Crankshaft regrinding advice plz.

[Howard722]

The standard data sheets show a maximum regrind allowance of +0.040".
However I see +0.060" shells are also available for both main journals and crank pins-any advice/experience/update on going this extra 0.020" would be good?
Thanks in advance

[busheytrader]

I don’t know myself Howard, however a few years ago I had to have a non Triumph engine reconditioned and I’d recommend the guys at Middlesex Reboring in Lawrence Street, Mill Hill NW7 for their knowledge if they are still there.

Might be worth a call.

Adam

[dursleyman]

Be ok for normal road use but we were always told to avoid too deep a re-grind because it obviously weakens the crank and you will loose the surface hardening unless you get it redone.

[irco]

The correct answer really depends on the use you intend for the engine. As stated above, ok for lower stress road use.
However there was a practice several years ago to offset grind the big end journals to the maximum thereby increasing the stroke of the crank & the cc's of the engine. This was often accompanied by polishing, shot peening, tuftriding then balancing the whole rotating assembly from clutch through to crank pulley. Also balanced rods & pistons. This theoretically smoothed out the engine & improve reliability at higher revs.
So if expense is not an issue, go for it, otherwise stick to minimum necessary regrind to provide a reliable standard engine.

[Howard722]

Thanks for all the input. I hope to avoid the +0.060 if/when the time arrives -cheers

[Beans]

Carefull with the hardening, it is rather thin