You could go with lock-tite, but myself, I'm a through bolt and locknut kinda guy. Or, depending on your particular box/mount, go through existing holes into bars isolated from wearing on the underside of the rack by rubber.

 

That bracket (I just removed mine today so I've been staring at it) looks plenty weak already to me. It's cast pot metal from what I can tell. MAYBE aluminum, I didn't assay it, but I would loop U-bolts around it before I drilled any holes and if I drilled holes they would be backed by backing plates/washers and nuts.

 

Drilled.........

I had a spare rack and drilled 4 holes in it for top box plate.......then J.B.Welded nuts to the underside of the rack. This way I can screw down a bolt from the top and not worry about the nut turning. So far, 900 miles w/o any problems.

 

Yes, I drilled and tapped the holes for 4 screws to hold my Bestem mounting plate down. I got sick and tired of messing with the brackets that came with the box. No problems so far.

Jim

 

I would drill and tap them - and then fit a helicoil insert...apply a small bit of bearing grade threadlocker to the helicoil so it never moves..and then use some blue threadlocker on what ever bolt you use to screw into the helicoil...

 

I tapped into it using the existing holes and used 4 screws to fasten a Bestem case. There's only about 1/4 inch of metal there and as someone said, it's not steel. This setup is not particularly strong but it does work. If your loads are light it might be all you need. I like the idea of U-bolts, I might try that one day.

Peter

 

I abuse my rack all the time.

I frequently take my rack off, attach something to it, then put it back on.
The rubber pad is almost always sitting on a shelf instead of going with me.
I use the existing holes, and use screws going upward through the existing holes in the rack, into a slab of plywood (I have several slabs for several purposes). There are 30-mm holes in the plywood so I can get at the bolts that attach the rack to the bike.

With the slab secured to the rack, and the rack secured to the bike, I screw a box of some kind to the top of the plywood slab, and maybe add some eye-bolts so I can sling my tent or sleeping bag under the slab, where sensible people put $300 saddlebags of some kind.

The box that generally goes on the plywood slab is a 96-liter Wal-Mart Action Packer. This box has carried my gear from Florida to Virginia, Texas, Ontario, and Arizona. From Ontario it has carried gear to Newfoundland and around two Great Lakes. Next week I will load it up for my second try to reach British Columbia from Florida.

Yeah, my load is top-heavy, and I am a pushover for wind, but I generally get where I am going, and all my stuff comes with me and stays dry.

I totally ignore the 10-kilogram limit for loads on the rack.
I put two hundred pounds on the rack and it holds that overload just fine.
Keith

 

I have well nuts installed. If you pinch the top of the nut, you can feed it through from the bottom and then it essentially becomes a captive nut. This is PERFECT for installing a top case.

 

bestem and stock rack

Drilling and tapping cast aluminum is asking for trouble using steel bolts. Especially if it is load bearing as a backrest.


For maximum strength and durability I installed a bestem box using 5/16 square headed bolts from the underside of the rack. The square heads index perfectly between the cast ribs on the underside of the stock rack. I elongated the holes on the bestem case adaptor to give it some adjustment fore and aft. Finished it with stainless fender washers and nylocks on top and cut the end of the bolts off flush with the nylocks.

 

Just pull off the rubber cover and you have 5 holes to bolt through.

 

I bought an Amotostuff rack, without the Givi mount, for my Wee last winter as I wanted to be able to change between a bicycle carrier, my top box, and a milk crate easily (and without taking off the luggage rack as I have the Givi side mounts on also). Although at first Ididn't want to spend the money, I'm glad I did. I really like it, and it may be worth considering if you intend to take the top case mount on and off. My top case is Bestem "Rattler".