Well sports fans, it is time for another chapter in the saga of
Gretel - my 1983 BMW R100RS (cue the Wagnerian
sturm und drang musik here). As the COVID19 sh!tstorm subsides, I am planning a couple of bike trips hither and yon and so I wanted to try to get a top box mounted on Gretel’s ample derrière in which to tote my stuff (chiefly rain gear etc.).
Several years ago, I found a top box off a Honda <I think> GL1200 Gold Wing at a bike wrecking yard for stupid-cheap money and so I bought it. Frankly, I’m not even sure that I knew why I bought it at the time, but it only cost about $25 and except for some slightly faded pinstriping, it looked solid and the nice chrome latches were secure, even though there were no keys for the locks. I may have had delusions of mounting it on my XS650, but I have since concluded that this scheme would not have been a good idea.
Then along came dear Gretel and so I thought, “
hey, she is a big tourer, she has hard cases (the Krausers)
and she’s black, plus she has such a cute little rear luggage rack - why don’t I bust out the ole’ engineering skills and see if I can mount this box on Gretel?
With a couple of possible trips looming this summer and fall, I got down to business. The BMW rear rack is sort of a dumb design as it is quite small and the forward of three cross-bars is not flat - so attaching anything to it is not easy. Anyhow, I fabbed-up a sheet metal reinforcing plate for the inside of the box, drilled some holes in suitable locations to suit the stock chrome Honda brackets and the box was secured to the seat rack - but it could still pivot forward and backward. Obviously, I needed some "pitch" axis support to prevent that pivoting action.
One of my former students is now an executive with a major automotive engineering consulting firm in Detroit and he suggested using 3D printed brackets to prevent rotation and he even offered to print them for me. So, we took some measurements and the next day he popped out two of the slickest looking brackets you’ve ever seen and holy cow, they work great and fit perfectly. He even incorporated four little hex-shaped recesses in the forward bracket to accept M6 nuts and bowed the upper surface on that same bracket to accommodate the curved recess in the forward-underside of the Honda top box.
You will note from the photo below that my inner steel reinforcing place has some hole-drilling errors. I could blame that on the fact that very few of the surfaces of the Honda box are flat and easy to measure (which is quite true) - but the fact is that I am not much of a machinist. It is too bad really, because Craig had powdercoated the plate - prior to the fitting being done.
Oh well.
All I need to do now is touch up the black paint and white pinstripes and remove the Honda emblem and finally, install the 83mm BMW roundel that is on the way from
evilBay onto the rear of the top box lid.
Pete