Crankshaft dismantling stand

Here we have a simple stand that you can use for dismantling and rebuilding the crankshaft, not only on M20's but also most of the BSA pre unit singles. I made this particular one out of box section, but you could just as well make it from  channel or angle iron,  (about 3 inch minimum). I have found that when making these stands that using exact measurements are no good, as when you weld them up they pull slightly, so the best way is to make it around the crankshaft that you have, that way, you are sure that it fits perfectly.  I make these stands from anything I have lying around, and usually you can use the same principle on  many other bikes that have split crankshafts. This particular one cost me 3 for the steel (new) and took me about 10 minutes to knock up  the only thing that helps is a welder, but you could equally drill and bolt one together. The first thing to do is grind into the box  in the centre to clear the main shafts, then weld (or bolt) the bit that goes into the vice, then all you have to do is weld/bolt on the tube or round bar that fits through the holes in the flywheel, I found that  welding these are on is the best way to do it as you can tack weld the tube (which incidentally is a bit of old handlebar)  whilst the crank is sat on the assembly that way you are sure that it is all going to fit together properly. Now you have made the stand! To make the truing clamp you do really need to make this from channel  section,  this part allows you to hold the crank true to within a few thousandths of an inch prior to final truing the threaded bar that I've used in this particular one is 16mm diameter stock studding. When you've made the stand, don't think that you  can instantly true the crank , it takes a little experience, in a couple of weeks I'm rebuilding an M21 crank  and I'll do a step by step "how to do it".

I hope you all find this useful, if you need any more information on making one or any aspect of crank truing please email me at