This is what happens when you do not wear glasses!

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Quest

Quest

Joined
Oct 21, 2014
Messages
70
Location
Alberta, Canada
Okay the spring tune-up was going great, adding new parts... Life was good!

Grab the 1/2" torque wrench, checked the torque specs and went to tighten the pinch bolts on the rear swing-arm. Without glasses I thought I saw 250 ft.lbs.!

WRONG!!!!! The lower pinch bolt area is cracked......

Okay for all you mechanical wizards, can this crack in the swing-arm casting be welded? I have access to very expert welding crew..... they are pipeline welders and have experience with aluminum...


Thanks
 

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Wait, time out. First did you say that you grabbed a 1/2" torque wrench to tighten an M12 bolt into an aluminum piece? Second did you say you thought the reference said 250ft lb? Your kidding right? Considering we use a 1/2 torque wrench and a 169.64ft lb for a wheel nut. You were not scratching your head just a little at the thought of 250ft lb?. I can be welded but please take it to a good TIG shop. The "pipline crew" comment is just going to take this situation to the next level.
 
Like I said, forgot to put on my reading glasses. Old age necessity! I thought I was reading 250 ft. lbs., hence the 1/2" torque wrench and not 3/8"....

Not proud of my mistake... but I am not going to blame anyone else - I screwed up!!!

With regards to welding the swing-arm, I doubt I am the first idiot who has made this mistake... so the questions were:
1) what type of welding? - thank you for suggesting TIG
2) Any special preparations? Heating swing-arm?
3) Any finishing after the welding process? Grinding,, Painting......

Thaks Endodoc
 
Sorry for being a ........ Had one of those days. Well actually, that is no excuse. Im just a ........So first no you are not the first and will not be the last. I think the alloy in the arm is 356 and is heat treated so you will have to weld accordingly and you should heat treat after the weld. Either way, the arm is coming off the bike. If you want to replace it and you have an 1199, they are fairly easy to get. If its a 1299, they are a bit more difficult. Someone might want to chime in on the difference between the 1199 and and the 1299. Anyhow, used, undamaged is in the $600.00 range. If you do have the ability to remove the part and you have access to a machine/fab shop, you can fix it. You will have to grind it out, fill it, machine the hub clamp then sand and finish the repair. Then you should heat treat the part. You do not absolutely have to but I would. If you have the cash, just get a used one. If not then its going to be a chore.
 
whomever you choose to weld this would be wise to bevel it. After that you're looking at very little weldable material. It's apparently heat treated to some degree since it cracked instead of just folding/tearing.

That mean's you're likely looking at having to pre-heat the weld area and maybe draw it back to prevent it from cracking after it cools. Im hardly a welder myself. Speaking solely from my days doing mold machining and my heat treating experience in that realm.

I will say i've rarely seen already heat treated materials go back together and stay together after more heat has been introduced. but good luck!
 
Quest said:
Like I said, forgot to put on my reading glasses. Old age necessity! I thought I was reading 250 ft. lbs., hence the 1/2" torque wrench and not 3/8"....

Not proud of my mistake... but I am not going to blame anyone else - I screwed up!!!

With regards to welding the swing-arm, I doubt I am the first idiot who has made this mistake... so the questions were:
1) what type of welding? - thank you for suggesting TIG
2) Any special preparations? Heating swing-arm?
3) Any finishing after the welding process? Grinding,, Painting......

Thaks Endodoc
Click to expand...

Well in 5 years on the forum first time I saw this so I think maybe you are the first idiot that did this.

Sorry mate. :) But you set your self up for this.

In all seriousness give the weld a shot but perhaps you can find a wrecked bike and get the swing arm off it that has not been damaged.
 
First off. I skipped all these other replies, which I will go back and read afterward man.

I once had a 748R I raced for a few years. It had the SAME crack there which was always in the back of my mind while riding the bike. Do NOT take this as the Golden Truth on your end (My stupid disclaimer attempt) But I rode it for a while like that without ANY incident . The other Pinch Bolt carries enough strength to see things tight enough and in check without any issues - HOWEVER - Yes, I eventually had a highly qualified Welder put a quick touch to it which still enabled me to use the bolt. It CAN BE welded - imagine if you had to replace that ENTIRE SwingArm buddy??? :(

Again, you make the last call on it of course man.
 
I can't believe somebody is going to risk his life over this, there is no way in hell I will take a chance of not coming back home and don't see my kids going to high school because I want to save $600. HOW CAN SOMEBODY TELL THIS GUY TO FIX THIS ....?????

you got a $20k motorcycle you .... up stop trying to save money playing mechanic. Go to church and thank god you notice in your garage and not in the street where kids are playing. Imagine getting hit with a ....... tire.How would you feel if a motorcycle tire hit you just because somebody wants to play mechanic?


Hey jenny how you dad died?
well.. one day he broke some part of his 20k bike and a member of a motorcycle forum assume dad was smart enough to fix the part but dad can't boil water without checking youtube, so dad when and took the part to joe the plumber to weld the part after Joe fix the part dad jump on the bike for a test drive 30 min later the rear tire came off the bike, the rest of the bike landed on Dad body, brake fluid spill on his ass and the rear Ohlins TTX shock penetrated my father ass. He dies with a smile on his face and my mother got the insurance money and married Joe the plumber.
 
esmirna8261980 said:
I can't believe somebody is going to risk his life over this, there is no way in hell I will take a chance of not coming back home and don't see my kids going to high school because I want to save $600. HOW CAN SOMEBODY TELL THIS GUY TO FIX THIS ....?????

you got a $20k motorcycle you .... up stop trying to save money playing mechanic. Go to church and thank god you notice in your garage and not in the street where kids are playing. Imagine getting hit with a ....... tire.How would you feel if a motorcycle tire hit you just because somebody wants to play mechanic?


Hey jenny how you dad died?
well.. one day he broke some part of his 20k bike and a member of a motorcycle forum assume dad was smart enough to fix the part but dad can't boil water without checking youtube, so dad when and took the part to joe the plumber to weld the part after Joe fix the part dad jump on the bike for a test drive 30 min later the rear tire came off the bike, the rest of the bike landed on Dad body, brake fluid spill on his ass and the rear Ohlins TTX shock penetrated my father ass. He dies with a smile on his face and my mother got the insurance money and married Joe the plumber.
Click to expand...

Im not 100% but I think what he's saying is that with a little JB weld it might good to go
 
I've got to give credit to Quest for his honesty. Because I've seen several of these broken swing arms at the pinch area and in every case the owners blamed Ducati.

Yeah I'd replace it , I trust endo's opinion I just don't trust welders and my bad luck .

Plus I'd just want it right and you're going to have hundreds of dollars in messing around with it anyway welding heat treating painting eff that

call a dealer and get a brand new one coming IMO
 
Screw it. Just weld the whole damn hub and swingarm together. A nice giant bead all the way around both sides. Problem solved and you can save weight by removing the pinch bolts and, no more hassles with chain adjustment.
 
Don't feel bad I did the same same damn thing twice,that alone should make you feel better.both times I thought I can go a hair more then that happened.The second time I was at nyst I did 2 sessions & I thought to my self eehh let me just tighten the chain a touch,then it broke.Maaann I was so damn pissed & felt like a jack ass i ended up packing it up & going back home after about a 3 hr drive to get there.

I didn't want to take any chances I bought a used one off eBay.
 
The precision of the contact face of the stock bolts is not very good so theoretically, that could be problematic if you cycle these bolts often or out of torque sequence. Seeing how my first bike is a test bed for successes and failures, I have cycled these pinch bolts probably 40 times. I use good hardware, proper assembly lubricants I torque sequence the bolts in an alternating fashion in 5nm increments to spec and I use a Proto digital wrench. The design is not a problem as long as procedures are in place. Dog .... torque wrenches can be out by a bunch. You cascade a bad wrench with improper lubrication and a bad sequence and you can fairly easily exceed the limits in this clamp design.
 

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