Before my trip on the COBDR and IDBDR this past September, I knew I needed a decent skidplate. I'm a pretty big procrastinator and I'm pretty cheap, so that combo left me without a lot of options a few days before my trip. Nothing I found online was looking like it would be beefy enough for me, and nothing was up in the used market. I had been planning this build for a while, so I had the process in mind, and luckily it worked out. Anyone who has seen my winter projects thread knows I have had this on the list for a couple winters. Well, three days before my trip I finally started on it.
I have Givi crash bars, so the front mount was obvious. My first step for me was to find a place to mount the rear. I looked around and I know that most skidplates attach to the center stand mount but the brackets required to make that work seemed overly complicated and possibly a bit weak. I found that the side stand mounting bolt was nice and beefy, and there was an exhaust mounting point almost directly across from it. I measured, bent and drilled a piece of flat bar to span across.
I missed a pic of the sidestand side, but the mount rests on the inside near the bolt head. Both of the bolts had enough length that I didn't have to find longer replacements.
My plan was to take one large piece of scrap aluminum plate to make the entire thing, get a shape, cut it out flat, and bend the plate. So I set to work on making a template out of cardboard. I cut out a large rectangle for the base, and several smaller pieces to help hold the shape of the bends. I vice gripped the back of the rectangle to the rear mount, and made bends where I wanted the bend points, then used the mounting bolts for the front to hold it in place while I taped the other pieces to keep my angles. This was a painful step, but it really helped in the end.
Next I cut out pieces for the sides, so I could get the angles of the cuts right, and see where I wanted all my bends, and check for interference.
Once I got the cardboard template where I was happy with it, I flattened it out and transferred the shape to my aluminum plate.
I cut the plate with my circular saw, and also scored the plate at the bend lines using shallow depth cuts. This was important to get straight bends without a brake, and also turned out to be important just to get the plate bent at all. I also cleaned all the old paint off the bend an cut lines so it would be clean for welding later.
I also made a couple extra cuts on scraps so that I could test the bends and use it for some warmup welds.
I clamped the plate to the bike and started bending the bottom section. I used some scrap bits taped between the plate and the exhaust to help maintain the distance from the exhaust.
I drilled holes for the mounting brackets before I started bending the sides. On the rear I used countersunk flat heads so I didn't have anything to snag on rocks or whatever I come across.
Bending the sides was no small feat. I used a six foot piece of 2" square structural steel I had, plus my weight, plus the weight of the bike and a jack. This step I would do differently next time, but I still can't think of a better way.
I didn't get any pics of the bending, but here it is bent up:
I drilled a hole for the oil drain plug, and a the hole on the rear left is a clearance hole for the exhaust clamp that sits there.
I also drilled some holes for the oil cooler, this came out pretty cool.
Then I got to welding. I don't have a ton of aluminum welding experience, and it took me quite a while to get test welds I was happy with. And happy with wasn't exactly great, but simply strong enough, and not pretty. I was completely out of time, already a day late leaving, so I rounded out the corners and left the shape the way it was. I might shape it another time.
Here it is mounted on the bike, and how it stood for the entire month long trip. I left it unpainted. It took a few good knocks and scrapes but nothing cracked or broke. I used bicycle tube wrapped around the crash bars, but I didn't make any vibration dampenning for the rear mount. When I mounted it up, the clearance on the front was a little tight so over 7k rpm I can hear the exhaust hitting the plate, I'll make some adjustments over the winter, but it lasted 11,000 km including plenty of off road like this.
In the end I was happy with the build considering the time I had. I spent about two half days and one day that had a wedding in the afternoon/evening. If I were to do it again, I would prep the welding areas more, practice welding on more scrap, and modify the rear mount slightly. The rear mount has a spot where it sticks out a bit too far, it bends at a 90 where the plate bends at 45. You can see it in the last picture. That point still held up well, and I didn't snag it like I thought might happen, but it could be better.
I don't know if vibration dampening on the rear would help with anything, but I might play with that a bit.