Easy crank lightening!!

[phil37]

  I've just lightened my 860SF's  starter motor clutch - it's now 150 grams (5+ OZ) lighter - as it spins at engine speed - I'm bound to gain at least another 0.0005BHP!

 

[Paul Marx]

Have you balanced it Phil? 
Paul

 

[Tippie]

Good job, Phil
How thin did you turn down the width?
Have you ever managed to get the 2 parts of one of these apart?
Cheers
Lee

 

[phil37]

Have you balanced it Phil?

Yes Paul - the heavier one tips the scales downwards 

Hi Tippie - Yes - I did this years ago and thinned the O.D too much and had to shrink an aluminium ring round it to stop it opening up! - I also overthinned the thickness and it's a bit too light to give a good inertia on cranking my hi-comp 750 over!
Not that easy to get apart - milled rivet heads flat then drilled a 4mm hole in them to avoid bashing them too hard on removal to make sure I didn't smash the brittle hardened core. I left this thickness at around 3mm I think. You can put it back together with 5mm screws - I countersunk the unit to make sure allen screw heads miss chewing up the dynamo belt. I also thinned the drive cog behind to clear the 5mm full nyloc nuts - Regards - Phil

 

[Tippie]

Thanks. I have one with a plunger firmly stuck and have been trying to get it apart so I can get that out and clean up the other plunger bores. Is a stubborn bastard and I don?t want to break it.

 

[phil37]

Hi tippie - I had two stuck on this one - they were rusted in - I had to drill through spring locater with a small drill to then push the plungers out - replacement ones had holes all the way through - made life easy!! - Regards - Phil

 

[phil37]

Left out the most important part for dismantling - I drilled two 5mm holes 180? apart (you can see one in photo) so that drill just touches the hardened core - then, using a flat ended punch, I carefully tapped out the core a little at a time.