TIG welding cast section of motorcycle frame

[mangocrazy]

Hi,

I've just bought a motorbike (an Aprilia Falco) that has a fractured section on a cast part of the main frame where the subframe mounts to it (see photo below)

What would be the best way to weld this? Any particular technique, filler rod etc. that would be best?

Cheers,

Graham

 

[julieanncharters]

tig welded with 4043 filler wire looks thick section from photo so will need to be vee'd before welding.
might have to do a partial strip down to get access to the inside weld.

 

[chevy2]

Motorcycle ali i've welded on frames and parts tends to be gererally poor quality and can be difficult to weld,
Spend a bit more time prepping it and you'll probably need more a/c balance on cleaning to help it weld nicer.

 

[stuvy]

has that been down the road?

either that or the throbbing twin has shook itself to pieces

 

[julieanncharters]

when welding cast Ali with tig it usually requires multiple passes with no filler wire /stainless brushing to boil all the crap to the surface.
when you have clean material then you can think about welding the two halfs together.
don't think about welding the parts together without the above process unless you want it looking like ****.

 

[DrNik]

silly question maybe but what aluminium is used when they cast car/bike bits, as it doesnt seem like normal stuff

 

[shenion]

Frames are normal aluminum but I'm not sure the specifics.

Many of the add-n parts are magnesium alloys similar to Zamak. Nasty stuff to weld due to the zinc content.

I did the footpedal bracket on my ZX6R, took multiple passes to boil out the zinc and get some 4043 filler in.

 

[Shox Dr]

Varies a lot, I've welded a fairbit of Honda parts from modified sumps to cases, and they weld very nicely. So do some Suzuki etc parts but others seem to be made from any thing but aluminum

 

[mangocrazy]

has that been down the road?

either that or the throbbing twin has shook itself to pieces

I don't honestly know - it's not something I've ever seen before on a Falco, so there has to have been some fairly heavy impact to cause it. But the rest of the bike is in very good nick, with no evidence of any sliding down the road.

I'll certainly take all the comments on board; now I just need to find a qualified welder in the Stafford or Sheffield area to hand it to (I'm not qualified!). And yes, I intend to remove tank, seat, seat plastics and as much of the subframe as I can before handing it over.

 

[stuvy]

The reason I asked is the could have stuck new crank cases, levers, mirrors etc but the rear frame could be the expensive part.

There a nice bike to ride, they tend to stand on the back wheel a lot

 

[chevy2]

To echoe what others have said,
a lot of motorcycle aluminium looks like ali but seems to have very little ali of any quality in there.

 

[mangocrazy]

The reason I asked is the could have stuck new crank cases, levers, mirrors etc but the rear frame could be the expensive part.

That's the weird thing - unless all the plastics, exhausts, bars etc have been replaced then it looks original. But you'd hardly do that on an '03 bike that isn't worth much above £1.2k.

There a nice bike to ride, they tend to stand on the back wheel a lot

They are - very under-rated and lots of grins per pound...

 

[Woody.v8]

The broken item seems to only be supporting only the subframe, Just see if you can get a Good weld on the cast section and all will be fine (if you can weld)

 

[stuvy]

It's does seem very odd though.

I know millies had swing arm issues but never a frame!

 

[mangocrazy]

The broken item seems to only be supporting only the subframe, Just see if you can get a Good weld on the cast section and all will be fine (if you can weld)

Yes, it's not part of the main chassis/frame. That piece only supports the subframe, and it's only one of four subframe mounting points.

I can't weld (not ali, anyway). But I intend to find a Man who Can...

 

[Woody.v8]

Yes, it's not part of the main chassis/frame. That piece only supports the subframe, and it's only one of four subframe mounting points.

I can't weld (not ali, anyway). But I intend to find a Man who Can...

I reckon with a man that can weld you are on a winner for your frame repair
It is some what important to keep the rider on board But in the grand scheme of stresses its pretty low.

 

[willmckeand]

Hi,

I've just bought a motorbike (an Aprilia Falco) that has a fractured section on a cast part of the main frame where the subframe mounts to it (see photo below)

What would be the best way to weld this? Any particular technique, filler rod etc. that would be best?

Cheers,

Graham

Hi Graham,

I've got a Falco with the exact same split in the casting, did you determine the cause? Mine gradually split and is now completely separated. Did you have to do any re-bending of the frame to get the two parts to meet again? Mine has about a 3mm gap.

Any advice would be much appreciated!

Cheers,
Will

 

[Richard.]

Welcome to my world. I have literally done loads of bike casings swing arms etc.
these are not fun to weld and contain lots of unfriendly stuff in them that makes welding difficult. One of them is silicon which is why is important to use s Si filler (4043/4047).

when welding cast Ali with tig it usually requires multiple passes with no filler wire /stainless brushing to boil all the crap to the surface.
when you have clean material then you can think about welding the two halfs together.
don't think about welding the parts together without the above process unless you want it looking like ****.

I personally don't recommend this as by putting in a number of hot passes to draw out the cr#p you risk distorting the part before you've welded and if it's a frame or swing arm then as you know you don't want to change its shape at all.
V out the crack and clean it again and again spend a good hour on getting the prep spot on as you really only get one chance. Use acetone also. A lower form of pre heat is good and will help to draw out rubbish and get the Ali preped to flow. I'd suggest getting this as close to a flat position as possible. I know that's not easy but will help out loads if your able to lay the bike down even 45degrees will help. Best of luck.

 

[Richard.]

Motorcycle ali i've welded on frames and parts tends to be gererally poor quality and can be difficult to weld,
Spend a bit more time prepping it and you'll probably need more a/c balance on cleaning to help it weld nicer.

This is a very good point. On normal Alu welding I'd use 65-70% dcen on the balance. With bike Alu it's more like 55-60 so that there is a bigger % of the ac wave in the positive to help with cleaning.

 

[chevy2]

This is a very good point. On normal Alu welding I'd use 65-70% dcen on the balance. With bike Alu it's more like 55-60 so that there is a bigger % of the ac wave in the positive to help with cleaning.

Likewise, i run similar numbers.