Cracked motorcycle frame...help!

admin

Hello, I am very new to this forum but thought this would be the best place to get some opinions as to what to do to repair this frame. I am speaking about a 1967 Triumph Motocycle frame. I know the frame is mild steel. The crack is around the front motormount and down tube. This frame has been powdercoated but will obviously be stripped and cleaned before any repairs are done. My questions are,1) can this be fixed?2) what would be the best way?3) can it be fixed without it being a noticable repair?Thank you for your input! Attached Images
Reply:Lighten up the images for better detail.Show a larger picture of the greater frame area, please.Blackbird
Reply:Yes it can be fixed, cut out the broken section & tig in a new piece with internal slugs on either end & fab a new motor mount.
Reply:here are some better pictures, I hope this helps. Attached Images
Reply:Sand/grind the paint off in the area where it is cracked, some of it may just be cracked brittle paint.Looks like cracking started at top of mount in picture 2 and 3, looks like cold lapped mig bead.Grind out all the existing welds next to the crack area and V out the crack itself, stop drill the ends of the crack.Weld it up, preferably with tig, stress relieve after welding with an O/A torch.Keep an eye on it in use, if it keeps on cracking you may have to sleeve it like Old Skool said.thats what I would do."The reason we are here is that we are not all there"SA 200Idealarc TM 300 300MM 200MM 25130a SpoolgunPrecision Tig 375Invertec V350 ProSC-32 CS 12 Wire FeederOxweld/Purox O/AArcAirHypertherm Powermax 85LN25
Reply:I think Skool's method is a lot more work but you are guaranteed a good repair.  Consider cascading the fillet welds past the ends of the mounting plates say half or three quarters of an inch.  ( you run the fillet along past the plate tapering it down)  Cascading would remove the stress riser.  Common practice on heavy equipment.
Reply:Piece of cake.Grinder..Tig Machine..And someone that knows what's what and you would never know anything....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I agree with everyone else. I worked on the Harley Frame welding line for a couple a years in the 90's (welded on 130 a shift) and I don't miss that one bit.Last edited by bobhdus; 11-08-2012 at 02:53 PM.
Reply:Is that painted clump in the second pic a weld ?350P 30A spool gun cut master 51  syncro 250 other stuff " take a dog off the street and make him prosper and he will not bite you sad the same cannot be said for man" i didnt use punctuation just to piss you off
Reply:I'll throw my hat in the ring and say you should add a tube gusset fillet in there. Weld that thing up well, then make a tube fillet to cover a section say right up between the 2 tabs, and weld it in. You should still have clearance for the engine to mount. I have seen plenty of frames welded and then stress crack right near the weld area because whatever harmonic made it cut loose in the first place was still a factor. A pretty thin tube section would do this well; 1020 DOM in say .065- .083 would be plenty good; make it about 1-1.25" beyond the crack area. Roll the edges of the gusset fillet round, leave no hard 90 degree corner to create a stressor.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:It must be an aftermarket rigid frame. As such it may have other design, material or workmanship defects.  I am not sure exactly what years but the origional frames had some cracking issues as well, up around the steering neck if I recall correctly.The title says help, why not figure out what years the frames with suspention were good and use stuff of that vintage?sorry my answer has nothing to do with welding.
Reply:Originally Posted by Old SkoolYes it can be fixed, cut out the broken section & tig in a new piece with internal slugs on either end & fab a new motor mount.
Reply:Here's the way I do them when stretching backbones or down tubes.Cut out broken section with a cut off wheel, square on both ends Discard cracked piece .Drill 2 holes opposite each other just above the topcut & 2 holes just below the bottom cut. Machine slugs for a slip fit in existing frame. Whatever length you make the slugs mark center on them. Insert them into frame top & bottom flush with your cut. Cut replacement section slightly shorter than the piece you cut out leaving a gap top & bottom you're comfortable tigging. Using a pick through the drilled holes slide the slugs until you have the centers you marked visable in the gaps. Plug weld the 4 holes you drilled which will hold the slugs in position then tig out both joints .You may have to scribe a line lengthwise down the slugs & centerpunch a series of holes for the pick to bite if the slugs are snug. Clean up with a flap disc & you have an invisable repair.Last edited by Old Skool; 11-09-2012 at 11:53 AM.REAL TRUCKS DON'T HAVE SPARK PLUGS