'82 Gs650G monoshock conversion

Bonehead

Bonehead

I am wrong... A lot. Don't worry, I know
After looking for a well done monoshock Gs650G (like mine) I found a well done, 3-link system that looks VERY doable in my opinion. I just love the way it changes the stance of the bike, and cleans up the rear end.
The top mount is a bent plate welded into place with a hole for top of the mount, then a clevis for the shock to mount to. The the main 3 link mount (the part that pivots) is welded to the crossmember of the swingarm, dead center if my eye serves me right. A stationary point is also added to a crossmember of the frame right above the swingarm. Am I right in saying, just so I understand the physics of it, that this is just a modern rear suspension set up turned upside down? Just trying to wrap my head around this whole conversion I am undertaking :eek:
I just have a couple of questions on this modification...

- Ground clearance? I was wondering how much of a drop I should expect with this conversion.
- The frame modifications are obvious, but will I have to take the engine out of the frame?
- How should I prep for this conversion?
- Frame is cut right at the back of the engine, not just the subframe (like seat and back). Would it be possible to mount it without cutting the whole frame down?
Here is the blog I found it on (click this link for many many pictures and a few videos the guys that made it did)

Here is a picture of what I want to accomplish
mg_23151.jpg
 
you are asking way too many simple questions to be attempting this mod
just photoshop your bike and be happy
 
xb33bsa said:
you are asking way too many simple questions to be attempting this mod
just photoshop your bike and be happy
Click to expand...

Man you just love to post useless shit. Would you rather me buy a shitload of bolt on parts and be happy? I'll "attempt" whatever I feel is in my power, and usually I succeed despite my lack of knowledge. I don't work at a motorcycle shop for nothing.
 
i am trying to help you
you are far too ignorant to attempt that kind of mod.period
do some serious reading about suspension design tony foale has a very good book for starters
you can't learn this shit posting questions on the internet
read some books on suspension setup, motorcycle geometry
the biggest fail is you want to do it for a LOOK
that you posted, for an example, a complete fucking deathrap is worrisome and then you ask how low it will make the bike ? good lord educate yourself before you get hurt
yes i would rather you just buy a set of hi quality shocks spend the money and enjoy your motorcycle instead of trying to make it something it isn't
 
Here's a working link.

http://3onthetree.wordpress.com/2011/06/17/closer-look/

It looks cool, I'm not sure the seat works though. It appears in several photos that he uses a steel tube to prob it up. The bike doesn't have carbs, curiously. On top of that, I don't see any swing arm bracing whatsoever. I doubt that your example bike functions. Adding a monoshock requires a significantly stronger swing arm than a twin shock bike would have, which might be tough when one half of the swing arm is a drive shaft. Is it doable? Absolutely. It's going to take some engineering though. You should try contacting the owner of that blog and get some info directly from him, perhaps he has made more progress since these photos.
 
Here is a picture of what I want to accomplish
Click to expand...

the picture you showed has no suspension or frame at all....The shock has no place to mount, and the frame looks severely compromised in strength.

I have to agree with XB on this...You aren't asking the right questions...If you build anything like what is shown in the picture, do not make the engine runnable as the bike will be a dangerously compromised machine.

You may work at a bike shop, but engineering a frame that properly distributes the stress of the suspension, and designing the fork takes more than "working at a bike shop" experience and knowledge.

You are asking for appearance and stance answers, not strength, proper geometry, etc.....

Since the front end was designed for the specific height of the rear, many changes to the frame and front suspension will also be needed to get the handling right (safe).

The geometry and spring rate for a articulated rear suspension require some serious math skills to do right. No skills are required to do it wrong.

The articulated shock mounts are not done for looks, but for a rising rate sprint rate....

Good luck on your endeavor, but I suspect, in the end, you will create an un-ridable bike, that can't be restored. I find that sad.....
 
Sav0r said:
Here's a working link.

http://3onthetree.wordpress.com/2011/06/17/closer-look/

It looks cool, I'm not sure the seat works though. It appears in several photos that he uses a steel tube to prob it up. The bike doesn't have carbs, curiously. On top of that, I don't see any swing arm bracing whatsoever. I doubt that your example bike functions. Adding a monoshock requires a significantly stronger swing arm than a twin shock bike would have, which might be tough when one half of the swing arm is a drive shaft. Is it doable? Absolutely. It's going to take some engineering though. You should try contacting the owner of that blog and get some info directly from him, perhaps he has made more progress since these photos.
Click to expand...

The seat is just a skateboard propped into place, and the missing carbs do indeed seem curious. I have no fantasies of this being a working model. I'll have a serious conversation with one of the guys that helps fabricate pieces/builds some of the bikes we sell about the geometry change as well as frame design.
Exactly what I did. Have yet to hear an answer though :-\ I have a feeling the guy got too deep and just left it like it is or abandoned it all together.

In all honesty, it is something I would like to do. If the input far exceeds the output, I will gladly call it a day slap some works performance shocks on it. However, this being a test bike since the beginning I can use it to see what I can do. If I can't, I can't and will leave it as is.

ps sorry for the snappy comment I understand you guys are trying to save me from myself, but I want to test the limits of what I can do. Simple as that. And, see how far my CAD design skills have come.
 
If you are just wanting to "experiment" with what you can do, I recommend finding a basket case bike without a title to screw around with. That way you can get your hands dirty but you are only out a couple hundred bucks if it doesn't work and is a complete fail.

Scottie J
 
If you have the time, spare cash, and tools to get the job done, I tend to think you should attempt it. It's something you want to do, so do it. At a minimum, you'll learn some lessons a long the way. You didn't come off snappy, and I hope I didn't either.
 
That pic of the guy showering the carbless engine with sparks is priceless.


http://3onthetree.wordpress.com/2011/06/17/closer-look/
 
If you want to do this you're going to have to study shock geometry and learn a bit of trig. Figure out what type of shock -- linkage, direct mount and etc. All have pros and cons.

Most of the mono-shock builds you see around are NOT functional. They are closer to sculptures than ridable bikes. I have a working mono setup which I have had a ton of assistance with and I'll say that for what I've put into it I would've been better off buying a brand-new set of Ohlins twin shocks. Not only would I have a better handling suspension I'd have saved a bit of money as well. However I knew from the start the mono-build was not a rational decision -- and boy is it ever fucking awesome.

If you're still dead-set on monos I'll include a bit of reference material.
The basics: http://www.carbibles.com/suspension_bible_bikes.html
A good reference from the builds section: http://www.dotheton.com/forum/index.php?topic=19369.30
 
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