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Crankshaft regrinding advice plz.

Here’s where to discuss anything specific about your standard(ish) car or something that applies to the model in general.
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Howard722
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Crankshaft regrinding advice plz.

Postby Howard722 » 24 Jan 2022 12:18

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
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busheytrader
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Re: Crankshaft regrinding advice plz.

Postby busheytrader » 24 Jan 2022 18:52

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

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Re: Crankshaft regrinding advice plz.

Postby dursleyman » 25 Jan 2022 16:08

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.
Russ

1981 TR7 Sprint DHC & 1977 TR7 Sprint FHC
Dursley
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irco
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Re: Crankshaft regrinding advice plz.

Postby irco » 28 Jan 2022 21:47

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.
OAP Tinkerer :D

Howard722
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Re: Crankshaft regrinding advice plz.

Postby Howard722 » 29 Jan 2022 12:49

Thanks for all the input. I hope to avoid the +0.060 if/when the time arrives -cheers
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Beans
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Re: Crankshaft regrinding advice plz.

Postby Beans » 02 Feb 2022 14:53

Carefull with the hardening, it is rather thin
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1976 TR7 FHC (currently being restored ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng)

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