Monoshock cafe 'esque build

[mcarrel44]

Hello

I am working on my first build and have encountered my first problem, I'm hoping someone can help me out. First let me post some pics of what I've done so far.

The problem I am having is that the shock can't support the weight of the bike. It is off an '08 Yamaha R6, which has a linkage system to reduce the leverage the swingarm puts on the shock. When I take it off the stand the bike nearly rest on the floor and the shock travel is real mushy for lack of a better term. I know that when monoshocks first came out they didn't have the linkage system on them but they were mounted differently so they acted on the swingarm closer to the axle. Any suggestions as to maybe a different shock I could use, or would it be possible to respring this shock with something stiffer, it would have to be in the 30kg/mm (about three times the 10.5kg/mm it is now) range to counter the swing arm leverage. If I could find a spring with that rate would it mess up the damping action of the shock. I could build a linkage setup, but I like how clean the rear end looks without a bunch of bits and pieces back there. I also included some pics of the swingarm modification, and the lower shock mount.

Any help would be greatly appreciated.

Thanks,
Matt

 

[gentlemanjim]

Nice set up - truly my kind of build. I don't see why you cannot installl a heavier weight spring if the shock you have allows for that. I had a Ducati with direct mounted shcik and worked fine. Progressive, YSS and Hagon all sell springs separately. In fact the YSS guy will be the go to person he can advise you on a specific recommendation. Here's his link: http://yssusa.com/products_oils.html

 

[Jack]

What looks good and what needs to be done for that shock to be functional is a different story. If the R6 came with a linkage system then use it,after all the engineers designed that suspension system for a specific reason. Another alternative shock would be to install a FZR system but requires the bottom leverage arm that connects to the bracket needs to be installed at the bottom cross section of the back bone between 60 and 62 degree angle for the correct apply ratio leverage and depending on what swing arm you decide to use,you must figure in the S/A angle during moc-up of the brackets.

 

[Beau]

My knowledge tells me the shock going straight up is gonna do weird things. But I can't see what's happening in there soo...

Heavier springs should help. My guess is that the original set up had some sort of leverage built in so the spring didn't need to be as stiff. Not to mention the bike may be a little lighter.

My guess is this. The shock is almost vertical with no weight on the bike. When you put weight on, the shock is sagging to where it wants to be. But because your lower pivot is almost directly under the shock, the amount of travel you have is from the sag. If you moved the top pivot towards the front of the bike more it may help things out.

Is the spring actually compressing from the weight of the bike? Or is the swingarm just moving the shock back and forth?

Make sense?

 

[barkcollar]

might have to do a setup similar to this to get the most benefit .

 

[atomic22]

So barkcollar, I read where you put a bump stop on and another spacer or something. Just wondering what the difference is, since I'm going to be doing the same mod over the winter.
Since I bought the shock for $25 I'm not too worried about going a different direction.

 

[barkcollar]

If I was going to do the cafe route I would of made the correct changes to use the shock correctly.(or for it's full potential). Since I went the bobberish look, the fact that it sits on a bumpstop and really does not use the shock(it's just for looks) is ok with me.
If I did it all over again I would of made it right.
But Hey! that's what makes us better builders.
I have no teacher. I'm figuring it out as I go.
No matter what I did to the shock at that angle it didn't work.

 

[Beau]

http://www.650rider.com/index.php?name=Forums&file=viewtopic&t=7316

 

[atomic22]

If I was going to do the cafe route I would of made the correct changes to use the shock correctly.(or for it's full potential). Since I went the bobberish look, the fact that it sits on a bumpstop and really does not use the shock(it's just for looks) is ok with me.
If I did it all over again I would of made it right.
But Hey! that's what makes us better builders.
I have no teacher. I'm figuring it out as I go.
No matter what I did to the shock at that angle it didn't work.

Thanks for straightening it out...get it...straight as in the shock

So basically you have no spring in your shock. Good to know.

 

[barkcollar]

no. I could space the bottom bracket up. but it would make the bike higher. nit what I'm looking for on this bike.lower the better.
good luck

 

[barkcollar]

Beau, thats the pic I was looking for. awesome bike
Thanks for the find

 

[mcarrel44]

So I got the rear shock working. I ended up using the linkage and dogbone off the r6 and made some new top mounts. So a little clean up work on the mounts and it should be good to go. Now on to the next project.

 

[mcarrel44]

forgot to include the photo

 

[Yamaha_chop]

Could I get some more shots of the linkage setup?

thanks
Sky

 

[mcarrel44]

yeah ill try to get them up in the morning when the light is better. Basically I used the triangular lingake of the r6 to attach to my swing arm the shock and the dogbone and then the dogbone and shock to the upper mount

 

[atomic22]

yeah ill try to get them up in the morning when the light is better. Basically I used the triangular lingake of the r6 to attach to my swing arm the shock and the dogbone and then the dogbone and shock to the upper mount

Dude, I really need some pictures to understand what you are doing.
I mean cool that you got it to work, and it looks awesome, but

Just kidding, I like where you are going with the whole thing...hoping not to sound like a dick.

 

[barkcollar]

Hell yeh!

 

[mcarrel44]

More photos as promised. I may still tweak the shape of the linkage to set the ride height a little higher and to soften the spring just a bit.

 

[Yamaha_chop]

Appreciate the extra pics, thank you

 

[barkcollar]

Awesome you got it to work out!
this is what I'm going to try.