Part flew off bike, need help

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You really don't need it, All you need is a dab of JB Weld. :lol: Tell us about the motor and what you had done to it.
 
Tom,
that's scarey lookin.
What happened an IED go off inside the cases?
Don't show that to Pre-Deal or there will be no deal :p
Probably could put it on ebay and tell how Paul Dunstall blew it up on the5th turn of theIsle of Mann in 1972 :twisted:
Just feelin naughty
Marshal
 
Will one of you kind gents please post the picture ?
I don't want to join Facebook just to see what fell off.
Thanks, (I feel like I'm missing something) graeme.
 
Thank you Nortom1, I was missing out on something !

That's the second air cooled crank I've seen !

Oh dear,,,,,,
 
I built this motor for my buddy Eric Swortsfigure in 1990 when we were both racing. His good crank fell off the shelf in the big 89 quake, we used another crank we had laying around.

It broke because when it was balanced at the factory, too much material was ground off the bottom of the flywheel weight so they needed to remove some from the top for balance. They used the same 1/2' drill, drilling a few shallow holes in the thin area between the journals, weakening it severly. It held up in a street bike but not at the track.

Eric was leading the race at Sears Point @ 120mph when it let loose, It destroyed most of the bike, blew a chunk into his leg (requiring stiches) and showered the followers w/ hot shrapnel . Ken Armann still has the engine for laughs.

I'm new to Nortons fourms, I've been riding, racing and working on them since I got my MKIIA in 78', but left them alone for years while I raced Ducatis. I've been fixing them up a little lately and came across this forum. The Newbies cracked me up w/their problems, prompting this post. I know everything about what fails on these bikes and how to fix them. Racing them played a big role in my career as a Mechanical / Reliability Engineer.

I've put up some old (and new, see the trackmaster) Norton stuff on my FB page (if you have access):
http://www.facebook.com/home.php?#/prof ... ef=profile

Can someone tell me how to upload photos here? I have more to share.

Tom
 
It looks a lot like the bottom end of one that let go during prototype testing, but the top end of ours lunched itself too. The test rider was running on the Motor Industries Association test track in Nuneaton, UK. It's a tri-oval with banked turns. The top lane on the banking gives zero side-force at 85 mph. He was at full throttle, doing an endurance test, and was at about 110 mph when the final drive chain broke. The tacho needle was bent about 30 degrees where it hit the end stop.

After the inquest, the gurus figured the engine had revved to maybe 10,000 rpm and the valves floated. Thr piston hit the valves and bent them, and the impact cracked the piston all the way from the crown to the skirt through the wrist-pin bearing holes. The cracked piston then jammed in the bore, but the con-rod continued down, ripping through the small-end bearing and the skirt. At the bottom of the stroke, the rod, with the wrist-pin still in it, dropped out of the cylinder into the crank-case and then out the side.

This was the final indication that a 1/4" chain wasn't up to the task. The other bike in the test fleet was quickly modified to 3/8" chain so that its engine would still be a valid long-term test article.

It was fortunate that the rider had the presence of mind to pull the clutch to prevent so much damage that we couldn't have figured out the cause. He was also lucky not to get clobbered by the protoype XJ6 Jaguar that was sharing the track with us that day. We finally found the split link on the track. The spring clip must have failed, becuse the two pins rivetted to the other side plate were at about a 30-degree angle, pulled out of line when the tractive effort was no longer symmetrical.
 
Nortom1 said:
I built this motor for my buddy Eric Swortsfigure in 1990 when we were both racing. His good crank fell off the shelf in the big 89 quake, we used another crank we had laying around.

It broke because when it was balanced at the factory, too much material was ground off the bottom of the flywheel weight so they needed to remove some from the top for balance. They used the same 1/2' drill, drilling a few shallow holes in the thin area between the journals, weakening it severly. It held up in a street bike but not at the track.

Eric was leading the race at Sears Point @ 120mph when it let loose, It destroyed most of the bike, blew a chunk into his leg (requiring stiches) and showered the followers w/ hot shrapnel . Ken Armann still has the engine for laughs.

I'm new to Nortons fourms, I've been riding, racing and working on them since I got my MKIIA in 78', but left them alone for years while I raced Ducatis. I've been fixing them up a little lately and came across this forum. The Newbies cracked me up w/their problems, prompting this post. I know everything about what fails on these bikes and how to fix them. Racing them played a big role in my career as a Mechanical / Reliability Engineer.



I've put up some old (and new, see the trackmaster) Norton stuff on my FB page (if you have access):
http://www.facebook.com/home.php?#/prof ... ef=profile

Can someone tell me how to upload photos here? I have more to share.

Tom
Click to expand...

Hi Tom W,

I remember you and Eric at Laguna Seca BOTT. Thought that was in the mid 80s. I dropped out of the club in '87 and rejoined in '97. I don't see any Norton roadracing in northern California anymore...too bad.
 
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