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Stripped Oil Drain/Cracked Case Before & After

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I had a factory service manual for my new bike that was 1 model year off and had a torque value of 20 Lb-ft for the oil drain bolt when it was supposed to be 12 Lb-ft. I tried to torque it and the case cracked. I couldn’t fix it and faced buying a new case from Honda at about $400 and completely disassembling and reassembling the engine to swap them. Instead I found Craig, an expert local welder and he was able to grind out the cracked aluminum and build (weld) the case back up. Then he faced the gasket surface, re-drilled and tapped the hole. He is a true miracle worker. Cost $40. Should have cost twice that easily.crf 450R 008.jpgcrf 450R 012.jpg

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The pic on the left looks like a previous (poor) repair

Its good to know there are still some true engineers out there that can figure out how to fix things beyond a mouse click ;)

Edited by nesc103y
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There should be a little "relief" between the bolt hole and the oil drain just above it so the crankcase oil can be drained completely
The oil doesn't actually come completely out the threaded bolt hole, but drains out from just above it when you remove the bolt.

Edited by HappyG

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There should be a little "relief" between the bolt hole and the oil drain just above it so the crankcase oil can be drained completely

The oil doesn't actually come completely out the threaded bolt hole, but drains out from just above it when you remove the bolt.attachicon.gif1379670909892.jpg

 

Yes I considered that. However, there is also a relief in the magnesium case cover as well that will allow the oil to drain. Cinsidering how weak this area is we decided that no releif in the case itself and the possabilty of a minor delay while draining the oil was worth it to beef up the weak design.

 

John

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The design is only weak when you put more than about 10 ft bls of torque on that bolt. Remember, the thing has almost zero drag in the threads because of the oil. It gets tighter than hell in nothing flat. If youre using anything bigger than a 1/4' ratchet, its too much right there.

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