Paugho 45 build

[nifty]

The brake arm can act in tension from below the axle, or in compression from above the axle. Since the rear axle is fixed (no suspension travel), even allowing the caliper or bracket to rotate until it contacts the frame. The length and position of the link do not matter as long as the caliper can be bled. The link for a swing arm should be floated at both ends to transfer braking load back into the chassis, rather than loading the suspension.
If in compression, the attachment must be stiff enough to prevent bending; in tension even a 5/16" rod is enough.
Any lateral misalignment (link not parallel to the wheelbase) should be cured with shims (rather than a Heim joint).

Kitabel, with all due respect.
His rear brake anchor tab is on lower tube of rigid frame, hence without welding, he needs a tension brake stay.
On most Harleys, but especially on a rigid frame, a floating rear brake support with parallel link does absolutely nothing, except create unnecessary work and more things to go wrong.
It is my humble opinion that, only those with a death wish would use a 5/16" tension rod on a rear brake, floating or not.
I don't doubt that a 5/16" rod material could be found that, on paper, exceeds the tension force induced by the caliper. But when you cut a thread on it, weld some eyes to its ends, or whatever to make it actually work as a brake stay, all your calculations go out the window.
No production motorcycle uses anything close to a 5/16" rod for a brake stay, they all use similar to above Willwood pic, its called added safety factor.
Sure, the brave and knowledgeable could thin it down a bit, at their own risk...
The poster Nanonevol appears to be an ordinary guy, building a motorcycle, to me, what you suggest Kitabel, is downright dangerous and potentially lethal.

Nifty

[nanonevol]

Ok, I think I get it now. V twin sells a bracket of the pictured Wilwood type.
I see other setups like this but they are not so common.
I’ll likely use a piece of flat steel for the stay.
Paugho, by the way only say they don’t offer anything but say to look aftermarket.
Thank you all for helping me sort this out. All new to me.

[kitabel]

You found fault with something I did not say.

[animal12]

Is a piece of flat steel going to be strong enough , or should it have a angle running or some kind of strength added the length to keep it from
collapsing ?
animal

[nanonevol]

Is a piece of flat steel going to be strong enough , or should it have a angle running or some kind of strength added the length to keep it from
collapsing ?
animal

That seems to be what is used as in the above pictured Wilwood.
I’ll take it easy at first.

[animal12]

First motorcycle as a kid was missing the stay . I made one from a piece of flat bar I found in the garage . First time I hit the back brake I was over the bars & after I picked myself up I had to pry my homemade bar from the spokes in the back wheel . Fortunately I was making my test run in the orchard across from my folk's house & had some nice hard dirt to land on .
animal

[kitabel]

Not sure?
Read my post v e r y c a r e f u l l y.

The 2 directional loads are exact opposites. When used in tension, even a length of wire braid is more than enough.

More thoughts in my article here: http://victorylibrary.com/brit/2LS.htm

[nanonevol]

I understand a floating disc but not the above mentioned floating parallel link or stay (despite much searching).
Maybe someone could draw me a picture.
Not that I plan to need one with my rigid frame, just curious what the controversy is about.

[nifty]

Floating discs, floating calipers and floating caliper supports, are 3 different animals.

Floating rear caliper support is only of any use with rear suspension (one can also float rear drum brake backing plate & shoes)
H-D springers, old & modernish, use floating front brakes, anchored via link to rear leg, for same reason, i.e. applying springer brake has little effect on fork action.

Floating rear brake support usually has bushing, or bearing to axle spacer, as suspension moves, rear brake "floats" on axle spacer.
Parallel link often in tension and usually more substantial than a strand of wire, or 5/16" rod, parallel link usually has rose/heim joints, or some kind of bearing at each end, so as suspension moves, everything floats freely and nicely.
Front of usually longer parallel link (tension or compression) anchors to frame, instead of swing arm.
Braking induced reaction forces fed into frame, not rear suspension.
Rear suspension free to work simultaneously with seriously applying rear brake
Concept intended to reduce/eliminate rear wheel brake hop & lock-up when front brake also seriously applied and rear of bike lightens up
Invented for motorcycle racing, can go deeper into corners, harder under brakes, before loss of control.
All of which is why IMO you do not want it on your 45" project

Above description is simplified, the science of racing suspension is a very deep subject and is constantly changing.

Here's a modern bicycle with a floating rear disc brake support, with compression parallel link.
Hoping I have helped your understanding, and hoping your project gets back on topic.

Nifty

floating caliper support, compression parallel link.jpg (119.71 KiB) Viewed 749 times

[RooDog]

Funny thing is that most any automotive rear brakes are anchored securely to the axle housing. The only reason I see for an anchoring link on a Harley's rear suspension is to allow the caliper to move when adjusting the rear chain/belt drive. Also to direct the braking forces closer to the pivot point at the front of that swingarm to negate bending moments to said arm
And opposing piston calipers, either 2 or 4 piston, negate the need for lateral floating disc or calipers & brackets. as the opposing pistons are self centering, not so with a single piston caliper which are cheaper to manufacture with fewer parts. Some "floating" two piece rotors are done that way to allow for radial thermal expansion. Just some more turds to throw in to this soup we are brewing here.
But maybe the KISS method can be applied here, Keep It Simple Stupid. After all it is a rigid frame with no torque reactions to speak of.
....RooDog...

[nifty]

But maybe the KISS method can be applied here, Keep It Simple Stupid. After all it is a rigid frame with no torque reactions to speak of.
....RooDog...

Amen to that
Nifty

[nanonevol]

Agreed, but thanks fellas, I learned a lot.

[kitabel]

Only reason not to float the torque link (permit rotation at both ends) in vehicles with rear suspension (bikes, cars, airplanes):
CHEAPER

Rigid frames have no chassis torque? Stop the rear wheel on a dyno; watch what happens.

[RooDog]

Most of us don't have a dyno handy...

[kitabel]

have a nice day