[axman88]

Ok, so the rack is done.  I am already not 100% pleased.  The rack itself has flex, and the pillion frame flexes a bit, so overall the flexing might become an issue down the road.

I already think I have a solution, but I have other projects around the home thst are more pressing.  Anyway, I made a video of all the pictures using imovie, on my ipad.  A little hokie, but what the heck, it was fun.

https://youtu.be/7EUWf6JhGIo?si=0TlZL9dF8FYnsiG1

I've definitely experienced problems with flex on motorcycle racks before.  The problem with flexing, is that those are reversing cyclical loads, and that is what causes fatigue failure.  To resist fatigue, structures need to be many times stronger than they would for static loading.

Your cantilever design unfortunately adds a diving board onto the end of a diving board.  Wherever possible, it's good to "triangulate" support.  Three points of support, spaced means the load at any one of them is radically reduced.  Imagining connecting points as pins which don't resist rotation, like loose bolts, and designing a structure which seems stable under those conditions, will put you on the right path to making a durable structure.

On my C5, I went with the simply open "L" pannier frames on either side.  These have three mounting points, widely spaced, including a simple clamp around the "arced" fender frames.  https://accessories.hitchcocksmotorcycles.com/accessory-shop/C5-Classic-Canvas-Panniers/40493   Hitchcocks is out of stock, but I think the style is still available on Ebay.

Perhaps you could add struts to your existing build, that would tie it to those rear fender frames.  That would do a lot towards taming the flex.  Eliminating the flexing means taming the potential for fatique failure.

[Handirifle]

Diving board on the end of a diving board, lol.  Good description.  Sadly I didn't see the seat frame being as flexible as it is, but adding 15" of lever to it surely didn't help.

You guys seem to feel the fender supports would handle the load, but later the pannier racks will be supported in the same way, and I am not sold that it would handle both.  I think a possible redesign is in order.

Usually I foresee these kind of issues before they take physical form, but not this time.  I am still leaning towards a one bolt design for seat removal and top box rack attachment.  There is a flat bar across the center of the pillion frame where currently I have two bolts into the seat pan, and a third bolt in the rear clamping the seat pan to it.  I need to figure a way to put either forward facing hooks into those holes, or make them into keyholes that I can slide the front of the seat, and or the pillion frame into and still utilize the clamp at the rear.  Kinda leaning towards the keyhole.  I just need to come up with the correct size parts to slip into the keyhole.

But as I said before, I am going to push the existing location of the top box forward another 3 inches on the rack and see if that helps. 

[om15]

My Bullet has the twin seat and therefore I can't fit a rack easily. I overcame the problem by modifying a Hitchcocks tail bag that I had fitted to my Himalayan, I used the two bolt holes in the seat, the bolt hole on the mudguard stay and used a P clip fitted to the frame, it is a firm attachment and takes a "get you home" kit, I have a few spanners, tye wraps, a foam aerosol to fix punctures and some tape. Looks ok, it is out of the way and does the job.

[Handirifle]

Yea I am not a fan of split seats like mine has, BUT, it will end up being a blessing for my needs.
Nice job on the bag adaptation.

[AzCal Retred]

Oddly enough wood (the original composite) has incredible cyclical fatigue resistance. It also dampens vibration a bit. Might be a useful option for support struts. Varnished wood is rather "yachty ($$$)" also. 

[Handirifle]

Well good news, my panniers arrived about 2 weeks earlier than expected.  Bad news is It will still be about 2 weeks before I can work on the bike again.

These bags are really nice, as is the top box.  The quality seems as food as many name brands I have seen.  With $313 delivered, for the pair, and under $200 for the top box, its a lot less than I could have spent.  I could have spent less, for sure, but if the C5 ever gets sold, the luggage will not go with the bike. 

I got used to a lot of storage with my Harley, so this will make the transition, when I have to sell the Harley down the road, they will go on its replacement.

[Handirifle]

Have not had time to start on the pannier racks, but did do the redesign on the rear seat mount.  Previously I had to remove the rear seat frame and undo the bolts from underneath.  That was not going to cut it, especially when I want to EASILY be able to swap the seat for the top box mount.

This is a two step process.  The first step is to make the seat quick detach, WITHOUT removing the pillion frame to do it.  Mission accomplished.  No pics just yet, am trying to video it, so it males sense, plus I probably need to redo the video.

Basically I made a tongue that goes under the cross bracket of the rear seat frame.  The tongue is riveted to the seat bottom.  Then to lock it in, I made a U shaped bracket with the ends beside each of the threaded 6mm holes in the pannier frame.  This bracket is also riveted to the seat bottom.  All are 5mm rivets.  So to put the seat on, I set it on the frame, slide it forward, and align the two 6mm bolts on the sides and tighten the 6mm bolts.  To remove the seat, remove the two bolts on the sides, and pull backwards amd lift.  One bracket is 1/8" steel, the other is 12ga steel.

As mentioned, once I make a decent video I will post a link.  It will be a lot easier to understand.  The rear, larger holes on the back sides of the frame will be used for the pannier frames to mount.

Tomorrow, I hope to figure out how to mount the top box bracket to the rear seat frame, in a quick fashion as well, but also one that keeps it from being easily stolen.  Mostly I want the mounting bolts only accessible when the box is removed.

[Handirifle]

Ok, so with the help of folks here and trial and error, I now have a rock solid convertible setup, to easily switch from rear top box to pillion seat.

Its all shown here in my latest youtube post.
https://youtu.be/hl-qScCnw2k?si=4sWMW6Pp14CiiXh0

There is ZERO wiggle or flex in this setup.   Here is a pic of it, but you will see in the video how it works.

[Handirifle]

My next project for this bike, will be for the pannier racks.  Am excited to get this step done and grt onto the next phase,

[om15]

Nice set up handirifle, out of interest what tyres have you got fitted?

[Handirifle]

Well I was going to start on my pannier racks today, since its raining, but decided to wait and get some 3/4" tubing for the main section.  Don't want to go thru what happened on my first attempt on the top box rack, and have it too flexible.

[Handirifle]

Nice set up handirifle, out of interest what tyres have you got fitted?

Nothing special, Shinko Golden Boy's.  Spared no expense, lol.

[om15]

My tyres are the original Avons, same age as the bikes, so am booked in for a new set of tyres next week, after a lot of browsing I have chosen Dunlop K70s, middle price range, good reviews and much more tread than the Avons.

[Handirifle]

When I was gifted this bike it still had its OEM tires on it, from 2011.  They looked new, except for all the sidewall cracks.  I put about 10 miles on them just to get to know the bike, but couldn't trust them past that.  I live on a dirt road, and there are lots of them around, thus the knobbies.  Compared to my Harley, this is my "lightweight" scrambler, lol.

[Handirifle]

Made some more progress today.  I have the rectangular sections done.  That was the hardest part (I think so anyway) and now I just need to make and weld on the pieces to bolt it to the frame. 

Here's a short video to show the progress.  I think its edited better than my others, hopefully yo make it a little less boring, lol.

I decided, at the last minute, to use the 3/4" EMT.  The supports will be 5/8".

https://youtu.be/cTdwJTc2NdA?si=GhYeJRzLR-VnJR9K