Thread: ORGS build up
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Old 05-12-2012, 11:24 AM   #158
x3300 OP
geoff
 
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
New Seat Pan

The old seat pan I had made no longer works with the new subframe, plus I was not entirely satisfied with the way the old one turned out, so I decided to make up a new one. I started with a model made from thin cardboard that I thought looked good on the bike, and then transfered that pattern to some 3/32" aluminum sheet I had been saving.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/layout.jpg

I used a squaring shear to trim out the blank.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/blank.jpg

And used this sheet metal brake to bend the sides to the angle I had decided on with the cardboard model. To get the large radius bend from the brake I set the brake fingers back about 20 mm from the hinge joint, the setup of which can just be seen in this view.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/brake.jpg

Here's the formed pan compared to my cardboard model. I rounded down the sharp corners with a file.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/bent.jpg

To space the pan from the frame and to add some stiffness I cut these sections from aluminum rectangle stock. As can be seen, in preparation for welding I cleaned up the area around the stiffeners with a flapper disk on an electric angle grinder.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/stifeners.jpg

I had planned to make a slip-in front mount to make it easy to access under the seat, but decided for now to simplify the mount and just have it bolt together. I'll add the slip-in mount when I make an under seat storage box. For the frame side of the mount I attached this section of aluminum angle stock to the rear seat mount and drilled a single hole in its top.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/front-frame-mount.jpg

I found I needed to do some rework on the pan's front mount once I got it fitted on the bike. It was too wide to fit within the subframe mounting bolts. With the pan centered on the bike I drilled up through the hole in the frame mount and into the pan mount and pan.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/front-mount.jpg

To hold the blind side of the front mount bolt which will be covered by the seat foam and cover I welded a tab to the head of a bolt and fixed the tab to the pan with a pop rivet. I ground the bolt head down to a lower profile.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/front-bolt.jpg

For the rear mount I made these tabs to weld to the subframe.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/frame-tabs.jpg

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/tabs-welded.jpg

On the seat pan I welded two tabs cut from 1" x 1/8" aluminum stock.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/pan-tabs.jpg

I used these clip-on nuts for the rear mount bolts. I may weld some nuts on the bottom of the frame tabs the next time I have the subframe off, or better, make a locking quick release mechanism to work with the slip-in front mount.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/rear-bolts.jpg

Here's the seat pan ready for foam and a cover. The side panels really aren't necessary, but I didn't want to just have square block of a seat there so I put on some sides with angles that looked interesting when viewed together with the tank and subframe.

http://stuff.gotdns.org/bike/orgs-build-up/44-new-seat-pan/pan-done.jpg

-x3300
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