Repairing Aluminum Frame?

[emayn15]

A buddy of mine bought a F4 off craigslist that was in pretty rough shape. After ripping it all apart and putting together a parts list he noticed that he has a stress crack in the frame. Is it possible to Tig weld minor frame cracks and bring the bike back to a safe condition? I'm kind of hesitant he's planning on welding it but I told him I'm not sure you can safely repair an aluminum frame. I have a few pics of the crack on imageshack if anyone has an opinion on whether he should write the bike off or if it can be repaired. Thanks!

http://img26.imageshack.us/g/crack1m.jpg/

[Jim]

Wirelessly posted (Doc sucks: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

Was it purchased in MA with a title ? I think you may be better off going back to the seller

[Eric Baker]

That looks to be into the cast part of the frame. I wouldn't chance it unless you have an EXCELLENT welder to do it for you.

[emayn15]

That looks to be into the cast part of the frame. I wouldn't chance it unless you have an EXCELLENT welder to do it for you.

When you say cast you are looking at the crack to the right of the weld on the polished portion right? The crack goes from the polished part down through the weld seam. The guy who is going to ride the bike will probably ride it more like a cruiser than a sportbike. I'm just trying to keep a buddy safe if the frame stands a chance of it coming apart. He also has to take in to consideration the likelyhood of someone getting killed if he fixes things then flips it too. No one wants to sell something that could come apart at the frame if someone were to drop the front end real hard one time.

[Eric Baker]

Well there's that one you may be be able to repair, but then I see another hairline crack to the left, really visible in the third picture, that is directly across the cast portion. Doesn't look too safe. There's a lot of stress in that area.

[Stromper]

Was it stunted ?

Anything can be repaired. Unknown cost but I would weld it then flaten (grind) it down a little and then make a small plate that can span from one side to the other plus 2 inches and weld that over the top

[Fowl998]

You have to be very careful welding aluminum as you probably know. Knowing what the base metal is i.e. 6061-T6, 7072 etc. the correct filler wire needs to be used for a sound weld. Also when you weld aluminum the heat affected zone around the weld will become annealed so for instance if the base metal is 6061-T6 after welding the heat affected zone will be equal to a 6061-T0. I am not sure if bike manufacturers heat treat their frames after welding or not but I would guess they do. Some of the original strength can be restored through heat treating.

So I would say if you do decide to have it welded make sure it is by someone that really knows what they are doing with aluminum. It's one thing to be able to weld aluminum but it's quite another to know exactly what happens to it as a result of welding and how to make sure the weld is sound.

[BostonSVkid]

deleted

[butcher bergs]

I have a host of parts for that bike including a frame.

[emayn15]

I have a host of parts for that bike including a frame.

Sweet I'll point him in your direction. He needs a good number of parts so he more than likely might want to buy some stuff off you. He's been pretty bummed about how much stuff he's found that needs to be replaced.

[gmdboston]

I can look at it, but the F4's are not know for stress cracks. Either it was crashed real hard(and in that case you need to have it measured to check alignment and rake angle as well as inspect the steering head bearing bore) or was beaten like a red haired step child by some Icy Hot Stunna' yo. If you bring me a rolling chassis I can check it for you for $100 before your buddy gets too deep into it.

[KB]

Put the thing back together and ride it like you never saw the crack.

KB