[ChopperCharles]

What's the maximum safe swingarm angle for the GL500? I'm debating re-mounting the shock on my scrambler to give me a little more ride height.

Charles.

 

[murrayf]

drive shaft u joint deflection of more that 4.5 degrees will result in rapid us joint failure

and remember its not just about the runout angle its about the time between failure at running speed

and a cx 500 drive shaft spends a lot of its time turning well over 5k rpm

increase the angle and you can half the ujoint life very quickly

and if you get to where with axle droop you can get into ujoint bind (near 25 dgrees) then bad things will happen very quickly

 

[ChopperCharles]

With the bike unloaded, sitting on the sidestand, I'm at 14 degrees right now. Loaded there is significantly less angle, but I don't have a helper right now so I can't measure it. Been this way for a few thousand miles. Driveshaft life is what, 200k miles? I can live with reduced life, but how reduced is the question.

Charles.

 

[murrayf]

uld not increase it much if you have 14 unloaded you will hit binding near 22 or so for sure by 26

and you have to allow for a bounce to unload the suspension fully you do not want a 10k rpm drive shaft bind

i wonder if we could figure a cv joint that would mate up

 

[dbjac]

I was looking into it for the potential to swap a BMW single side swingarm to the frame.

Definitely interests me, but I need to get my bike running before you all shun me off the forum! haha

 

[Randall-in-Mpls]

Murray,

A couple years ago you told me a limit of 7 degrees. When I calculated the drive shaft rotation at 60mph and checked an engineering reference, I got the same answer. Don't ask me what the reference was. It was something I found online.

My first suspension design was about 15 degrees at full extension. With a slightly shorter shock and different mount on the linkage, it's down to 10 or 12. I expect sag to cut that in half.

Unless the shock mount breaks while I'm catching air (which I don't plan to do much), it won't get anywhere near 20 degrees.


R

EDIT: I've been looking for a CV joint small enough to fit inside the swingarm's bell, but haven't found one yet. I assume the best source would be a front axle from an ATV, or maybe a microcar. It would need to be the wheel end, because the drive shaft already handles the plunge action.

 

[murrayf]

if you dont care about drive shaft life then you could go up 14 running 25 max WITH ONE caveat

i have never done a study of drive shaft angle to slip joint withdrawal as the swingarm moves up and down it slides on and off the final drive

it wont be sliding on to far as that distance is set by the zero deflection distance and that is not changing

however the sliding off /withdrawal distance will be increasing and i would check that you are maintaining enough spline engagement with the final drive

at 25 max i would make sure that was at full shock extension so it can not go over that in a bad rebound situation

then start monthly inspections of the ujoint under the boot watch for rust or shavings keep aware of any vibrations down the road

make sure you keep the slider grease