Single shock conversion

[Sharky]

Just wondering..as I have the 4-2-1 that will make the bikes rear quite wide...and having seen a few bikes with just a shock on one side I got thinking. :ummm:

As I have the fjr1300 swingarm (monoshock, and therefore deisgned for only being supported at the front)..could I run a single heavy duty shock off the diff side ?

Mmmmmm...food for thought...need to research the frame set up on these bikes (bmw for one has this system)

 

[one2dmax]

Yes, this has been done a number of times with the Vmax. Even parallel to the ground shock. I don't have many pics of this though.

 

[Redbone]

Here is an $11,000 option! I give you the 'OTEC' 330 Swing-Arm and Full Floating Suspension http://www.exactrep.com/acatalog/info_226_H.html
At least you might get some ideas from the pictures; at least they are free unless I'm breaching some sort of intellectual property rights or something!

 

[Sharky]

Looks like the cheap option lol

 

[Sharky]

All looking good.
Frame cross braced under rider seat area.
Couple of gussetts and all done.
My mate at Gazi shocks can supply a single shock with the right rating and valving

 

[one2dmax]

Did you see how we did the conversion? Nothing complex on what we did.

 

[Sharky]

I had a look Sean but couldn't find it...Do you have a link ?

 

[one2dmax]

Here you go

 

[Sharky]

Thanks mate.
That's more a mono shock conversion whereas I'm putting it on the diff side.

 

[one2dmax]

That's right. I'm trying to remember the other members name on here. His last posts showed a side mounted shock running horizontally.

 

[davesax36]

You should copy the otec side-mount one. There's at least one single sided swinger with single side shock in the optimal carbone galleries, too. Good luck finding it, though. I went through them again a couple weeks ago.

 

[Miles Long]

Does a monoshock arrangement provide better handling/suspension improvements over a dual shock setup, or is it a advancement purely based on aesthetics, or possibly cost-saving?
It would seem to me that dual shocks would provide a more secure attachment method for the swingarm, resulting in less flex.
But I'm not a MC design engineer.
Educate me, Great Ones.
Cheers!

 

[Sharky]

To be honest I dont know Miles.
I'm guessing the FJR arm is stiff enough as its a mono shock arm and by adding a shock to the diff it can only help.
The shock will be worked out by Gazi (locsl specialist company).
The decision was aesthetic as the 4-2-1 exhaust muffler comes in too close to put the shock on.

 

[one2dmax]

I think this was Prez's original build thread. Pics aren't working for me but they are quirky on my computer anyway.
http://vmaxforum.net/showthread.php?t=7162

 

[Sharky]

No pics on mine either.

 

[Redbone]

Does a monoshock arrangement provide better handling/suspension improvements over a dual shock setup, or is it a advancement purely based on aesthetics, or possibly cost-saving?
It would seem to me that dual shocks would provide a more secure attachment method for the swingarm, resulting in less flex.
But I'm not a MC design engineer.
Educate me, Great Ones.
Cheers!

I think part of the single shock design basis is centralization of mass. Also, with most single shock system they have a levered mount so they can control the progressiveness of the spring rate and shock dampening characteristics better.
Dual shocks are completely dependent upon the swing arm's movement so in a sense the shock action is limited and takes more abuse being directly connected to wheel action. Whereas the single shock system employs the lever to help control the wheel movement which reduces the work the shock has to do thus reducing heat fatiguing that plagued dual shock designs. The development of the piggyback shock reservoirs were adding more fluid to the shock in an attempt to keep them cooler, heat was a major issue back in the day.
Like you, I am no suspension engineer just have followed the development of rear suspension from the early 70's motocross teams moving the shocks up the swingarm to get more travel. I had one of the early yz250 that had the monoshock suspension with shock with the backbone of the frame in the form of a tube around the shock. That was a heavy, a top heavy bike but rode well on the trails and homemade mx tracks I rode on.

 

[Fire-medic]

Here's a shot of my friend's Slingshot GSXR frame he's converted to a SSSwingarm. It's a VFR Honda swingarm & a Yamaha shock. It's going to be a streetbike, he's got a big motor for it. As you can see, it uses a link. I think the linkage design is to provide a progressively-stiffer resistance as shock travel is used, by a factor of multiples of resistance and not a straight progressive rate.

I began riding offroad on a 305 Scrambler and quickly went to a Yamaha 360 I bought new (& still have). That was just before the long-travel double-shock designs came in and then the Monoshock Yamahas. I recall Yamaha ran a motocross series in FL during the winter before the start of the regular season, I first attended it in 1973. Yamaha was running titanium-framed twin-shock YZ250/360's which had Y-straps across the gas tank to hold it on. They were the equal of the other factory efforts. They had Pierre Karsmakers from the Netherlands as their open class rider and Tim Hart. The following year they were the only ones w/a monoshock, and it was just ridiculous, how much faster they were than everyone else. They would cruise at the front until about two laps to go and then Karsmakers would just run-away from everyone, and win by a huge margin.

Making our frames into monoshocks would require a lot of stiffening and additional framework, to be safe, and that adds weight. Yes, a 'wow-factor,' but nothing I am capable of doing, though I like to see the outrageous designs others choose. I'd like to see someone use James Parker's RAAD design that was used on an FZR1000-based sport tourer, adopted to a 'Max, w/a SSSwingarm rear. I've seen other rad Maxes online using some hub-steer design.

I think part of the single shock design basis is centralization of mass. Also, with most single shock system they have a levered mount so they can control the progressiveness of the spring rate and shock dampening characteristics better.
Dual shocks are completely dependent upon the swing arm's movement so in a sense the shock action is limited and takes more abuse being directly connected to wheel action. Whereas the single shock system employs the lever to help control the wheel movement which reduces the work the shock has to do thus reducing heat fatiguing that plagued dual shock designs. The development of the piggyback shock reservoirs were adding more fluid to the shock in an attempt to keep them cooler, heat was a major issue back in the day.
Like you, I am no suspension engineer just have followed the development of rear suspension from the early 70's motocross teams moving the shocks up the swingarm to get more travel. I had one of the early yz250 that had the monoshock suspension with shock with the backbone of the frame in the form of a tube around the shock. That was a heavy, a top heavy bike but rode well on the trails and homemade mx tracks I rode on.

 

[Sharky]

Ive been looking at BMW's...that was the inspiration.
Early models had the shock on the rear diff to the frame.
Later they moved the mount point forwards on the arm.
I'm looking at this as an option.
Primarily its for shock/muffler clearance issues, 2nd aesthetics.

 

[Redbone]

My 3" over swing arm has the lower shock mount moved forward ~2.5". here is a picture along with a couple pictures of factory Maico's which were some of the first to move their shocks forward on the s/a in the search for more wheel travel.



And here is a little history of the beginning of Yamaha's monoshock : http://global.yamaha-motor.com/showroom/offroadmania/ch3/

Early 70's Factory "Works" MX designs: http://www.vintageworksbikes.com/Worksbikeslist.html