truing up crank

[tavspeed]

hi all,have been trying to true up my crank,run out with the dial guage just in front of the mag bearing track is 1 1/2 thou,down near the woodruff key slot it is 5 thou,where is the best place to measure it,and is the ideal run out of 1 thou measured as far down the tapered shaft as possible,cheers all.

[rosscla]

As I understand it you're supposed to measure the run out at the furthest cylindrical point from the centre as that's where it matters most...

How are you doing the measuring? Can you post some pics please of the jig you're using?

[camel]

if you can wait next edition of scootering is doing an article on this subject

[wack 63]

I do mine both ends and at the keyway and aim to get them around 0.01 -0.02 mm although up to 0.05 is maximum.Sometimes it can take hours to get it right but one I did last week only took 4 whacks with the copper mallet to get to 0.02mm.

[wezly]

Mark Broadhurst has just updated his tech site, with more information on cranks. Might be worth a look?

[tavspeed]

hi all,will try and post pics of the jig tomorrow,have tried adjusting the crank with a rubber mallet,but cant budge it,will get a copper one from work monday.i am thinking quite a bit of movement of the crank cheek,would show as a couple of thou on the taper,so 5 thou is quite misaligned.
my dialguage is imperial,whats .001mm in thou's.

[tavspeed]

just had a look at mb's tech site,i see they use 2 dial guages,where i have only one,and they are measuring at the furthest point,good stuff mb.

[rosscla]

hi all,will try and post pics of the jig tomorrow,have tried adjusting the crank with a rubber mallet,but cant budge it,will get a copper one from work monday.i am thinking quite a bit of movement of the crank cheek,would show as a couple of thou on the taper,so 5 thou is quite misaligned.
my dialguage is imperial,whats .001mm in thou's.

0.001mm is 0.0000397" ...approx 4 hundred thousandths of an inch...that's tight tolerances

I do mine both ends and at the keyway and aim to get them around 0.001 -0.002 mm although up to 0.005 is maximum.Sometimes it can take hours to get it right but one I did last week only took 4 whacks with the copper mallet to get to 0.002mm.

@wack63 0.005mm max?...thats 0.000196" ...less than 2 ten thousandths of an inch???

should those figures be imperial???

[tavspeed]

this is my jig i made,2 angles with vee's cut in them,one welded to the plate,the other loose,but clamped solid with the clamp,i could run the crank on the seal faces,but didnt want to risk damaging the faces.[/phhttp://i1144.photobucket.com/albums/o490/tavspeed1610/S7301321.jpg?t=1329038415otobuckvid]

[tavspeed]

try this