I finally got around to completing the lower rail of the Subframe. I originally planned on not creating new lowers however trying to figure out the Compound Angles and Length along with the horrible results seen below I cut them entirely off and made new lowers.






The new lower legs meet the top rails right after the pie cut and welded area. Hopefully the downward stress from the leverage of the seat and a passenger on the rear part of the subframe will get transmitted into this leg then into the main fame spar.







My girl friend and I got onto the bike and bounced around a bit, there was absolutely no flex what so ever.



I still need to add a brace between the upper rails mounting right where the lower meets the upper, hopefully providing more strength. I also have some small metal triangles I cut out of some plate and will use them as gussets adding one to each side of the middle cross brace (4) as well as 2 for the rear brace. I plan on drilling out the centers of these triangles and welding a nut over the hole on the top side so the nut isn't visible from the rear. This will provide me with future mounting spots if the need arises. I still need to "dress" the welds a touch more, clean some spatter off but overall it came out halfway decent IMHO.The pictures are deceiving as it appears the right rail is crooked, when lying a level across the upper rails in various spots there dead on level. The seat when mounted sits perfectly flush and level as well.



Speaking of th seat (Ducati Monster) heres how I mounted it. The underside front portion of the seats plastic base has two 1" wide forks which are meant to slide under a bracket to secure the front.



I saved the bracket that originally mounted the stock seat locking mechanism and just trimmed and welded it right behind the gas tank allowing the plastic forks of the seat to tightly slide under securing the front portion of the seat.



On each side of the rear portion of the seat there are 2 threaded boss's to bolt the rear portion of the seat down. I don't plan on using a seat lock mechanism and am aware of the hazards of such like theft but rather wanted a tool less way to mount and more importantly remove the seat especially if broken down and needing access to the battery (Which by the way was relocated forward in the space above the shocks top mount) or other electronics.

So I want to Lowes and browsed around the hardware dept. for something that would work. First I found some 1/4"W x 2"L clevis pins and the hairpins/cotter keys that go with them. Next I found some 1/4" rubber grommets. The clevis pins had a portion where no holes were drilled through along with a flared head, I figured I could cut the head off, and tap a set of threads down this portion allowing me to screw it into the rearward seat boss's having a set of fixed studs in the seat.



With this in mind all I had to do was cut and bend 2 L brackets to the appropriate size, weld them to the subframe top rails, drill 2 holes in the tops of these L bracket to match the holes/studs in the seat, and insert the grommets for the studs to go through.



Next I applied blue loctite to the clevis studs and secured them into the seat base.



When inserting the studs into the bracket I put a 1/4"washer on each side of the grommet which created a slight interference fit when inserting the hairpins through the studs, locking down the rear portion of the seat. The rubber grommets also help make it a snug fit and may reduce any vibrations transmitted from the frame to the seat.





This set up does not protrude from the sides of the seat and won't get caught up on the passengers leg lessing the chance of the hairpins accidentally being pulled out.





The seat has absolutely no play in it now and can be removed painlessly without tools.

Heres the final shot of the day.

hot stuff.

That looks really good!  Out of curiousity, what are you going to do about the portion of the subframe visible from the side?

If your talking about the triangle portion created by the upper , lower and main frame spar I plan to inset from the back some rubber coated industrial speaker grill cut to fit that can be seen laying up against the dirt bikes front tire thats sitting in the back ground in the first picture in this thread.

If your talking about the sub frame upper rail that the seat rests on and is noticeably visible from the side, I don't quite no yet, any ideas.

Using the same speaker grill I thought about perhaps making a surround type of piece that is shaped like a Horseshoe with the open ends flanking the upper rails at the front of the seat with the rounded portion of the horseshoe shape form fitting to the curve and area under the seats rear position. This would create a type of skirt for that portion of the rail? To make it a tad sleeker I could perhaps Roll this speaker grill so when viewed from the side the grill has a round shape to it, tucking inwards and under the visible rail?

Realistically I have no idea, I may just leave it be and hope the Flat Black paint makes it a tad less visible once painted, who knows though.

What I really need to do is figure out how to make a removable, invisible, rotating, spring loaded, passenger foot peg mount set up.

Thanks for the kind words.

Looks so good dude , Amazing work 

I was talking about the upper rail the seat rests on.  I'm not quite sure that the speaker mesh would quite have the effect your thinking, but I might be imaging something else.  You can only try and find out!  If you can find a way to cover/hide that, this would be in my top 3 favorite mods!  Keep up the good work and keep us posted!