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Not a luggage expert, and freely admit total ignorance, but I have worked with both types and offer this....

• The "seat belt latch" is implemented by bolting a flat "latch plate" to the rear of the rack. This rack is steel, and a small flat mounting plate is welded to the rear of the rack, parallel to the license plate. The latch plate is attached to the mounting plate by 2 bolts which sit in large enough clearance holes that some position adjustment is allowed.

• The second type of luggage use a single "pawl" or "claw", which through a clawing action caused by the closure of the attachment buckle, reaches around the round tube of the luggage frame and pulls the luggage onto the frame. As the attachment latch goes "over center" a steady holding pressure is exerted.

In my total ignorance, I have actually had the unfortunate luck to convert the seat belt type frame to use the claw type luggage. Not an exercise I recommend. You seem to have the opposite set of racks, and so are missing the welded-on mounting plate.

You might check to see if a flat plate could possibly be run across the area of the license plate between the 2 racks. You would mount these 2 places on each rack with an Adel clamp. (Click Here for example.) Then you'd have a place to drill the 2 holes per side to attach the missing "latch plate". Otherwise it's buy new luggage or buy new racks. 🙁

Hope this helps.

Thanks for your detailed answer. That's what is was looking for. BMW has something like the adel clamp for that purpose. Of course, it's $15 each. On order, I'll find out in a week when they arrive...

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A solid rack / platform system ::
You'll need to have, for a secure rack, with 4 legs [points] of the attachments to a frame. the early rack had 2-3 points, some owners only knew of 2.

these 4 include for earlier type krauser rack systems found on mid 70's on machines . . . . . the stock rear bmw frame rail lug [ top of pannier attachment] , foot anchor lug and rear anchor lugs. the rear anchor lugs include the frame attached to the fender top as well as the below the license plate loop that incorporates the same bolts that attach the seat belt pannier latch plates. IF you do not have a secure rack the vibration WILL crack something on your bike frame.

the foot frame lug keeps the rack frame from vibrating and cracking the rear bike seat frame @ the top anchor attachments.

the below the license plate loop also keeps vibration to a minimum and or swinging of a load inside the pannier and rack stability. so your rear frame rail won't crack.

a smart thing to add to your rack is a set of ROC-STRAPS that circle round the rack and pannier because the seat belt latch can give way @ times. i have a 1'' flat strap @ the rear and a fastex buckle t hold the panniers in situ. i don't like the strap round the pannier because if .... IF you forget to attach it, it melts off the exhaust pipe or slips off the bike and you just lost one.

1'' flat strap is readily available at any hardware / backpack store and in a pinch the fastex can be found in ANY FOOD store parking lot that has shopping carts. heck twine can be used w/ the fastex couplers until you get a good start back when lost.

adding a front krauser frame metal tab to re-inforce the front plastic secure tab to the frame insures the loss of the krauser. plastic breaks off with age. one tab outside, one inside.

put your name on the pannier if lost a finder can notify you.

I also add '' FOOTMAN'' hardware to the 4 top corners of the krausers. i can attach bungees or 1'' strapping for tents, bags, chair anything to the top of the krausers.

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NOTE : : the capacity of krausers is 22 pounds max
I've fabricated several rack systems. I have a dozen + mods done to this type system

photos included

ps i would NEVER use an adel clip to hold anything of significant weight on any rack system. glad it's yours.

BMW has something like the adel clamp for that purpose. Of course, it's $15 each.

At that low price it's safe to bet the BMW logo isn't emblazoned on it !!! 😛

the seat belt latch on it. It's just round tubing with no way to connect the seat belt latch. My panniers use that type of latch. So do I need to get a different rack? How does the latchless rack work?

the seat latch or any latch connects to the downward rack frame shown in photos. the seat latch uses 2 10mm bolts for attachment. this connection connects the upper, latch anchor and lower rack loop together. all three are important for a complete system to minimize vibration when panniers are used. if your rack doesn't have these two anchor holes then you may not have a krauser rack.

or

the PO modified it somehow.

i have yet to swap out my seat belt latch with the newer type latch also shown in fotos. that involves modifying your original rack , possibly cutting or removing the latch buckle anchor. that depends on your rack system.