Aluminum welding

[sdcr]

I am looking at a vintage motorcycle from th 90’s. It currently has a crack in the aluminum swingarm. The crack is along the pivot area, where the SA attaches to the rear of the engine.

I plan to remove the swingarm arm, and have it welded. Can anyone recommend a good alloy welder?

[Perazzimx14]

I am looking at a vintage motorcycle from th 90’s. It currently has a crack in the aluminum swingarm. The crack is along the pivot area, where the SA attaches to the rear of the engine.

I plan to remove the swingarm arm, and have it welded. Can anyone recommend a good alloy welder?

Ducati 900 SS/SP?

Any weld shop worth it salt can help.

[sdcr]

Ducati 900 SS/SP?

Any weld shop worth it salt can help.

Actually, it’s a 1993 750SS. Here is a picture of the crack. It in a critical area, which is stressed by the pinch bolt.


 

[Perazzimx14]

Actually, it’s a 1993 750SS. Here is a picture of the crack. It in a critical area, which is stressed by the pinch bolt.

The swingarm on my 900ss/sp cracked on the other side so it was easy to wash over the crack and refuse the metal. Your's while fixable may also require some machining to get opening back to round and the proper diameter. Have you looked for a good used one? That might be the more cost effective route?

There is an aluminum one on the big auction site for $579.00 or you could maybe downgrade to a steel swingarm for 1/10th the price. There is some interchangeability there. My 900ss/cr's have steel swingarms the ss/sp was aluminum with an undeslung brake caliper.

[sdcr]

No, just started the looking process, and saw the crack. I like the bike, so may go with the purchase.the less expensive CR Ducati 900, had a metal swingarm arm. I may go with that one.

[nc43bsa]

I would be leery of welding an aluminum swingarm at that particular location.  A metallurgist once told me that aluminum alloys "have a memory", in that accumulated stresses add up until the part fails.  Failure of this part in a high-speed sweeping curve would be hairy, to say the least.

As mentioned, I would go with a good used part rather than trying to repair that one.

[nc43bsa]

Also, when I tried to view the photo, the hosting site (imgbb) wanted a subscription. 

Has it come to this, that a subscription is required to view photos in addition to posting them?

[sdcr]

Also, when I tried to view the photo, the hosting site (imgbb) wanted a subscription. 

Has it come to this, that a subscription is required to view photos in addition to posting them?

I saved the photo from an auction site, so I get the same prompt.

[cliffrod]

I saved the photo from an auction site, so I get the same prompt.

I also got the prompt on this specific photo, but didn’t get it on imgbb image from another thread. 

[Dukedesmo]

Quote from: sdcr on August 25, 2025, 06:28:53 PM

Actually, it’s a 1993 750SS. Here is a picture of the crack. It in a critical area, which is stressed by the pinch bolt.

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I had the same thing happen on my Ducati Monster, although the swingarm was an 851/888 racing item with the bracing. Apparently they were renowned for cracking until they modified them for later models using a different grade of alloy and making them a little thicker in that area.

I was originally going to weld mine but I actually had a later (non-braced) improved model so I used that instead, I left the cracked one with a welder friend to repair but, for one reason or another it never got done.

The advice I got was to stick with the newer model as it likely won't crack, the older stuff was not really good enough but I don't know if that also applies to SS models of the era?

I didn't know mine had cracked until, when riding along the rear end felt 'loose' almost like a puncture. When I looked down at the swingarm pivot this is what I saw;

The spindle was completely out of the swingarm on the chain side so the whole rear end was flexing under power. Initially I thought the pinch bolts had loosened as the cracks weren't visible until I got a really good look at home as they were underneath

Here's the break on one side;

And the other;

I think it would be best to get a new swingarm if at all possible.

[sdcr]

Thanks for all the tips on this Ducati swing arm arm. I am now in agreement, that replacing the swing arm is the best path.

Anyone here know what year Ducati upgraded the part? There are many advertised on eBay, but it’s challenging to tell what one are the upgrade.

 Also, Since the bike will not be tracked, but just a rider, I may go with the steel, CR swingarm.

[Perazzimx14]

Thanks for all the tips on this Ducati swing arm arm. I am now in agreement, that replacing the swing arm is the best path.

Anyone here know what year Ducati upgraded the part? There are many advertised on eBay, but it’s challenging to tell what one are the upgrade.

 Also, Since the bike will not be tracked, but just a rider, I may go with the steel, CR swingarm.

Also make sure the swingarm is a match and also the brake caliper mount and spacers. If memory serves the SS/CR had a 160 rear and the SS/SP had a 180 rear. The CRW brake caliper was up top the SP was underslung.

I have no doubt that multiple years and models super sport/monster will fit is just finding the right combo

A side note on the steel vs the aluminum swingarm on the super sport the difference even for a track bike is probably negligible. The aluminum with underslung caliper is undoubtedly 90's era kewl factor and that's about all.

[sdcr]

I missed out on the Ducati 750SS. Went for more than I wanted to pay, with transport costs and needing a new swingarm arm, +.

[Perazzimx14]

I missed out on the Ducati 750SS. Went for more than I wanted to pay, with transport costs and needing a new swingarm arm, +.

Good one to miss. Wait for a 900ss to pop up.

Also when dealing with 2V air cooled super sports make sure you check the frame at the headstock. Early models were prone to cracking.