MOTOBRICK.COM

TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: BobR on March 14, 2012, 05:26:00 PM

Title: tragkorb Weld Repair
Post by: BobR on March 14, 2012, 05:26:00 PM: I have a split on the inside of one of my side cases (91 K100RS), right on the inside edge of the gasket groove (see photo). Evaluating repair options and wondered about welding the split together with a soldering iron or some similar tool. Have looked at a few You Tube videos of this being done, but did not know if the material used for these cases was the type that could be welded together. Anyone have any experience with this?
Title: Re: tragkorb Weld Repair
Post by: DRxBMW on March 14, 2012, 09:40:36 PM: Quote from: BobR on March 14, 2012, 05:26:00 PM
I have a split on the inside of one of my side cases (91 K100RS), right on the inside edge of the gasket groove (see photo). Evaluating repair options and wondered about welding the split together with a soldering iron or some similar tool. Have looked at a few You Tube videos of this being done, but did not know if the material used for these cases was the type that could be welded together. Anyone have any experience with this?
I've have R&R cracked cases with marine grade resin and cloth,inside application. JB Weld on Frank's touring bags, as an experiment last summer. Both have seen numerous miles with NO issues.

FWIW, when my city bags took a second hit, the marine glass repaired section held up very well.

Harbor Freight has a plastic weld kit but I'm dubious that would work with the type of plastic used for the BMW bags. Someone on the KBMW list tried welding with poor results. CRS on what the material actually is currently,ABS maybe ?
Title: Re: tragkorb Weld Repair
Post by: wmax351 on March 15, 2012, 01:31:29 AM: The inside is tricky: It is HDPE. The outside is ABS, so I just use ABS pipe cement from Home Depot. I have some scrap Black ABS I bought at TAP plastics. I used some of that to reinforce.

I also repaired my front cowling with the ABS scrap and Cement. Looks great, and I have a place to mount good turn signals.
Title: Re: tragkorb Weld Repair
Post by: Nickh on March 15, 2012, 10:09:33 AM: Hi Bob,

I did exactly that with my tragkorb lids, although it was in a different area well within the main lid, in the bottom leading corners.

I used a soldering iron with a chisel tip, and waited until it was very hot, using gravity to help I melted the case, directly on the cracks, on the inside surface, and let the plastic "pool" back into the crack. with a bit of help from the hot iron. The results didn't look very pretty as the ABS will harden very quickly away from the heat, but it hardens sufficiently to be rubbed down with a bit of "wet'n dry" paper (done gently, otherwise it gets hot again).

I don't know if there was any deformation or discolouring on the outside surfaces, as they sit behind the applied rubber trim, but I now have two leak free tragkorbs which look fine .. . on the outside anyway.

I have no idea if this would work on the area you have to fix, if nothing else you could stop the crack lengthening by applying heat to the ends of the crack. I would also consider using some support on the reverse side whilst you carry out this fix. It is also very likely that you may have to do both sides.

All the best,

Nickh
Title: Re: tragkorb Weld Repair
Post by: BobR on March 15, 2012, 12:36:28 PM: Some great feedback from all three of you. Thanks. I went ahead and made the repair using a soldering iron and some filler from a plastic bag for the wide areas. It actually turned out pretty good. Not sure how well it would work on the outside abs material though.

Once I finished it, I opened my other tragkorb and had to laugh as that one is missing about a third of the inner lip area. Completely gone!! So now I am scratching my head on what to do. I wonder if the marine fiberglass fix would be the best approach, seeing as I have to build the entire lip area. Suppose the other choice would be to try and weld a strip of plastic in there. Any thoughts would be appreciated.
Title: Re: tragkorb Weld Repair
Post by: Inge K. on March 16, 2012, 01:03:48 AM: Another possibility is to cut away the broken piece of the lip, then fold a strip of sheet metal
(only as wide as the gasket pocket on the rear side), add some sealant and rivets.

(http://i496.photobucket.com/albums/rr326/IngeKarlsen/Reparasjonsideveske001.jpg)

Inge K.
Title: Re: tragkorb Weld Repair
Post by: BobR on March 16, 2012, 09:39:52 PM: Quote from: Inge K. on March 16, 2012, 01:03:48 AM
Another possibility is to cut away the broken piece of the lip, then fold a strip of sheet metal
(only as wide as the gasket pocket on the rear side), add some sealant and rivets.

(http://i496.photobucket.com/albums/rr326/IngeKarlsen/Reparasjonsideveske001.jpg)

Inge K.

Interesting. I need some education on rivet guns then, as I have never used one. It appears they do not need to go entirely through the wall, is that correct? What type of rivet gun should I be looking at? One of my straps is also pulled out, so I can use it on that as well. Thanks.....
Title: Re: tragkorb Weld Repair
Post by: frankenduck on March 16, 2012, 10:12:25 PM: Riveting is quite easy. Just get one of these from any hardware store - ask a for a "pop rivet gun."

(http://hardwareaisle.thisoldhouse.com/images/2008/10/31/pop_rivet.gif)
Title: Re: tragkorb Weld Repair
Post by: Inge K. on March 16, 2012, 10:35:09 PM: Quote from: BobR on March 16, 2012, 09:39:52 PM
It appears they do not need to go entirely through the wall, is that correct?
One of my straps is also pulled out, so I can use it on that as well. Thanks.....

The bags have a double wall where the rivets is mounted, you need to drill through the inner part.

I think I did use rivets that was 3,2 x 6 mm (this work was done more than 20 years ago),
which was the longest one I could use...the space available at the rear sets/limits the lenght.
Drill one hole and measure the deept to the second wall.

The rivet tool is easy to use..open the handle..insert the rivet in the nossle...push the rivet into
the hole hold it with some pressure against the collar...squeese the handle until the pin breaks.

Inge K.