1971 /5 Krauser Bag Frame Weld Repair

NCmotomark · May 23, 2013

The tubular frame on my /5 that holds R/H Krauser bag has a tab that holds the tail rack on it that needs to be welded where a stress crack has formed.My inquiry is what is the best kind of weld for this type of repair?Not too sure what kind of metal was used.I have the black painted type of carrier so I cant see under the paint to determine if its steel or a alloy.I do know that where the stress crack is it has rust on some of the cracked surface.Would appreciate any input,don't want to use wrong kind of weld and cause a worse problem.
Thanks

Darryl Cainey · May 23, 2013

I think most of the racks were Braised with bronze.

Any competent welder should be able to do this!

lmo1131 · May 23, 2013

"Alloy" (aluminum) doesn't rust.

As Darryl stated, they're steel, and brazed. In my experience, once something has been brazed, it will have to be brazed if it needs repair; the brass and flux penetrates and contaminates the steel making it a PITA to "weld".

I'd suggest pulling the whole rig off the bike and having the frames bead, or media, blasted to see if there are any other cracks starting to develop. When I bought my Krausers (used) I was going to have them stripped and powder coated. Once the powder-coater got the old finish off we found a couple of "iffy" joints.

Post a few shots if you have time. I'm curious as to what "vintage" your hardware is. Duane Ausherman maintains a "Krauser" thread, and he's always looking for images.

guenner · May 23, 2013

I have a friend who has a muffler shop. The welder there just used a grinder to strip off the paint and put some "blobs" on it. I painted it over with black paint. Holds just find and I can't even remember how long ago this was done.

/Guenther

barron_williams · May 23, 2013

Lew, is that your rack in the picture you posted? Looks like mine (except I have chrome), but I never knew what brand it was. I have BMW city cases.

Barron

SCBuckeye · May 23, 2013

My 2 cents

I have the exact frame, and someone before me "brazed" it in several places - appeared to be whoever had it before me carried something on the back "deck" and they put in some supports.

When I cleaned off a ton of paint, I found a hairline crack at the point where it attaches to the behind-the-seat frame mount.

My suggestion: don't braze, but have it tig welded. Much nicer job, cleaner looking, and stronger. Once you braze, which isn't that strong, you will never be able to weld anywhere near it.

lmo1131 · May 23, 2013

Yeah Barron, my rack.

Jimmy, I agree, TIG puts much less heat into the structure than brazing would.

I've seen some Krauser hardware that looked "welded" (by virtue of the size and shape of the bead) ... maybe they switched at some point (?)

NCmotomark · May 23, 2013

lmo1131 said:
"Alloy" (aluminum) doesn't rust.

As Darryl stated, they're steel, and brazed. In my experience, once something has been brazed, it will have to be brazed if it needs repair; the brass and flux penetrates and contaminates the steel making it a PITA to "weld".

I'd suggest pulling the whole rig off the bike and having the frames bead, or media, blasted to see if there are any other cracks starting to develop. When I bought my Krausers (used) I was going to have them stripped and powder coated. Once the powder-coater got the old finish off we found a couple of "iffy" joints.

Post a few shots if you have time. I'm curious as to what "vintage" your hardware is. Duane Ausherman maintains a "Krauser" thread, and he's always looking for images.

Lew,
Thanks for the reply.My luggage carrier looks similar to the photo you posted,but is a three piece assembly.R&L halves bolted to the rearsubframe and center mounted rear rack that attaches to the R&L halves.Has BMW stamped on end that connects to upper shock mount bolt.I will use a dremel with a wire brush and remove the paint around the stress crack and nearby weld and see what color the weld is.I guess a brazed joint will be a brass color. :dunno

lmo1131 · May 24, 2013

I guess a brazed joint will be a brass color.

That is correct.

70816 · May 13, 2015

SCBuckeye · May 14, 2015

I have the same bag frames as pictured, and when paint was stripped, they were full of cracks. Previous owner(s) had tried to have brazed and then covered up the mess with extra-thick paint.

I stripped mine, ground off all erratic welds, and ground out all the brazing.

What I did, was to come up with some thoughtful supporting and cut pieces to look nice with nice fits. Then, I had TIG welded, but then did some MIG myself. ground, polished, and then re-painted. I suspect they will never break again. I do not, however, use them for a back bag or rack just behind the seat, just use for Krauser side bags.

IMO, this design of the racks was suspect from the get-go. The metal is so flimsy and also soft (probably because the designers thought the frames would "give" but not break). However the design was awful! Nearly everyone I know has had to have them welded/brazed, etc.

Final opinion, do not braze as it will cause problems later on and will then preclude welding altogether.

Omega Man · May 14, 2015

jimmylee said:
Final opinion, do not braze as it will cause problems later on and will then preclude welding altogether.

Like soldering, welding is best done with the metal clean. It is a bugger to remove brazing. There is a place for it but not here IMO.
One thing I have noticed welding on my F800 parts, the German paint is really attached- and stinky.
OM

lkchris · May 14, 2015

jimmylee said:
IMO, this design of the racks was suspect from the get-go. The metal is so flimsy and also soft (probably because the designers thought the frames would "give" but not break). However the design was awful! Nearly everyone I know has had to have them welded/brazed, etc.

BMW gets blamed for all sorts of things all the time and almost always this is wrong.

For the most part, broken bag racks are simply evidence the bags have been overloaded. The specs are clear.

No argument the specs are pretty low and I suspect I never left on a trip with them fully loaded when the weight wasn't over specification. Not much for washboard roads either.

swall · May 15, 2015

On brazing vs welding--if the part was originally brazed with brass/bronze weld, you need to stick with this for repair. It you attempt to weld, be it TIG, MIG or oxy-acetylene, you will develop liquid metal embrittlement cracks.

SCBuckeye · May 15, 2015

lkchris said:
BMW gets blamed for all sorts of things all the time and almost always this is wrong.

For the most part, broken bag racks are simply evidence the bags have been overloaded. The specs are clear.

No argument the specs are pretty low and I suspect I never left on a trip with them fully loaded when the weight wasn't over specification. Not much for washboard roads either.

That's like trying to defend the design because it's stated capacity is 5 lbs. (or whatever light limit per your statement) when everyone knows using them for their stated purpose will ultimately overload them in normal use.

Just face it. This was just a simply poor design (whether they stated limits or not) and could easily have been designed so this cracking and breaking would never have happened.

The design should have been aborted!!

Perhaps they will design a 1,000 cc motorcycle and state that one should not go over 20 mph. (just to cover their a$$$$$).

1971 /5 Krauser Bag Frame Weld Repair

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