Conversion to monoshock

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lcgtr

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Just thought Id share this with you guys
I was going through the graveyard of bikes for one last parts grab before they go off to scrap metal ant thought Id keep this swingarm

Conversion to monoshock

Conversion to monoshock

Conversion to monoshock


Its from an early 80's SR250 and is a good starting point to use on a Commando I think, looks a bit Vincentesque
 
Pretty neat piece of work actually but it don't provide that real advantage of mono shocks which is linked leverage system to lessen the total shock motion less than full suspension travel so less fluid heat thinning and issues with valving working fast enough to dampen reversals well. In an unlinked Commando one would also loose some the mechanical swing arm support of shocks on either side of axle. Its similar to Ms Peel's 3rd driven wheel turn resister and trailer snow tread adaptor.
 
You could possibly still fashion a rising rate linkage, but the bridge point is rather high up, so design constraints might be too limiting...

Personally, I like 'em!

Conversion to monoshock
 
You'd be better off making a new frame, or modifying a modern one to take the commando motor. Getting the chain line and the steering head angle correct as you raise the rear end is difficult, if you are modifying an old frame. You'd need to increase the suspension travel on the forks as well or the handling could be suspect. How about a Ducati Monster frame ?
 
acotrel said:
You'd be better off making a new frame, or modifying a modern one to take the commando motor. Getting the chain line and the steering head angle correct as you raise the rear end is difficult, if you are modifying an old frame. You'd need to increase the suspension travel on the forks as well or the handling could be suspect. How about a Ducati Monster frame ?
Click to expand...
Ducati Monster frame is a great idea.
Shame to detune with an obsolete old pushrod parallel twin though!
How about a Ducati Monster engine...
 
A Norcati? What a concept. Norcati, I like the sound of that.
I don't think I am deviating too for from topic for we are discussing bastardizations here.

My history has been, if I can't have one then I settle for the other. However, combining these two seems mechanically unsettling, being so pure within themselves.
Norcati, it feels good on the tongue.

Sorry for the brain fart.

I just googled "Norcati" and it is not all that uncommon.
 
Pete,

Even more common is a Tricati using a Triumph unit 350 or 500 twin in a ducati single frame.
 
dave M said:
Pete,

Even more common is a Tricati using a Triumph unit 350 or 500 twin in a ducati single frame.
Click to expand...
Ya, I didn't see any Norton motors in these scenarios.
 
Well consider the time effort and cost involved to produce a system that has no advantages over the original system and probably more than a few disadvantages. If you want something special put a set of Ohlins shocks on the back.
 
A good mono shock (not cantilever) will work very well but you will be making the parts yourself including the swing arm.

These vamped classics seem to be doing OK with twin coil overs.

3:36 8)
[video]http://youtu.be/Jaa6ToWQFfM[/video]
 
I'm thinking of putting together a bobber out of spare parts I have.
I want the hard tail type of look without actually being a hard tail so I was thinking this would possibly be a good starting point.
I understand it won't function better, it's purely for aesthetics
 
lcgtr said:
I want the hard tail type of look without actually being a hard tail
Click to expand...

It would be easier to modify the Commando swing arm but would need a short shock absorber.
 
Mono shock Commando ain't new and obviously works good enough so please see what ya can come up with - especially how to make a top mount for the shock.
 
It's so simple, if you WANT to do it, it doesn't take rocket science.

The frame mods involve 2 simple tabs welded to the underside of the main tube. Only other big deal is finding a second good, late model swingarm, also no biggie.
 
Why do you need another swingarm, surely some fabrication and welding of the top section is all that is needed?
 
I found it very easy to adapt a second swingarm, but certainly you could build your own structure.
 
Duh check your fat tire factor with the chain next to it regardless of swing arm. Its possible to fit 130 next to chain if rim moved away from it some and even bigger meat if ya modify cradle and tranny to shift chain a bit more away from tire. I don't think its possible to fit 130 tire past a mounted fender/tag even if chain would clear. 120 size takes a bit of ram jam puzzling to get mine installed. Unless seeking the mileage or have power enough to ignore the extra mass of 120 i don't consider wider rear an upgrade to seek but does look the big butt business all the rage this decade. If ya gonna mono it why not start from scratch and make SA out of alloy as likely little extra cost/time wise than over all project to prefect.
 
lcgtr said:
this swing arm will allow a wider tyre
Click to expand...

So will the Commando swing arm perhaps to the tune of a 150, the stock rear hub also has a large offset (rim edge to chain) with the option of other wheels.
 
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