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Old April 1st, 2019, 07:31 PM   #46
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Quote:
Originally Posted by pat1098 View Post
While I'm visiting (and I have to confess I haven't read this thread right back) but there was usually a cause of those aluminium swing-arms on those '90s 2-valves cracking (and many did).
IE. a maladjusted (too-tight) chain, or (more likely) a failing and 'bottoming' shocker. The shockers didn't last long, and a passenger (or a big rider) could bottom them out, resulting in this sort of cracking.
Check closely around the base where the shock mounts to the swing-arm also. MIght be worth a better (or at least rebuilt) shock while you're doing so much work.

As you didn't read all the way from the beginning I'll try to summarize as best I can.



My swing arm was cracked underneath the chain slider on the top and bottom of the swing arm. It was also cracked the full height on the back side. None of which was visible as it was either hidden behind the chain slider or on the back side of the swing arm facing the engine.



It could well have been a misaligned or mis-tensioned chain that caused it. I don't think it was the shock, but the shock was completely shot. I doubt there is any fluid left inside.



The shock mount area is fine, no cracks. If there were, they'd have revealed themselves after the trip through the steam washer. That's when the cracks around the pivot were revealed. As the swing arm was mis-shimmed when I got it, my guess is either that was the cause of the cracks, or a result of them.



No longer matters, as the cracks were "V" grooved out and TIG welded by a certified structural welder/welding instructor. I bought a new to me shock shortly after bringing the bike home. I got a later Sachs which is about 12mm longer than the Showa that I took out .



I have made some progress in the last few weeks so my next post should cover that if anyone cares to follow further.....sean
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Last edited by NorCal996; April 1st, 2019 at 07:37 PM.
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Old April 1st, 2019, 08:00 PM   #47
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Swing arm is now finished. I decided not to polish the entire thing. As was pointed out previously, it's a great deal of hard work and no one is going to see the inside under the hugger, or the bottom. So I just painted the rough cast parts and the parts that wouldn't be seen.







Also removed, wire wheeled and cleaned the valve access covers. Here's a before and after in the same shot:



Both of these are from the vertical cylinder. The upper one is the exhaust valve cover and the lower one is the intake valve cover.


Finally finished sanding the frame and got the paint down on it yesterday. I decided on matte gold for the frame color. To accomplish the look I was after, I used Dupli-Color wheel paint in gold and then matte clear over it also from Dupli-Color.







Today I intended to put the triples back on but ran into a snag. The bearings I ordered did not fit the steering stem so I have to find ones with a slightly larger ID.



In the process of getting all the parts cleaned up for install, I test fit the front axle to the new to me forks. The right side fits fine but the left side threaded insert was slightly larger as the forks are from a later bike. No big deal I thought, just remove the old insert from the leaky old forks.



THAT was a disaster of sorts. I didn't have much confidence the insert would be in reasonable shape as the rest of the bike was been such a nightmare. I wasn't wrong on that count.



The insert refused to come out. The one in the new forks came right out with a little pressure once I loosened the pinch bolts. The old one, not so much. I ended up driving a screw driver into the pinch slots and even then it was really difficult to remove. When I finally got it out after an hour or so, I realized why.



Some numpty used a center punch to peen the outboard end, mushrooming it in the process. I'm guessing to prevent the insert from moving. Just leaving the pinch bolts tight would have accomplished that without deforming the insert.



After some work with a mill file, and my drill press I was able to "mill" the distorted insert back to spec.




The OEM insert removed from the new forks on the left and the old repaired one on the right. Note the marks on the insert from a pipe wrench or vice-grips. I couldn't get those out without milling too much material off and making the insert too small to use.



Finally, I ordered another group of parts from Ducati Omaha. Probably will have to order a couple more still. For now, I'm stalled until I find new bearing roller cones. At least on getting to a rolling chassis. To that end, I also bought one of these from MotoWheels:



I'll post an update once I have bearings installed on the steering stem and the front end installed. THEN I can use the frame tool to mount the swing arm. Got a lot of work to do on the engine before it is ready for the frame to mounted to it. More later........sean
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1993 Ducati 900SS


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2004 GSXR 600
1992 GSXR 750 oil boiler
1983 XN85 Turbo
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Old May 13th, 2019, 05:51 PM   #48
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Just a quick update....
Steering head bearings installed, lower triple and forks installed, swing arm installed on the frame tool which is temporarily bolted in the frame in place of the engine.



Rear wheel is done, refinished and clear coated. Looks pretty good too, if I say so myself. I'll post pics of that once I'm ready.



Tank is block sanded and primered. One more coat of primer is needed once the current coat is block sanded with some 330 grit.



Handle bars have been refinished, and I got a new to me subframe from eBay as I found the original one too badly deformed to use. I'd repaired the one obvious broken tube but then I found broken welds.



When viewed from above there was a distinct parallelogramming of the subframe. The left side was about an inch and a half farther ahead of the right side.



On closer inspection I decided the only way to correctly repair it would be to cut the entire thing apart and straighten all the tubes before welding back together. Too much work. No pattern to work from either, so straightening would be hit or miss.



Easier and less time consuming to just buy a new to me one from eBay. The one I have now is actually straight, save for a minor ding in one tube.



Aside from all that, I have a number of things left to order. I've been to look at tires this weekend, and got some 90 degree aluminum valve stems. To my dismay, those did not fit. Tires at my local Cycle Gear were older than I'd like to spend on. At least, the ones I want anyway.



I got new to me switch pods for both sides. The left side though, it needs more attention than I wanted to give it.



It has parts that are not broken on my original but broken parts that I'll have to replace using ones from the original.



In other words, I'll have to make 1 good one from 2 broken ones.



Things are coming along. Not as fast as I'd like but I'm hoping to be done here in a couple of weeks.....sean
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My garage:
Twins:
2000.5 Aprilia Mille R
2000 Ducati 996
1996 Kawasaki EX500 basket case
1993 Ducati 900SS


Suzuki collection
2004 GSXR 600
1992 GSXR 750 oil boiler
1983 XN85 Turbo
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