Top Box Mounting Concerns (loose fit)

[skidmore]

Hello 'Brickers! I need some of your infinite knowledge.....(I will attempt to attach/insert a pic...I'm dealing with a stock rack and box/mounting plate)

I just picked up a top box (the "small" BMW box) with mounting plate. Although I've seen them on bikes and seen them mounted/dismounted many times, I had no intimate knowledge of the finer details/technique. Casual observation told me the mounting plate attaches to the box via the quarter turn fastener in the bottom of the box. Check....no problemo there. Further casual observation told me the mounting plate slides onto the tail section rack. After a little head scratching I discovered the mounting plate will slide onto the rack by tilting the plate so as to fit the top of the plate into the slots on the rack, then lowering the plate so that the bottom it slides into the slots on the rack. Check again.....no problemo as far as I can tell. Corrections welcomed if I am wrong.

My concern is the damn plate has a lot of slop within the rack. Side to side there is a good 1/8" of movement. Front to back there is a good 1/8" as well. That seems like a hella lot of slopping around. And that's just moving the plate around by hand. When the box is fastened to the plate my concern multiplies. I can't imagine how much flopping and slopping there would be with some payload in the box.

Is this much slop typical? The side to side isn't as much of a concern as the front to back slop. Aside from the annoyance from the damn thing rattling around making noise, there is the concern of it coming loose and OFF whilst in transit. Perhaps this is why I read on IBMW.org to loop a piece of small diameter steel cable in case the case decides to go into orbit!?

-skid

[Inge K.]

On the rearside of the plate most of the area should be covered with rubber foam, which makes a tight fit
between the plate and the carrier/fastback.

On the plate you have a square hole, on the topbox you have two pointed plastic pins which fit into this
square hole and locks the plate in position when the topbox is mounted.

[johnny]

greetings skidmore...

like the mayor of fredrikstad so elquently stated... i use 1/4 inch by 2 inch pipe insulaton tape called armaflex tape... it puts the pressure on there to hold that ricketty mess together...

once them nubbins lock in on the twist... that 22 liter is on the bung for good...

j o

[subforry]

The box fits to the rack and prevents the mount plate from moving.  The box will eat up the paint on the rack.

[skidmore]

Inge is a Mayor? THE Mayor??  :2thumbup: The honor is all mine!

The foam rubber is in place, Inge, and quite healthy looking. No signs of deterioration.

Subforry, I think you told me what I needed to hear. I will take a closer look at the bottom of the box to see how it could/should mate with the rack. All the paint on the rack can wear off as far as I am concerned as long as it fits fairly rigid!

Thanks for the material suggestion, Johnny!

[Motorhobo]

I got tired of the hellacious banging around back there so I got single-sided sticky rubber weatherstripping...



Cut it to the right width with a utility knife and lined the bottom of the case with it at all the contact points between box and rack...



Makes for a tight fit -- no banging, no rattling and less worry that the thing is going to pop off any minute. I did it the first time hell if I know how many years ago and replaced the weatherstrip just recently -- it's basically a one-time job.

While you're at it, consider replacing the lid retaining bracket, which prevents the lid from opening all the way backward. The original retaining bracket will eventually fail because it will eventually fail if it's bent repeatedly as will probably happen if you ever have the lid fly open while riding which I've done many times. Unless you lock the thing every time you close it it can come open unexpectedly and will catch wind, bending the retaining bracket --





Don't ask me how that penny got there. While you're at it, consider adding some bungee buddies to the case because there's no better place to hook a bungee than there -- hooking to the handles on the rear cowl will chip the paint and strapping directly over the seat will eventually damage the seat cover.



Hope this helps someone...

Van

[skidmore]

I resolved the sloppy box issue over the weekend. (get your mind out of the gutter!)

Van, your foam rubber idea worked great! That baby fits snug as a bug in a rug now. I is a happy motobricker!

I must admit....before crying out for help on the forum here, I never actually fastened the box to the plate, thus wasn't aware of how the rack contributes to immobilizing the box. All I had done was fit the plate onto the rack, realized how much the plate slopped around and bummed out. Before I embarked on the foam rubber mission, I fastened the box to the plate. Although the box did move around more than I thought necessary, it wasn't as much as I thought it would be based on how much slop the plate had on the rack. I now realize the plate requires generous movement to facilitate easy mating with the box and therefore the box to mate with the rack.

I found the exact package of foam rubber at Home Depot - about $8 after tax. I surrounded the perimeter of the box where it mates with the rack. Those two short strips in the middle, rather than stick'em to the box I chose to stick'em to the plate instead.

All in all it worked out excellent. I iced down about a gallon and a half worth of water bottles in my soft cooler, shoved the cooler into the box and rode all Sunday afternoon in the sweltering 97 degree heat.  The water stayed frigid cold, the box rode nice and solid, and although the ride wasn't quite on par with the exhilaration of a 70 degree Spring day, I had a kickass time with nary a give-a-shit to be had. :-)

While I was stopped for one of my breaks, I realized I didn't have the box lid properly latched  :mbird WTMF! I goofed around with it a couple minutes and learned its characteristics. My closing/latching technique is now perfected. I don't think I will have any trouble with the lid flying open.

[Motorhobo]

Glad it worked out -- I always wondered why BMW didn't design an overpriced rubber bushing to fit inside the bottom well of the top case to protect the rack, reduce the rattling, and tighten the fit.

Probably because you can get the ch1t for $8 at Home Depot.