1981 XS650 Project Something or other (going cafe-ish)

Re: 1981 XS650 Project Something or other

Got the front mounts for the bellcrank tacked together. Did a quick mock up with the bellcrank, there will be bracing for the mounts so don't freak.
Next I'll work on the rear shock mount and the swing arm brace/pushrod mount.

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Re: 1981 XS650 Project Something or other

Looks interesting!

Nice to see another xs!
 
Re: 1981 XS650 Project Something or other

so where does the shock go ? how much wheel travel are you designing for ?
 
Re: 1981 XS650 Project Something or other

Yeah, would be interesting to see you draw some lines with paint or something to show the geometry. I thought before you would have mounted the triangle different to have the shock between the backbone and the crank, with how it's zip tied up now it looks like you'd have the shock pointing back?
 
Re: 1981 XS650 Project Something or other

I'm shooting for 3.5-4 inches of rear wheel travel. Yes, the shock will be under the seat pointing to the rear. Finishing up the mock up tonight, I'll post some pics in the next couple of days
 
Re: 1981 XS650 Project Something or other

Hope everyone enjoyed their weekend, in between yard work and enjoying the sunshine I was able to get a little time in the garage. Sunday I worked on the forward braces for the bellcrank mount. Took 2 pieces of 1" .120 wall tubing, coped one end and cut the other at an angle, welded the angled end to a 1/4" bracket that will be bolted to a clevis that's been welded to the frame.

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That chihuahua turd looking weld is actually 3 or 4 passes, I want that area to be very strong so I probably went a bit overboard

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Re: 1981 XS650 Project Something or other

Did some work on the swingarm this weekend. Originally I was going to fabricate a brace and a mount for the pushrod but I decided to use the brace off of a XT400 swingarm that I had laying around. The brace is almost a perfect fit and has a mount for the pushrod already attached, win win. I'll add some bracing and some plate to the outside rear corners and Bob's your uncle.

Forgot to take a pic of the XT swingarm before I cut it



Cut off

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Cut the front brace out of some 1x2 stock and welded it in

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Re: 1981 XS650 Project Something or other

so a total redesign ?
i don't see any relationship to the pushrod lashup and this braced swinger ???
 
Re: 1981 XS650 Project Something or other

Ideally the brace between the pushrod mount would extend to the actual swing tube, and not the gusset. The gusset isn't very structural in that direction and will probably bend.
 
Re: 1981 XS650 Project Something or other

mathil said:
Ideally the brace between the pushrod mount would extend to the actual swing tube, and not the gusset. The gusset isn't very structural in that direction and will probably bend.
Click to expand...
well a vertical link wont work with that configuration at all anyway, it needs to be a much more horizontal load thus my confusion
 
Re: 1981 XS650 Project Something or other

xb33bsa said:
well a vertical link wont work with that configuration at all anyway, it needs to be a much more horizontal load thus my confusion
Click to expand...

Color me confused, if the gusset isn't structural then why is it even there?? I have no problem moving the brace but I guess I don't see the need. Please enlighten me.

There will be additional bracing as well, that's not going to be the only point of contact between the brace and swingarm
 
Re: 1981 XS650 Project Something or other

xb33bsa said:
so a total redesign ?
i don't see any relationship to the pushrod lashup and this braced swinger ???
Click to expand...

Not a total re-design. Stay with me xb I'll do a complete mock up soon then we can discuss ;)
 
Re: 1981 XS650 Project Something or other

with the attachment point in that new location it wont allow enough movement of a link rod if the link-rod comes straight up
it wasn't going to work in the original configuration either
 
Re: 1981 XS650 Project Something or other

O ye of little faith, it actually works very well. Stay tuned
 
Re: 1981 XS650 Project Something or other

my point being with a vertical link rod with the swinger you now have the angle of moment is way out of the usable range
if you put a link rod on it much closer to 90 degrees the angle of moment it will work
 
Re: 1981 XS650 Project Something or other

billyp said:
Color me confused, if the gusset isn't structural then why is it even there?? I have no problem moving the brace but I guess I don't see the need. Please enlighten me.

There will be additional bracing as well, that's not going to be the only point of contact between the brace and swingarm
Click to expand...

The gusset is designed to keep the tubes from spreading and twisting. If you look at the forces it's designed to resist, a downward force between the tubes isn't one. Imagine a 4" square 1/8" plate, only supported on the perimeter. Then take a hammer and pound on the middle of the plate. I bet you could dent/bend it, and that's how your brace is pushing on the plate.

If you took the same plate, set it on edge and welded a tube on it and then put force on the tube the plate wouldn't bend, but the tube would right where the plate ended. That's the type of force the gusset is meant to resist.

Different shapes are strong one way and weak another. The gusset was designed to be strong horizontally, but it's not strong vertically.

I mean, it could work, and might not fail, but it's not ideal.
 
Re: 1981 XS650 Project Something or other

Can't comment on the linkage without seeing it. Set it up and snap a pic!
 
Re: 1981 XS650 Project Something or other

I completely agree and that's what I'm shooting for. When everything is in place the pushrod will be very close to 90 in relation to the attachment point for the rod on the bellcrank, the pushrod doesn't necessarily have to be mounted horizontal, it all depends on the relationship to the pivot/attachment point and the orientation of the bellcrank. A close to 90 degrees is desirable at both the pushrod and shock attachment points in relation to the bellcrank arms. But you already know all of this I'm sure ;D
 
Re: 1981 XS650 Project Something or other

mathil said:
The gusset is designed to keep the tubes from spreading and twisting. If you look at the forces it's designed to resist, a downward force between the tubes isn't one. Imagine a 4" square 1/8" plate, only supported on the perimeter. Then take a hammer and pound on the middle of the plate. I bet you could dent/bend it, and that's how your brace is pushing on the plate.

If you took the same plate, set it on edge and welded a tube on it and then put force on the tube the plate wouldn't bend, but the tube would right where the plate ended. That's the type of force the gusset is meant to resist.

Different shapes are strong one way and weak another. The gusset was designed to be strong horizontally, but it's not strong vertically.

I mean, it could work, and might not fail, but it's not ideal.
Click to expand...

That's the kind of responses I love, ones that actually give you answers. That all makes total sense mathil, thanks, changes will be made
 
Re: 1981 XS650 Project Something or other

I guess a classic example of how things are strong one way and not another is an egg. Crush it sideways it's easy, crush it lengthwise it's hard.

It's also easy to snap a pencil sideways, but breaking it by pushing down on the end is almost impossible.
 
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