Matching Top Case

Both Comfort and convenience

Although it would be unlikely that we would use this motorcycle for its intended purpose of traveling around the globe with panniers and top case stuffed full of all the essential items needed to live for months/years on the road, we knew that we would need one piece of luggage for our everyday use. That convenience would be the top case. Not only would it provide a place for carrying groceries and other supplies back to the truck from town shops, but it also provided a comfortable backrest for Wendy to rest against when riding. It would also keep her from sliding off the back of the bike when I did wheelies while racing away from stop lights… ya, like that would ever happen.

Although we could have bought a smaller top case that would provide the needed backrest, we wanted a case that was large enough to store both of our full face helmets so they could be locked away out of sight. This was particularly important when using the bike to visit a town that was too congested for us to enter with the big truck. If we wanted to park the bike and snoop around for a few hours, we wouldn’t have to carry the helmets with us while doing so.

Although we looked at a lot of aftermarket top cases that might have done the job, it was our good fortune that BMW made a large top case for several of their other road touring bikes, and with a little work, it could be adapted to fit our GS Adventure (GSA). What turned out to be the icing on the cake was the fact that one of those other road touring bikes was produced in the exact same colour as our new GSA. So by ordering the top case for that bike, it would match our paint scheme exactly. There would be no need for us to try and get a body shop to match our bike’s paint, and repaint the case.

It was expensive compared to the after market double helmet sized cases, but it was the right colour and shape, had a nice padded backrest on it, came with a rear high height tail and brake light, and was able to be keyed to match the ignition key for our bike. It also had a custom fitted luggage bag that would allow us to take a few things with us if we wanted to stay overnight somewhere away from the truck.

Part of what made this top case so expensive compared to others was the sophistication of it’s design, and the quality of its build. Molded from glass reinforced plastic with a dual wall construction, the case is nicely carpeted inside, the lid has gas struts to hold it open, there’s a dome light inside for convenience at night, and most importantly it has a four point internal latching system for security. No one is getting inside this case short of taking a reciprocating saw to it and cutting it completely in half.

What sets this case apart, however, is its ability to be removed from the bike with the simple twist of a hidden dial inside the case. One simply has to unplug the electrical cable from under the rear seat, twist the dial, and the case lifts off the rear rack. It even has little feet so the case can be placed on the ground without the worry of scuffing up the outside finish. Perfect!

But Here’s the rub

This case was made to fit the BMW R1250 RT, and the K1600 GT/GTL. They both have a completely different rear carrier than our R1250 GSA. So their top case won’t just clip into our rack. But fortunately for us, the fit is close. All we had to do is a little modification to our stainless steel rear rack, and it would work.

The most difficult challenge to overcome was the mental one. The thought of attacking our shiny new stainless steel luggage carrier with an angle grinder and zip disk was daunting. After all, once cut, the rack was no longer of any use for securing the factory aluminum top case that was meant to be used with this bike, the replacement cost of which is over $450.

With Gritted Teeth…

So after much consideration, and numerous cups of coffee to jack up my energy, I grabbed my well used angle grinder and had at it. Originally I was going to remove only a portion of the carrier centre, and try and use some of what remained to hold the new box. But not long into the first cuts, I could see that my original idea was simply not going to work. The front to back clamping points on the top case were just too far apart. To make things worse, by cutting away the major portion of the centre part, the carrier would lose most of its rigidity. You see, that centre section had three dimensional shape to it, and that gave the outer tubular frame all of its resistance to torsional deflection. By leaving the little that remained, it was only two dimensional, and would therefore flex, especially with a large top case that could apply considerable leverage. So we needed to resort to Plan B.

After a good deal more measuring, it was determined that the entire centre portion of the carrier would need to go. Then in its place, a new piece of tubing that’s the same size as the carrier tube, could be welded in place. By using tubing, the lost three dimensional rigidity would be replaced. The first step would be to curve the new tubing so it would mate with the grippers on the underside of the case, and also provide some vertical lift to the cross piece so the shape on the underside of the case would sit right. Since we didn’t have any of the tube bending machinery that we had in our manufacturing business, we had to curve the tubing using the old school method. You might be thinking that the tubing looks awfully long for what we need, but when working like this you need extra on each end to manipulate the shape, and then the extra is cut off.

With the curve formed and the excess material cut off, the two ends were coped to perfectly fit the radius of the carrier tube and the corner bend where the welds would be made. The carrier was then screwed to the wood bench with the precise dimensions taken from the motorcycle mounting points. After that it was just a matter of positioning the new cross member and welding it into place. Once the welds were cleaned up it would look like it was originally made that way.

The final thing we had to do was to weld two flat bar gussets in the rear corners for the locking dogs under the top case to clip into when the attachment dial inside the case was turned. With that done, and a bit of wiring to hook the case into the electrical system for the bike, the project was all finished.