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Discussion Starter #1 (Edited)
After finding a serious crack in the frame of my 900ss I have decided to bring my plans to strip and rebuild the 900ss forward some what. The crack was in the frame when I bought the bike but on a ride into town yesterday the bike started acting strange when going around corners at speed and under braking. A quick look at the crack and it appeared that it had grown a couple of millimetres. It wasn't until I looked at the under side of the frame after spraying some dye penetrant around the suspected crack and shone a black light on it that I found that the crack had spiralled around the frame and only a quarter of the diameter of the pipe was actually holding the frame together on the left hand side. Tonight after 4 hrs of carefully removing everything off the frame I have found a couple of other issues that I need to address so it was a pretty timely decision to pull it all apart when I did. The plan to make more exhaust pipes is going to have to wait for a bit. Decision time as to how far I am going to go with this. Colour change, blue frame with silver body work, Carbon wheels, Vee two high torque cams, cast iron brakes, 944 kit, upgraded suspension all round, the list goes on - let the "fun" begin ...........
 

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Sounds great. This is a good reminder to all to check for cracks periodically, and if you find one take care of it.
 

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Discussion Starter #3 (Edited)
Bike has been completely pulled apart and the frame is now sitting on the shop floor. Closer inspection of the crack has revealed that it is far worst than I first imagined. From what I have seen only one more decent bump would have resulted in the frame completelty failing. I have devised a repair scheme for the frame which will see the removal of the triangulated tubes from the top head stem area to the lower tube to gain access to the vital areas that need to be repaired before I can start the delicate process of removing the tank bracket/brace from the top tube. The cross brace tubes will be part of the replacement process as I am not impressed with the way they have been installed in the first place. I am now waiting to here back from a couple of companies in regards to 4130 prices which are wildly different around New Zealand. Picked up some S70 tig rods the other day specifically for the repair and the TIG welder has a new argon bottle fitted to it. There should be no hold ups on that front. "Home command" is less than impressed with the bike - she even passed the comment that I should have bought a Harley - shame on you Ducati, you should have fixed this problem properlly when it first became an issue. I am surprised that noboby in the US took them to court to force them to do a product recall and replacement of all frames back in the day. There are plenty of other examples of this happening for far less serious product recalls.
 

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I am surprised that noboby in the US took them to court to force them to do a product recall and replacement of all frames back in the day.
I hear that, loud and clear! It seems like enough of a safety issue to warrant a recall to me. After all, infant carseats get recalled when the buckle release button might get sticky and be difficult to operate. Not when the buckle is prone to cracking and failing, just hard to push!

Okay, getting off my soapbox rant. Good luck with the build! I'm excited to see what you do. Be sure to take good picks of your frame repair to inspire us (and by us I mean me ;) )
 

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Discussion Starter #7 (Edited)
]After a lot of swearing and cursing managed to get the bracket out of the frame with the use of a sabre saw and a heavy duty blade to cut it out. Will remove the two smaller frame tubes tomorrow and do some measuring and testing to see what material the tube is made from with the help of my Aircraft metal working mates. I have left the bearing races in there positions within the head tube to give the top of the tube a bit of protection while I work on it - the bearings need replacing anyway. As for the engine, I had a good look at the ports and everything seems to be in excellent condition, all the ports are pretty clean as well as the backs of the valves - no signs of any oil going down the side of the valve guides. One thing I did note though was that the port has had some pretty ugly cleaning of the intake port runners from the factor. It looks like the have machine the port off centre and then blended it out by hand. Have plans to get the heads CNC machined ports and manifolds, new VeeTwo high torque cams with matching longer valves , new valve guides, twin spark plug conversion and all the other bits and pieces for the heads.
 

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The frame material is not 4130. The repair manual says it is chromo but its just mild steel.
I keep hearing different things regarding frame material. I've heard that it is mild steel before and from other sources that it is indeed chromoly. Pajazo, can I ask how you confirmed this? And Combi, I'll be anxious to hear what your aerospace friends say as well. Looking good so far.
 

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Discussion Starter #9
It is concievable that parts of the frame are constructed from different grades of material based on the percieved loads that they are subject to. For example I would not expect the brackets that are the mounting points for the fairing to be made from CrMo steel as they get damaged pretty easily if the bike falls on its side. However the tubes that it is fitted to need to be alot more resilient and I would expect them to be of a stronger grade of material given that the tube wall thickness is so thin. In effect I would expect the main parts of the frame to be of a much greater tensile strenght then the parts of the frame that may be subject to random lowlevel accident enduced damage - a sacrificial or redundancey element.

The guys are looking into how we can determin if it is Cromo steel - at this point it looks like we will have to do a deflection test of the bits that I remove and see if they are what we think that they are. Either way, its going to be fixed once and for all and I will be making some additonal replacement brackets up for future use - it would appear that I am getting more and more people coming to me for work to be done on there bikes with a potentially similar issue.
 

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Discussion Starter #10
Have managed to remove the two small tubes from the frame with the minimal amount of fuss with a combination of the grinder with a cut off wheel and the sabre saw. Decided that it was safe to proceed with the grinder to clean the welds up and got into when all of sudden there was a cloud of steam. I found another problem in the frame - the tube connection to the head stem on one side was never welded completely. There was a small gap where there was no weld at all which had allowed water to track under the gusset through the gap and into the top frame tube. The crack had extended length ways down the pipe, travelling down the edge of the weld back towards the head stem as well as around the tube.
From what I can see with the sparks that come off the grinder though, they appear to be very different to those that come off a piece of mild steel. I can only conclude that the frame is made from something other than mild steel.
 

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Discussion Starter #11
Have had a chance to look at some of the other bits and pieces that I have removed from the bike. The outer tubes for the forks are absolutely shot. There are massive areas of corrosion under the anodising that is eating literally into the aluminium. I was going to repair them as I found that the area that alerted me to the fact that something was not right with them turned out to be not as bad as I first thought, but no. Further done the fork leg there was an area 5 times the size that was twice as bad. I had planned to get the forks rebuilt and now it will be a case of replacing both outer fork legs. Toying with the idea of getting the new ones re-anodised a darker shade of gold before sending them away to be rebuilt. Also looking at the prospect of getting a set of titanium nitride coated lower fork tubes as well. Looking at the rest of the bike bits latter today.
 

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Discussion Starter #12 (Edited)
Got impatient and decided to take the "Tim the tool man Taylor" approach today to get the frame all sorted with the grinder - what could possibly go wrong. As I started to grind the welds more steam and water came out. I have drilled a tiny hole and hung the frame up to let the water drain out but will get the heat gun on the frame and heat the tubes up to drive the water out as well. Concentrated on the actual welds from either side of the tube and got it down to a point where there was a line that formed between the old bracket and the weld. Once this formed it was simply a case of carefully breaking the weld from one side and twisting it off. Then a simple clean up of the remaining weld and presto all done. It was a bit more complicated to remove the remnants of the frame tubes from the out board part of the frame which was nothing more than an access issue. got here in the end though.
After a quick look at the frame again there are the start of a couple of other cracks while I was working away but nothing that can't be fixed tomorrow.
 

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frame metal!

Hi you are doing what i have been putting of for a while now.
will post pic's in the next day or so.
My question is what is the frame material iron,moly,soft steel etc or :think:
Italian cardboard.:confused:
As i want to get it welded locally it's a 4 hour trip to the frame welder.
I have a friend whom i can rely on.
I'll have to rig up a jig so it's all square and straight.
Cheers
Luckily i have another ride to keep me rolling on.
 

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Discussion Starter #15
After a bit of testing we have been able to work out that it is definitely Chrome moly steel that the frame is made from.
 

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Discussion Starter #17
We used a deflection test first up was the give away- the amount of force that was required to bend the tubes that I removed from the bike against a known tube of the same diameter and wall thickness in both cromolly and mild steel. The two Cromolly tubes bent at the same amount of force applied to them where the mild steel one took a lot less. It was very noticeable how much the tube actually sprang back after bending. The spark test was inconclusive. We also looked at the way the tubes were actually made. The tubes off the bike were totally seamless.
 

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Interesting. As far as I know CroMo is not usually MIG welded. Yield strengths of carbon steels overlap with that of chromo so I would think that deflection testing alone would not confirm if the tubing is indeed 4130 or some kind of non-alloy steel.
 

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I'm loving so many detailed pictures. Haven't seen as much detail on a frame repair before, super helpful, thanks!

BTW, isn't density of 4130 chromoly different than other steel alloys? Wouldn't the weight of a same size and wall thickness tube of mild steel to compared to the frame give a clue also? Although I can't really think why the workshop manual and the owners manual would both say Chromoly steel if it isn't. Nevertheless, i hear both from lots of different forums and sources.
 

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Great pics, mine was repaired too but the welding as as great.
i used the Nichols kit, 2 years later and no issue....

i don't know why but i do not like showing the chassis or reg number of my bike on the internet...
 
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