Honda CX 500 Forum banner

21 - 40 of 67 Posts

·
Super Moderator
Joined
·
4,209 Posts
What have you done to strengthen the swing arm at the lower shock mount? It seems to me that that part of the swing arm is not designed for taking such a load.
 
  • Like
Reactions: Randall-in-Mpls

·
Registered
Joined
·
221 Posts
Discussion Starter #23
Okay some more pictures...I've been asked a few times if I really know what I'm doing here...and the answer is "of course not!" But I thought I would make it a point to EXPLAIN why I went with this shock, in this location, at this angle,etc and so forth. Everyone who's gone and done something like this seems to want to keep all their math and details a secret which leads me to two conclusions:

1. They made it up to look the way they wanted because the bike was meant to be looked at, not used...a theory often supported by the ties on these things.

~or~

2. They don't want to give away their hard earned work.

Honestly I'm not offended by #2, and I don't care enough about #1 one to be concerned with it. I'm going to try and make it a part of this build to explain how I'm doing the single shock, how it's working, what should be done different, what changes I make, and so on.

So before I went to my pile of shocks I measured travel of the rear from my desired ride height up to the extreme of the swingarm could muster. At the brace in the arm there was just under 2.25" of swing...it was close to 54mm.

I've got a large collection of rear shocks and strokes anywhere between 40mm and 90mm. I wanted an eye-to-eye shock for ease of mounting...I don't want to have to press a bearing/bushing into the arm to make it work. That left me with the CBR954RR shock and a 2007 YZF-R6 shock. The R6 shock is sprung at 10.8kg/mm and has a 67mm stroke. The 954RR shock is spring at 14.8kg/mm and has a 57mm stroke.

I went with the 954 shock because it was almost exactly the right stroke and is already designed to work with a considerably heavier spring. What's more is that the linkage on the R6 is pretty long and the bike has a slightly shorter travel...which means the stroke on it is going to slower. The 954 shock was part of a short arm system that's already designed to be under high stress and moved rapidly (shorter stroke). It just made sense to me to use the 954 shock (from my collection of old used stock shocks). I'm sure there are better options out there.

Now as said earlier the spring is a bit soft, but there are plenty of options out there for replacement springs. I pulled the shock to maximum compression (minus maybe 2mm...the next tooth on the winch was hiting the bump stop).







This gives me just over 7" total wheel travel in the back...which I believe should be sufficient...but it is still quite a bit shy of the mechanical limit of the arm. Means even if I completely bottom out the shock I'll still have a little room to keep things from breaking.

If my math is right I believe that what I need back there is a 16kg/mm spring. I'm going to wait until I have the tank and everything else in place and then measure for the appropriate spring.
 

·
Registered
Joined
·
221 Posts
Discussion Starter #24
What have you done to strengthen the swing arm at the lower shock mount? It seems to me that that part of the swing arm is not designed for taking such a load.
Just to note, when I pulled the arm up to full compression there was no flex in it at all. I'm still bracing it, but it is pretty strong for what it is.
 

·
Registered
Joined
·
130 Posts
My hat is off to you guys who tackle the forks first......
My build will tackle pretty much everything but forks...
Until next year...
 

·
Registered
Joined
·
130 Posts
But then the can of worms is open on wheel choice;
1) use modern front cast wheel that goes with those forks
2) adapt Comstar to fit modern forks
3) go Cognito moto custom spoke wheels (front & rear) $$$$$$$
I can't commit to which of those choices I will make.
I have been browsing for a set of forks to sit in my garage, until I decide...
 

·
Registered
Joined
·
1,021 Posts
I love the look of those gold anodized inverted forks for sure and those big ole dual disc brakes!
 

·
Registered
Joined
·
1,021 Posts
clip-ons look cool but un-ridable for me at this point.
 

·
Registered
Joined
·
221 Posts
Discussion Starter #33
clip-ons look cool but un-ridable for me at this point.
I have a harder time with bars that keep my back upright...it's like my spine compresses with every bump. But my wrists are also getting weaker the older I get so clip ons are getting tougher and tougher. Honestly I'm getting to a point where I have more fun building them than riding them.
 

·
Registered
Joined
·
1 Posts
I am going to have to get my vision checked. i think i see too many runners on that one! :confused:
 
  • Like
Reactions: D-Fresh

·
Registered
Joined
·
57 Posts
Curious to see how your route your pipes. Looking good!
 
21 - 40 of 67 Posts
Top