saving a crankshaft I thought was junk
- Thread starter ponytl
- Start date
this was the crank.. out of a clone that had hundreds of hard laps sometimes 50@ a time.. it was my practice shaft to learn how to build my crank gear turner, and to learn how to move said gear... but I just thought I'd see if my drill press crankshaft turner would allow me to fix this one up...
this was after... took about 20 minutes but much or that was stopping and checking progress and going to courser sandpaper... I usually just super polish... this took going back and using 400 wet dry with wd40 I've never used anything less than 1200 (1200 is usually my starting point) this was 400, 800, 1200, 1500, and red rouge then white,,,
this was after... took about 20 minutes but much or that was stopping and checking progress and going to courser sandpaper... I usually just super polish... this took going back and using 400 wet dry with wd40 I've never used anything less than 1200 (1200 is usually my starting point) this was 400, 800, 1200, 1500, and red rouge then white,,,
this shows my drill press set up... my lower locating point (a pointed acorn nut it is bolted to the wood) it was a license plate nut for my harley, I put grease on the end of the crank that rests here... the other end gets the threaded stud as seen.. it gets chucked in the drill... on it's lowest speed... I use a bungie cord to keep pressure pulling down on the drill press handle...
I cut aprox 3/4" strips of the sandpaper about 4" long... add a couple drops of wd40 to their surface.. and wrap them around the crank journal held in place with a 4" piece of scotch tape... not TOO tight.. turn on the drill press... I use a rubber rim strip off a bike or motorcycle (the rubber band piece that isolates your spoke nuts from your tube) about 20" long...I hold this where it makes one loop around the crank I pull back and forth on the rubber strip as the crank turns.... to polish I sometimes go back with up to 2000 grit... and I have some that is used to polish glass windshields that i do not know what it is...
I "think" everything on the crank was just deposited alum from the rod failing... I had micro polished this crank when the engine was built... so I "think" i just got all the crap off that stuck to the journal..... I checked my notes on when i built it.. just to see how much I had "removed" but same mic... and I got the same reading... and I got it side to side.. center... and at every point... still round... this engine... just slowed down... it did not break the rod... I had no intention of even trying to save it.. had just polished a batch of cranks... and thought why not.... I grew up in a crankshaft shaft shop with bobby rowe so i have been playing with cranks since i was 15 ... was offered all the equipment when they closed up... but that was some tonnage I think it all went to the scrap man.... sad...