What kind of Top Case are you mounting? Does it have an adapter with it?
Over the years I mounted the bags onto various racks etc. The last one I did, I removed the stock rack and bolted the adapter plate in it's place. (using the holes that were intended for the original rack) I used large washers to raise the rear of the trunk so that it set level..
Connie rider is correct. If the "rack" you are referring to is the OEM plastic thingy, it is good for carrying no more than a loaf of bread. If you want to mount a top case or anything else, you'll need to decide what you want, then find out what the manufacturer of the luggage has in the way of a bracket(s). In the case of Givi Monokey boxes, you remove the plastic crap and install an adapter plate (which will vary depending on the motorcycle model), which will bolt in some fashion to the rear subframe, and then the mounting plate for the box, which has the quick release tabs, etc., that actually hold the box. There are other brands and types. There are some people on this forum who have made their own adapters for different type of boxes. Search function will keep you reading for awhile, and I'm sure others will chime in with their ideas.
Look at Murph's site again. It says to install the Rails and then attach the mounting plate to the rails... I assure you, When you buy the bag from Murph you can get everything you need... AND you'll get it quick...
My case came with a mounting platform of sorts. I ended up using some 1" square steel tubing to extend the 'mounting surface' backwards, drilled holes to match up with the holes in the existing plastic rack, and bolted my case to the frame screw holes that the rack attaches to.
Because of my specific situation, I left the plastic rack in place as a spacer of sorts. The mounting hardware came with two lengths of steel, which I used to pinch the tubular steel in between, and placed some eyehook bolts with the loops at the bottom which secure the two strips of steel and thread through the mounting platform, for attaching bungies later.
Then I attached the mounting platform and case to the bike with two bolts extending through to the threaded frame bolt holes using threaded rod cut to length, two bolts that secured the tubular steel to the frame (in the middle), and the eyehook bolts holding the case at the back. Then I used wing nuts to attach the case to the platform I built, so I could remove the case at some point in the future. I also incorporated a quick release plug into the wiring for the lights on the case (expertly stuffed between the seat mount and the rack). Note that I haven't removed the case since...
Unfortunately, the bike has been pushed over/fell/tipped over/skidded multiple times since I mounted this. The case has remained in place and has not budged, despite kissing the pavement somewhat violently several times.
The side cases did not fare as well... I've ended up welding both side case antlers at least once, and one antler is currently broken again... My left case is currently being held together with gaff tape and love...
My case has quite a bit of stuff in it (oil, funnel, tool kit, jumper cables, straps, rags, etc.). When I was hanging with the local sport bike guys, I was the 'fix it' guy, so they liked having me around.
Here's a pic showing the eyehooks and the tubular steel. I wrapped the tubular steel with gaff tape, hence the rough black finish on the tubing.
Two Skies, Hope this isn't a problem for you, but, I noticed your right bag is sagging very much like mine did. After my outside rear brake pad wore out unexpectedly, I found out the bag was actually hitting/ rubbing the tab on the brake caliber (there were scratch marks on the back of the bag). Turns out the rubber mounts inside the bar the antler screws in, up top, had broke loose. I wound up installing a second rubber bumper between the antler and the frame to fix this.
Yeah, at the time I took that pic, the rubber spacer that I use to even up the bags had de-adhered itself and fell off the bike, no doubt while I was riding.
I use some 1 1/2" or so rubber furniture pad discs as spacers (2 per side, one on the antler, one on the surface the antler rests against) to even up my bags. They help absorb the shock of the bags bouncing about among other things, plus two of them pretty much eliminates the play I've observed. Sure, I could bolt them to eliminate movement altogether, but the spacers do a good enough job, until the adhesive fails. I keep extras in my top case for when this happens.
I wish I had seen a Shad case in person before buying it. It's OK. I paid $245. I guess that's the going rate for "name brand" cases but it doesn't look very well built. I like the fact that I have the extra room but if I had to do it over I'd look at other brands or even a used cases.
I just received and installed the Shad case and mounting rails from Murphs. I am quite happy with everything. The quality of the rails (Murphs) is fantastic. The actual top case is good but not super heavy duty. For the price and capacity i am satisfied.
Opening up this thread again with one question. Do the rails from Murph fit any of the Shad 26L and 33L mounting plates? I'm not interested in the 46L, too big for my liking.