Seeking advice/thoughts re: frame repair.

[Boxerboy]

1982 R100RS, left front downtube, incorporating the horizontal brace.:thumbs_down::icon_cry:

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/cracksinframe004.jpg

Can you see it?
http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/cracksinframe006.jpg

Thoughts and advice appreciated.

[DarthRider]

What happened Box?

[jamming]

Stop drill the crack at the ends to relieve the stress and TIG it. You could use a MIG welder but I'd suggest TIG just to control the heat. I'd be real interested to find out why it failed the way it did...history..etc.

[Boxerboy]

Thanks lads. TIG it is on Thursday.

What happened? Well, I found this big crack, but only after removing a fairing cheek to do some other stuff. It might've been there for years? There was a butt of rust in it..which I've wiped off. Crack, cheek, butt, wipe...do you think I may be venting here? ;)

Advice from another R100RS rider, who happens to be a professional welder.


With tig I would run 1st and 2nd weld over the crack itself continuing past the crack at each end by 3/4"
Subsequent runs being on either side of the first run stopping 1/2" short of the previous run.
I would clean all paint from the weld area and not remove any frame metal prior to the first run, the first run would require just enough filler rod to fill the crack flush with the surface of the frame with the aim of full depth fusion.

As for the history...no signs of sidecar use.
The bike has fallen on either side in the past. The damage at the time, (except for my drop 18months back) is unknown. Fairing bits have been repaired but the nature of the accidents I know not of!

The position of the crack is considered very unusual, and most have thought more due to stresses thru the frame, instead of accident damage. I guess I'll never know!

[Boxerboy]

I have a professional welder, with experience on m/c frames coming around to fix this Thursday.

I've stripped the area of everything easy to do.

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/cracksinframe006.jpg

How far away d'ya think any wiring should be? I can "insulate" with wet rags I suppose?

Tank is off, carbs dry, relays removed, battery disconnected, access made easy, steering damper removed, brake line shifted, fairing off, horn removed......

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/Mytempsupportfix-1.jpg

[Sir Limpsalot]

Bummer. God knows what caused it. Should repair OK though. Sounds like you've done all you can to make it easy for the welder. Good luck.

Si.

[Arby]

I wonder if loosing the motor mount bolts and retorquing after the repair is completed would help relieve any possible stress points?

Good luck with the repair BB. Sounds like your welder guy knows what he's doing.

RB

[Donson]

It looks fairly new,as their doesnt appear to be rust down inside the hairline.I cant imagine what would cause that type of crack in that location.Check all the rest of the frame junctures as closely as possible,for other possible fractures.Srop drill and weld multiple passes,oh yeah Youre doing that......

[Boxerboy]

Eyeball inspection of the rest of the frame shows no nasty surprizes. I released the 4 engine mounts wondering if the gap might close, then retorqued them, but they were all fine.

[Capt. Nemo]

Your welder guy might have a heat shield blanket he can surround the welding area with but a big very damp bath towel works fine too.
Also, you probably already know (I didn't read all of the posts) to disconnect the battery just to be safe.
As clean as TIG is, one can still get damage to a wire or, from one tiny piece of molten metal.

[Boxerboy]

All those precautions were carefully taken. Job is done.

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/prep.jpg

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/cracksinframe012.jpg

http://i228.photobucket.com/albums/ee256/hansea/BMW%20Frame%20cracks/painted.jpg

Everything is back on the bike and ready to do a 1500k weekend ride...
I hope it doesn't crack again!!!

[jamming]

I hope it doesn't crack again!!!

It won't. A properly done weld is stronger than the surrounding material. Nice work! Thanks for keeping the Old girl running, your a good mate.

The BMW Airheads are my first love. Broke my touring cherry on an R90S at 16. A duffelbag, bungies, 100 bucks, and riding gear. I was king of the road. Of course it was my Dad's and he didn't know I was riding it to meet him and my Mom in New Mexico.........but that's another story. :pot:

[DarthRider]

Nice weld, looks good.

[Dirty Doug]

Weld Smeld........... a couple wraps of duct tape and you're ready to go. They even make duct tape in black so you wouldn't need to paint it either. Another plus is duct tape won't rust.




O.K. I'll give you the weld. Looks like a nice job. I envy those that can do neat work. When I weld something I'll spend two hours with the side grinder removing about 10mm of metal I didn't really need.


Dirty Doug

[DJ Down Under]

Looks good Steve.. :eusa_clap:

There'll be no holding back on your big ride this weekend now.

DJ