How is this subframe braced...?

seamax · November 25, 2009, 03:12:57 PM

This is the look I'm going for with my seat and tail. I was told by alot of members here that i woould need to traingulate the subframe somehow to brace the tail an seat but I want to achieve a clean look like the bike below. Anyone have an idea how he did this?

Here's the link for the bike...

http://www.customfighters.com/forums/showpost.php?p=434504&postcount=2

Paulcet · November 25, 2009, 03:39:49 PM

Quote from: Custom Fighters websiteSubframe: one-off. Removable and selfsupporting using push- and pullrods underneath the tank. Hidden from sight. All powdercoated black

Got to be lots of metal under the tank and seat.

O.C.D. · November 25, 2009, 03:41:28 PM

x2. There has to be an upper triangulation under that seat.

tt_four · November 25, 2009, 03:42:41 PM

I'll see if I can find any better pictures, I've seen a couple builds like those. Obviously the normal 2 rail subframe wouldn't hold, but guys usually just weld on a massive aluminum plate, which is plenty to hold the weight of one person. Oh! I think I know where one is! let me go check

tt_four · November 25, 2009, 03:46:28 PM

There you go. The entire thread for that build is here... http://www.customfighters.com/forums/showthread.php?t=10663

That one is slightly braced, but I've seen some with the same idea that didn't have those wedges in. They ended up pulling that one off and haven't put a new one on yet, but still, that's how it's done. The only problem you'll run into, is that the GS frame isn't shaped like the old gsxr frames. The gsxr frames come back to where the seat meets it, so you can just weld on that plate. The gs500 frame curves down, so you'd have to weld the plate on way under the tank, which would give you a lot more leverage to bend it. You might have to just paint the subframe black so it doesn't stick out as bad. You could also try to find some thinner rails for the lower half of the subframe. If there's only one persons weight on the tail you don't need quite the strength as the stock subframe, which is made to hold 2 people, so you could technically put much skinnier rails on the bottom to give it that same look.

Here's a picture of one with the subframe painted black, kinda gives you a similar feel to it because the subframe doesn't stick out like normal...

seamax · November 25, 2009, 07:38:00 PM

DANG..that's a thick plate. Thanks that was very helpful.

Now I have an idea of how to approach this. Mine wouldn't need that much metal since I'm the only rider.

That is definitely a cool build though.

tt_four · November 27, 2009, 08:36:37 AM

If you look at the back you can see it's only half that thick, and they just braced the sides. I'm still not sure about how well it would work on a GS, considering the front seat butts right up against the frame on the gsxr. On the GS you have a foot of subframe under the tank before the seat even hits it. You're definitely going to have to brace it better than that.

sledge · November 27, 2009, 02:16:59 PM

"Removable and selfsupporting using push- and pullrods underneath the tank. Hidden from sight."

Dont confuse rigidity (or flex) with support, in this case they are two seperate things. Regarding support, sounds like he has cantilevered it......... Rather than using a 1 large brace in contraction he has balanced the forces and used a small brace in contraction together with another small brace in tension. In other words he has one support pushing it up and another holding it up.
Rigidity? well thats easy, just make it big and heavy

seamax · November 27, 2009, 03:00:09 PM

Quote from: sledge on November 27, 2009, 02:16:59 PM
"Removable and selfsupporting using push- and pullrods underneath the tank. Hidden from sight."

Dont confuse rigidity (or flex) with support, in this case they are two seperate things. Regarding support, sounds like he has cantilevered it......... Rather than using a 1 large brace in contraction he has balanced the forces and used a small brace in contraction together with another small brace in tension. In other words he has one support pushing it up and another holding it up.
Rigidity? well thats easy, just make it big and heavy

It's hard to see how the push and pull rods work since the seat is almost horizontal to the tank. There is not much of an angle there for any angular support.

tt_four · November 27, 2009, 03:26:10 PM

but with how tall the front of the seat is, there's definitely some space to put a bit of support. We're used to seeing subframes mounting to the frame with 10 inches between the rails, but that's because they're holding 2 people. You could still fit a short subframe under there that's the same angle as the GSs subframe, just shorter. Look how close these subframe rails are to each other. You don't need a whole lot when it's only one person...

sledge · November 27, 2009, 04:25:17 PM

Quote from: seamax on November 27, 2009, 03:00:09 PM
Quote from: sledge on November 27, 2009, 02:16:59 PM
"Removable and selfsupporting using push- and pullrods underneath the tank. Hidden from sight."

Dont confuse rigidity (or flex) with support, in this case they are two seperate things. Regarding support, sounds like he has cantilevered it......... Rather than using a 1 large brace in contraction he has balanced the forces and used a small brace in contraction together with another small brace in tension. In other words he has one support pushing it up and another holding it up.
Rigidity? well thats easy, just make it big and heavy

It's hard to see how the push and pull rods work since the seat is almost horizontal to the tank. There is not much of an angle there for any angular support.

http://en.wikipedia.org/wiki/Cantilever

mister · November 27, 2009, 04:47:00 PM

I wasn't going to mention cantilever but seeing as Sledge posted the Wiki on it, this is fitting...

The Sydney Harbour Bridge...

One of the most frequent question is... how was it built? The Answer... Cantilevers on each side until the arch met in the middle...

But intrinsic to the arch is the Lattice Pattern. It's used to give Support where straight no lattice would bend. Most noticeable on a Hammerhead Tower Crane (some have jib ties which go from an Afram above the operators cabin to about halfway along the jib, leaving the outermost part to be supported only by the lattice design.

To "close together support arms" interwoven with a lattice (think smaller scale Ducatic Frame) would give additional support.

Michael

Chanse · November 27, 2009, 05:43:56 PM

yeah you didnt read it you just looked at the PRETTY PICTURES.... even the page you linked says its a gsxr 1100... witht he following mods... ( cut and pasted straight from the page) BAD FORM PETER PAN...

Suzuki GSX-R1100 L/N 1990/1992 "The Wraith"

Engine: 1127 cc, repainted gloss. With Dynojet stage 3, 2x2 K&N airfilters, full Yoshimura duplex race exhaust - heavily modified (shortened can and adjusted line). Reworked and lengthend wiringloam hidden from sight

Frame: welds smoothend, subframe and redundant brackets removed. Removable plate behind headstock for all wiring to hide from sight. All powdercoated black.
Subframe: one-off. Removable and selfsupporting using push- and pullrods underneath the tank. Hidden from sight. All powdercoated black

Frontfork: USD, with adjested triple trees, all powdercoated black.

Wheels: Suzuki GSX-R1100, powdercoated black, with GSX-R logo's.

Fontbrakes: 6-pistons Tokico's Kawasaki ZX7R with Goodridge brakelines

Swingarm: Suzuki GSX-R1100, powdercoated black

Rearshock: Koni for Honda CBR600RR, fully adjustable

Tank and frontfender: Suzuki GSX-R1100

Seat-unit: Suzuki GSX-R750 K4 with modified seat, one-off undertail, LED-lightunit with integrated indicators

Hugger: Modified Suzuki GSX-R1100

Headlights: Autostyle

Front indicators: LED, positioned on top of radiator

Brake and clutch master cilinders: Ducati 750SS

Instruments: Koso

Handlebars: ABM, with wiring running inside (one-off)

Paint: Three colours with prismaflakes and airbrush

tt_four · November 27, 2009, 10:03:38 PM

Either way that guy must be huge. He clearly lifted that seat a good 2 or 3 inches higher than it originally was.

lopee · November 27, 2009, 10:34:45 PM

There seem to be the lower braces missing off this sweet track gs. this would lead me to believe that could be enough support for one.

http://gstwins.com/photogallery/displayimage.php?album=2&pos=407

Looks like the gussets have been removed as well.

tt_four · November 28, 2009, 09:35:16 AM

You might be ok. The only real difference I see between a street bike and a track bike, is that you spend a lot more time being lazy and sitting on a street bike. When you're on a track bike you spend a lot more time with your weight on your feet, squeezing the tank, and leaning over the front end. When you're riding around on the road you tend to spend more time with your weight planted, and the least amount of your weight on your hands as possible..... not to mention the fact that there are no pot holes and railroad tracks on a race track. You've also gotta factor in that a track bike gets used a couple hours once every few weekends, street bikes usually get used way more than that.

mister · November 28, 2009, 01:37:48 PM

Quote from: tt_four on November 28, 2009, 09:35:16 AM
You've also gotta factor in that a track bike gets used a couple hours once every few weekends, street bikes usually get used way more than that.

And we don't know what happens to the bike between those weekend rides. Good bet the engine is pulled right down. Chain would be changed. Sprocket. All filters etc., etc. Why not a new tail brace as well?

Michael

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How is this subframe braced...?