if you're going to ignore common sense and run "sans fender" or brace.
Every bike should have these items gone through before they start having forkbraces and steering dampers thrown on them.
My guess is that many skip servicing these items and go straight to bracing both forks and frames.
Cheers
Daniel
As I mentioned above, most of us who have restored their 30+ year old bikes will have "sorted" our suspension as part of the build, so installing a brace or a steering damper (another very useful addition) isn't "throwing" something at a poorly maintained bike, but rather, building on what we've got, and improving our bikes as we go.
Now I've got no problem at all with guys who lean toward the "form over function" route, who prefer clubman handlebars, dummy tank extensions and unbraced fibreglass fenders etc to express their art. Sadly, because I was born without an imagination, I much prefer mechanical proficiency, to shiny things.
I really enjoy going to classic and post classic race meets, and while some of the race bikes that I see circulating at incredible speeds are not fitted with front fenders, they're all wearing some kind of fork brace. Like I said before, If you don't think you need one, then you've never ridden your bike to it's limits. Cheers, Terry.
