How to tackle a cracked frame?

[Hart89]

OK well i went riding at a mates motocross track and was doing all the jumps having heaps of fun then i noticed a crack at the base of the steering stem at the gusset. So then i pulled the tank to give it a weld to find that the frame under the tank was cracked through. these were full sized jumps, whoops and rhythm sections not exactly the thing that suits a 25 year old bike, a trail bike at that.

I'm 17 who wants to give the welding ago and not spend money on someone doing it and charging more than the worth of the bike itself. I was thinking of finding steel tubing, cut it in half then place it over the original and weld. Sound good? How do the professional do it? I've only got a stick welder if that will affect anything. With this repaired crack does it hurt the overall rigidity of the frame? Anything else i should look into doing?

thanks for any information you can give me
Harty

 

[tuckers20]

my dad had an yamaha xj900 and the frame underneath where the pillion sits cracked. he got some flat metal and made gussets out of them. I would weld the crack and then put a piece of tubing around that to be safe. A stick welder should work. Thats wot we used

 

[Peer Lovell]

If you love ourself you should give this job to a professional welder.
I can't imagine it costing that much.

 

[Hart89]

This is the second frame ive broken. I have another but whats the point , itll break aswell. I will look into getting someone do it but yeah im poor so i might see if i could get it done for free by a trailer maker my mate works for.

 

[rm_racer]

If you are going to do it your self, you should do what tuckers20 said. Weld up the cracks then put a steel sleeve over it for more strength. The only differnece is I would use a MIG or TIG welder.

That being said, it would probably be much better to have a professional do it.

 

[Ol'89r]

The only differnece is I would use a MIG or TIG welder.
QUOTE]

Harty.

I agree with rm_racer. Use a tig or mig welder rather than a stick welder. Grind out the crack to a vee about three quarters of the way through the metal and then fill it with a bead. Gloving or gusseting over the crack is a good idea. Use a similar thickness metal to the frame and weld it intermittently. Or in other words, weld around the edge about a 1/2" and then leave a gap of about a 1/4" without weld and so on. This allows your gusset to move and flex a little without cracking.

If you do all of the fabrication of the gusset and grinding yourself, a pro welder should not charge you very much to weld it with a tig or mig welder.

Just my $ .02

 

[Hart89]

Yeah if i had better access to a MIG or TIG i would use one i hate stick. My dad said that it would be possible to use strips of 5mm thick 1cm wide and about 150mm long and bridge the crack. I think a tube sleeve would give it more strength. Ol'89r you say about letting the gusset flex without cracking but what about the crack?

 

[Ol'89r]

I think a tube sleeve would give it more strength. Ol'89r you say about letting the gusset flex without cracking but what about the crack?

Repair the crack first.
Grind out the crack and fill it with weld. Then, lay the gusset over the crack for added strength.

If you weld the gusset all the way around it will cause what is known as a 'stress riser'. Or in other words, a place for a new crack to start. By intermittently welding the gusset, it allows it to flex a little and distributes the stress along the whole tube.

I would not use a stick, (arc) welder. Arc welders produce too hot of a weld and can crystallize the metal around the weld actually making it weaker. Best way would be a tig. Second best, a mig. Arc welders work good on very thick metal, such as farm equipment, tractors, etc.

I agree with the tube sleeve. But don't go too thick with your sleeve or gusset or it can cause a stress riser. Your gusset should not be thicker than the tubing. Generally only 1/2 to 3/4's as thick.

 

[yz250ryder]

I'm a professional tig welder, and depending on the size of the crack, it might cost more than what you think. if your do most of the work yourself like getting it ready for welding and prep the area meaning taking off the paint, any rust that might be around it.it shouldent be to bad. I would use tig because you could gind the crack and then dig in deep with the tig to fix the crack. Then cut a piece and weld it it, but u have to make sure the filler that you are using and the base metal, "meaning the frame" are the same, and who ever you get to weld it make sure the weld are complete and have no under cut around the welds and where they stop the welds ther aare no holes or creaters. this will lead to future probles because they can make stress risers which will make the plate that got welded on and the frame around it weak. I would check around before taking your frame to just any old welder, ask then if they have the right stuff to do what you want done and see if you know any one else that got things fixed there. If you have any more questions E-Mail me!