Tiger 885 frame cracked

[coachgeo]

... Of course there's no more info on this site than the pictures, don't know how its been ridden.....

hit the link...  your questions are answered there.

[nightrunner]

Notice how the crack followed the edge of a weld bead?  Notice how that bead is fairly high compared to the bead below it?  When you have a sharp transition from thin metal to thick, it creates a stress riser.  It is mostly likely place for cracks to form.  Once it started there, that crack just propagated on around the tube.

[Sin_Tiger]

Notice how the crack followed the edge of a weld bead?  Notice how that bead is fairly high compared to the bead below it?  When you have a sharp transition from thin metal to thick, it creates a stress riser.  It is mostly likely place for cracks to form.  Once it started there, that crack just propagated on around the tube.

I'd second that, the only way I could explain the crack position, plus you always get some carbon depletion either side of a steel weld which leaves that area more brittle. Definately a maufacturing fault, a possible contributary factor might be base metal being too cold / not preheated before welding or shocked, i.e. chucked out in the British rain before it had normalised  :lol:

[oxnsox]

Thanks for those comments guys

[coachgeo]

Sin and Night ..... your explanations sound plausible.  The question now is.... if say your not in Europe where you can find Tiger Frames... and was left to fixing this one...   What would you do?

Other questions:

. what characteristics would you look for to give one a hint that their bike might succumb to the same cracks as it gets older.
. While we got a bike apart what can we do to make sure our bike does not succumb to that as it gets older.

[nightrunner]

I agree that looks like a 'cold' weld.  Even pre-heating the metal to 150-200F improves weld penetration.  Since welding generates a lot of heat, this is taken care of, except when you first start on a cold piece.  Note the weld below the crack is a very good one.  

On fixing that frame, I would probably give it a try if I were in your shoes.  The expert welders can correct me if I'm wrong.  I would first grind the cold weld down flush.  I would probably take it to someone skilled in TIG welding.  You could use arc or MIG but those are a greater thermal shock to the metal.  TIG is very controlled and should give good penetration.  At least this is what a master welder I know told me.   I would find a skilled welder/fabricator rather than some mechanic dude who happens to have a welder in his shop.  

You'll want to make sure you can apply the proper clamping force to close up that crack so you'll keep the proper steering rake.  Here is where it gets tricky.  It looks like the crack has propagated around past the shroud thing on the bottom of the spine.  So you'll have to figure the best way to weld up the whole crack.  That may mean grinding off the shroud piece, or cutting out a strip of it to allow access to the spine.  Then weld it back when you are done.  That is not an easy repair but I think the frame can be saved.  

On your second question, I have never heard of cracked frames being a problem with the steamers.  That one may have been in a front-ender or someone tried to jump it.  If you are asking about how you might add some bracing to reinforce it,  you might weld some narrow strips of steel right across the new weld to beef up that section of spine.   Maybe 1/2" wide and 2" long or so, and in a few places around the circumference.   Note that is my gut opinion, not that of a mechanical engineer.

[Sin_Tiger]

You're right Coach' you're not having much luck at all.

Definately worth a shot, personally I think it can be recovered to 99% if done preoperly. wouldn't bother with adding extra metal, it will just give you problems when putting the other stuff back on and really strips / gussets are only any use to redistribute loads to a bigger structure. The steamer tube is the same diameter all the way so no benefit.

Find an experienced welder, preferably with aero / marine / petrochem work under his belt. Process should be to drill a couple of 6mm holes at the extreme ends of the main tube to feed in and exhaust sheilding gas. Drill the extreme ends of the crack 3 - 4mm holes should be plenty. Prep the cracks down leaving around 20 - 30% of the wall thinckness remaining. Preheat to around 60 deg C and TIG a root weld with shielding gas flowing internally then 2nd and 3rd pass as required, plug the gas holes. Cover the lot with a thermal, non flamable, blanket and let it cool naturally. If you are really concerned ask to have NDT done on the weld, Magnaflux or X-Ray is a bit overkill for something like this and difficult for this size, dye penetrant will be quite adequate.

We do MS hydraulic pipe like this that is good for over 200 bar in addition to high vibration and shock loads.

I am not an ASME coded welder but I have to be able to inspect and more importantly spot a fudged weld.

I am not writing this for the welders benefit, he will know and probably have his own preferences for prepping the job, this is for your benefit, so that you will have more confidence you have found somone who at least knows what they should be doing and you won't have to annoy them while they work, just stand and observe, welders don't tend to like being distracted when they are concentrating  

[coachgeo]

You're right Coach' you're not having much luck at all....

Yes my luck has been Shiat lately, but dont jinx me.... this bike with cracked frame is not mine.  Just asking questions to educate myself.  

If I recall right the lucky fellow with the cracked frame is from Europe so he should be able to find a replacement frame much easier than one of us here in the states.