Rear Mono Shock Mod.... How To?

Hi all XJers,

I have seen a few Mono shock has been done, and i like it! and I have to say the BEST one belongs to skylrk62! Also an awesome job he's doing to his XJ. Below is the link if you want to check it out!
http://www.xjbikes.com/Forums/viewtopic/t=35431/

I am starting this thread to gain more ideas/experience/methods tips and tricks on how to make/mod a Mono shock set up.

Any info would be awesome!

kinen1

 

Mine in progress. The top of the swing arm is off of a '83 XT550 and Its held to the XJ550 swing arm with 4 plates of 3/8" steel(2 on each side). Attached the R1 shock with spacers(welded in place) on the swing arm and fabbed out 2 brackets to hold the shock to the cross-member on the frame.

 

Do some research, most people just fab up some brackets and find a shock the right length with no thought to spring rates or suspension geometry

Get a hold of some books like Tony Foale Motorcycle handling and chassis design http://www.tonyfoale.com/

Guesswork might get you there but it wont work as good as something that's had some proper thought and design put in to it

 

Also, designs with the shock directly bolted to swingarm & frame are likely easier to install than ones with linkages (plus some linkage designs can result in a lot more stress being put through the frame than others)

 

I am new to motorcycles and the cafe/modding has bit me!

Hey onetrackstu, thanks for that! if u can post some pics of ur mod!? thanks in advance.

kickaha, i will read it up to get a better idea, (never knew there was a book) thank you kickaha.

Rboke, i was only thinking of direct mount from swing arm to chassis (grin) i m only small under 80kg .

and last if any one has done this mod and got pics pls post pics up!

kien1

 

check out the link in my post. click on the word "mine"

 

Yeh i had a look. Have you got any pics on the mounting of the shock to the frame? if so please post them.

thanks

kinen1

 

Actually I just remembered I owned this rough old beast a few years back, it's a 1981 Suzuki DR400 with Honda CR500 front & back ends, that was a monoshock conversion. Was done when I got the bike & was quite simple on that thing, just a plate welded under the frame tubes & the shock spindle/bushes bolted straight to that...

 

This is a picture of the frame laying on the side. I made some tabs and then welded them to the fame. I forget the thickness of the tabs(I think 1/4).

 

awesome.

thanks guys

kinen1

 

Hi all,

I have been searching around for the swing arm to do the mod...... but parts are EXPENSIVE in Australia. So I have spoken to a boiler maker and we have deiced to bend a metal tube (not sure how big the tube is gonna be but i m guessing not much bigger than the frame tube) weld the tube to the XJ swing arm plus support brackets, (we will look at the angle of the shaft drive when we are there!) then fab something up for the mount on the cross-member of the frame!

In the mean time I will chase up some tubing and a mono shock.

I will keep this thread update along as I make progress.

have a nice weekend all.

kinen1

 

I actually just posted a (blury, non centered) picture of my monolever style conversion. I call it that instead of monoshock because its more like the BMW monolver (shock runs from pumpkin to side of frame, to one side of wheel) than a monoshock (shock runs from swing arm bracket to frame, in front of wheel).

The pictures I put in my post suck because its an overview of the project, let me see if I can find better....

 

sebwiers, that looks awesome, I think you are the 1st the do this mod (monolever)! you have got some serious welding there!


thankk sebwiers.

kinen1

 

Thank you. My welding skills were actually pretty bad when I started the project, and the design was really half assed; this is basically the second build. I ended up wrecking one swing arm due to poor lower shock mount design, and adding WAY to much re-enforcing (I picked up a spare on ebay going into the project so I'd have a fall back). I also had to chop off the first rear frame support I built after I bolted it all up, as I discovered the support blocked the shock motion- when I positioned it, I forget that those parts MOVE!

There's still some work to do. I plan to add some frame bracing to stop the shock from twisting / flexing the mounting. While the shock presses down on a plate that rests on top of the pumpkin, I'd like to also have an attachment running back to the pumpkins shock mounting point, but that will take some mill work to produce a properly fitting removable bridge - a skill I plan to pick up this winter.