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Discussion Starter #1
I'm looking at having to replace a cracked crankcase & need a little advice.....


I'm looking at a '01 Deuce that was low-sided @ 1000 miles. The left-side control bracket caught on something when it went down, which twisted the left-side downtube slightly. That twist impact also cracked the forward mounting ear (where the bolt goes through the frame/motor) on the crankcase. It's a hairline crack at the top of the mounting ear, starting from the frame-side edge and extending approx 3/4".

Engine-wise, it looks like the damage has been contained to the left-side case. There is no external oil seepage or holes into the internals... just at the top, left edge of the ear. So it basically munged up the outside of the case, plus the outer primary and foot controls, without damaging any internals.

My question is two-fold ....

first, how much work is it to R&R the crankcase & do I need to replace the entire block, or just the damaged half? I'm not familiar with the TC-B motor.

Second, the frame was slightly tweaked down where the foot control mounting bracket bolts on. There is a barely noticable bend in the left downtube ... and say barely after sighting it with a straightedge. Other than this downtube, the frame is intact.... steering head, swingarm, suspension, etc are all fine. How much is too much bend in a downtube for it to be straightened. Or am I looking at a new frame too?

Thanks for any thoughts on this ....

Jeffery S.
 

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Hard to say.
The Computrack guys can straighten frames without taking the bike apart and the case may be weldable. Depends on the circumstances and the story. The engine almost certainly has to be taken apart down to the cases to weld and remachine the case.
 

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Discussion Starter #4
Thanks for the reply Hippo ...

The story I heard was a lowside at approx 25-30 mph into a ditch (no water involved). A new bike + a new rider ......

I don't mind just replacing the case and/or the frame entirely. I'd be buying this as a keeper, so I want it to be done the right way.

I restore corvettes as a hobby, so the basic mechanicals don't concern me too much.... what I'm worried about is my inexperience with this motor. Can I just replace the cracked side or is it the whole crankcase? Honestly, I'm thinking that I might be able to pull the motor, disconnect the peripherals, slide up the jugs a bit, split the case and replace the bad half with a HD replacement.... leaving the cam-side of the motor intact. Just trying to gauge how dumb an idea that is, you could say.

I'm not as worried about the frame .... if that downtube is bent out 1/4-1/2" I'd be surprised.
 

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Doesn't work that way, the wheels axial play is controlled by the Timken bearings in the left case half and the engine has to be taken down completely from the right side. Still no big deal. Nothing wrong with welded parts either if done correctly.

The results with the Computrack system are better then a brand new frame. Takes all the tolerance stack out of the geometry.
 

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Discussion Starter #6
That's pretty much what I figured it would take to replace it. Just thought I might get lucky. Since I'll be starting from scratch on this motor ... no specialty tools or manuals ... who makes the best service manuals for this motor?

Regarding the possibility of welding it, do you have any recommendations in the Phoenix-area who you would trust to make this type of repair with cast alum? Maybe the case is repairable ... that would mean a lot less work for me.

thanks...
 
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