SOHC.co.uk Forums > Project Board
1977 400F2 first restore project
smoothoperator:
Thanks so much for the help guys, Tim has me sorted with a matching crank and cases which is fantastic.
sprinta:
--- Quote from: smoothoperator on January 03, 2021, 05:18:35 PM ---Drilled out the engine mounting bolt which was mostly something like body filler until well down to just above the nut. Drilling the actual bolt wasn't too bad as I used a new 11 mm HSS Cobalt bit. 10 mm bit wasn't long enough to give clearance between the drill chuck and the crankcase. I drilled away a good part of the nut also. Anyhow it was all going fine until the bolt was relieved when the end of the nut was reached. I could see cracks open up slowly in front of my eyes, almost in slow motion. Bummer. The end of the bolt was pressed up hard against the crankcase which must have been causing stress. The pictures tell it better than words. First image shows most of the bolt removed before any cracks. 3rd image shows the indentation in the crankcase made by the end of the bolt. Anyhow this leaves me needing replacement crankcases or possibly a welding job? I haven't split them yet as I'm waiting on a clutch nut tool at the moment. Can't wait to see what's inside!
https://photos.app.goo.gl/sHrq2Xko7tHU2FuE7
--- End quote ---
Are you sure they are cracks and not just casting flaws as they all seem to have slightly raised ridges? Pity you did not clean the cases in the area first as if they were they present before drilling you would have seen them?
Laverda Dave:
I found the link to someone who had a similar problem and how they cured it.
http://www.sohc.co.uk/index.php/topic,21245.0.html
smoothoperator:
Crank cases split with some difficulty, the top bolt near the drive sprocket sheared leaving an inch of bolt in the bottom half, this one is exposed and had badly rusted. However once the cases were split the remainder came out OK with mole grips. Inside very grimy but the gears all look good. Crank shells are excellent. Horseshoe completely seized and very worn. Bit more disassembly then cleaning and assessment.
https://photos.app.goo.gl/McKNaChzh5Y7fpNi7
smoothoperator:
Drilled out the broken bolt tensioner from the cam chain adjuster so that I could remove the cam chain bar. This really didn't want to come out. Left a fairly central 6 mm hole in the case so it could be re-threaded if I end up using this case for any reason. The cam chain bar came out in good nick but it was very tight in the hole so probably just needs deburring with a fine grade of emery.
https://photos.app.goo.gl/tk5am6szGwEf8pez5
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