Grinding welds smooth on SSA (s2r swingarm)

[Airborne]

I remember seeing a thread about grinding smooth the casting marks on their stock triple clamps which came out really well. I was wondering if grinding down the bead on the weld off my SSA on my s2r is asking for trouble? I'm not sure if that bead is excess weld material or if it would affect the integrity of the weld? What process does ducati use to weld the ssa? MIG? TIG? Maybe I could research it more if I knew that information? I am going to have it powder coated by He man and I think it would look pretty killer all smoothed out and PCed black.

I'm also wondering how uniformly i would have to polish the entire arm since its all getting pc'ed anyway?

[scduc]

Not knowing how the seams looked before welding, I would have to say that it is probably not a good idea. If the seams had chamfers around them , then the weld would fill the void and grinding may not be an issue, but if no chamfer, the weld is really just bonding the two pieces and grinding will remove the bond.

[1KDS]

It's definitely tiged

[Duck-Stew]

I don't know that I would mess with the weld per-se, but there is a large-ish casting ridge through the cast front portion that can be smoothed off w/o fear of structural integrity.

On this bike, I also had the access hole for the suspension bolt filled as it uses a different rear suspension, but if you look at the smoothness of the arm, you can see versus a stocker what I'm talking about:

[mendoje]

...I was wondering if grinding down the bead on the weld off my SSA on my s2r is asking for trouble? I'm not sure if that bead is excess weld material or if it would affect the integrity of the weld? What process does ducati use to weld the ssa? MIG? TIG?

If you research it, you'll find the process does not matter.  Weld bead height is specified on weldment drawings, and a certified welder will achieve exactly what is called out by the engineers. Too little bead will scrap a part, too much bead takes more time (these guys get paid by the part), risks overheating the weld and base metal, and costs more (filler rod and inerting gas).  Never grind the beads of a structurally important weld!

[He Man]

i would not grind it off. well firstly you shouldnt use a grinding disc. that will eat through the swingarm faster than inmagine. You can smoothen it out, but that doesnt make much of a difference. I'd leave it alone.

[Charlief]

Once it is pc'ed black you will not notice the welds

[jwoconnor]

The only time I have seen "Bead height" called out is when there is melt-through and a reinforcement to the back of the material is called for. The height of reinforcement is called out.
That's not to say you should remove the weld profile from your swingarm.

[MotoCreations]

As Duck-Stew alluded to, feel free to grind the raised casting area off.  No structural loss as a result.  The TIG weld bead?  You can lightly lightly lightly (emphasis here) cleanup for cosmetic.  Leave 85%+ of the weld at least.  Never deeper than the TIG weld ripples.  Why?  This is the weakest part of the S*R series swingarms -- that plus the HAZ (Heat Affected Zone) from welding.  I've seen a number of S*R swingarms tapped from behind and they have a strong propensity for cracking/breaking in this specific area. 

If you badly desire to make the TIG weld disappear -- there are ways.  In small areas, grind the weld and v-groove and then reweld it yourself if you are qualifed. Be careful of creating distortion.  "Heat Normalize" when done to minimize the HAZ areas.  Not for the timid of course.  I've only seen one person do it in five years so far.

Simplest course of action is paint; do a brushed finish; or powdercoat.  Look for examples throughout the DMF done by others.

Best advice is thus:  if that particular weld bothers you -- inevitably the frame welds themselves will drive you insane too.  Go have a beer and learn to love the warts.  Else build you own swingarm and frame jigs and build your own parts then with beautiful welds and higher quality materials.  (hint -- I took this second course of action and it is time consuming to be honest in pursuit of perfectionism...)

[Airborne]

Thanks everyone. I have not, up until now, seen bead height called out on a drawing so I thought I might be able to get away with it. I'm not going to risk doing it after all the advice. The risk is not worth the effort to make it look good only in my own eyes.

The casting mark might go, however it is warming up and I want to get it out for PC soon and back on my bike so I can ride. Either way its coming off this friday.

[gatorgrizz27]

Another option is to fillet all of the weld areas with bondo and then paint instead of powder coat it.  Hopefully the swingarm doesn't flex enough for it to crack off.

[Duck-Stew]

Another option is to fillet all of the weld areas with bondo and then paint instead of powder coat it.  Hopefully the swingarm doesn't flex enough for it to crack off.

If you use a metal based two-part epoxy, it will stand up to the oven baking of the P'coat and then you could fillet the welds like described above and still powdercoat...

[He Man]

If you use a metal based two-part epoxy, it will stand up to the oven baking of the P'coat and then you could fillet the welds like described above and still powdercoat...

Metal Lab works pretty well. its not exactly cheap, but cheap enough.