Monoshock Angles & Measurements.

[GQ88]

Hello Everyone,

I was hoping to get some insight on a monoshock conversion I am about to have done on my 85' VT700 Shadow. I've read some forums on such conversions but I never really got any concrete information on how to go about doing calculations so that the angles, and measurements will be correct. I would really appreciate it is I can be pointed in the right direction on this. The build has been done before in the attached picture, but I don't want to have the measurements eye balled and have to regret it and have the work re-done.

Here's what I'm working with:
For the monoshock I bought the 428 Series Shock from Progressive Suspension.
http://www.progressivesuspension.com/product/1418/428-series-shock

I'll also be using 1 inch Chromoly, and will be reinforcing the swing arm as much or more than the one in the picture. Here are more picture of the previous build.

http://motohype.com/?p=478

Thank you!!

 

[xb33bsa]

you cant learn this on a forum, buy the tony foale stuff,read as much as you can otherwise as well and educate yourself
that bike in the image you show is a deathtrap
http://www.tonyfoale.com/

 

[sav0r]

With some low level calculus and trigonometry you can calculate out most of the wheel rate stuff you need to make it work. That said, pen and paper or CAD is really the best place to start with these types of things. I'm not sure about motorcycle specific books, but there are lots on car suspension, much of the information would be applicable.

 

[GQ88]

Hey Guys,

Here's an update to my build. Only the seat pan left, which will be done in about a weeks time. Thoughts and input are all welcome.

 

[xb33bsa]

aint gonna fly that shock mount is midway on those tubes which will flex too much and fail

 

[xb33bsa]

that is if the upper shock mount itself or the flange at the final drive doesn't fail first
you are totally in over your head it is a horribly ill conceived design throughout
one can only hope you never get it on the road,lest you hurt yourself and innocent civilians

 

[cxman]

you need some help this will not go well and it will hurt you

there are forces working against what you have built that will break it and shear off your upper mount

you need to reinforce and redesign your mounts

you need to look up plug welding and do plug welded inserts in your frame joints

do you know a engineer or a professional fabricator ?

 

[lil beast]

Whats the spring rate? I wouldnt trust the other guys build to be honest, you dont know if the guy is has ridden it or properly tested it. The weakest point for me is at the top end, too much force on those two little tabs and there isnt a whole lot of travel there. What's the first thing thats gonna go when you bottom out?

 

[focusinprogress]

the rear mounting point isn't TERRIBLE if you beefed up the mounting point more. for the front mount, I would have turned the eye of the shock 90* and made it fit in the center leg of an "H" bracket so you have two crosstubes across the frame rather than one, and the bolt could go through a beefy bung on the top leg, the eyelet of the shock under that, and then a beefy bung in the bottom leg.

something like this:


/ \
/---I---\
/----I----\

where the shock would mount between the two "I"s