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Mail From: (email redacted) (DUHART JOHN)

Hey Greg,



Why would you need to take a crank to a machine shop for grinding? What
are you trying to remove, from a used crank that is no there on a new
crank? I've never done a engine rebuild.



JHD IV





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Mail From: (email redacted) (Ken Boetzer)


> Hey Greg,
>
>
>
> Why would you need to take a crank to a machine shop for grinding? What
> are you trying to remove, from a used crank that is no there on a new
> crank? I've never done a engine rebuild.
>
>
>
> JHD IV

Good afternoon,

We sometimes leave the beginners behind. The grinding process is an attempt to bring
the bearing journal areas back to a condition of roundness and smoothness compatible
with long engine life. As the engine slowly (We hope) wears away the original atoms
it does so in an often nonlinear fashion. This results in out of round and scored
areas on the bearing surfaces of the crank journals. The worn crank is placed in a
specialized lathe for turning. Instead of a single point cutting tool a spinning
grinding wheel is brought to bear against the spinning surface to be trued to spec.
This results in a fresh surface for a new bearing to mate with. Actually the surfaces
float next to each other with a thin layer of oil between a fine running engine and
another addition to the local scrap metal bin. The freshened journal will be a bit
smaller than original (Usually in increments of .010 inches, hence the term 10 under
crank and bearings.) and will be mated with the appropriatly undersize bearing.

Hope this isn't to obscure an explaination,

The geezer speaks out again!

Cheers,

Ken


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Mail From: R John Lye <(email redacted)>

On Jan 17, 5:07pm, DUHART JOHN wrote:
> Why would you need to take a crank to a machine shop for grinding? What
> are you trying to remove, from a used crank that is no there on a new
> crank? I've never done a engine rebuild.

When an engine has been run for quite a while, you'll often find
score marks on the crank journals (usually from dirt passing
through - remember to change that oil!). The machine shop grinds
down the journals to a fresh, clean surface.

Does that make sense now?

John Lye

(email redacted)


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Mail From: (email redacted) (Thomas Augustus Kimberly)



> Try English Spares, (at least I think that's the name) 1-800-241-1916,
> ask for Tom. These guys are somewhere in Georgia, I have dealt with them many
> times and always with good results.

In theory English Car Spares are in the process of turning into a SAAB
bits and pieces place. Last time I was there that is what they told me
and other Brit people about Atlanta have told me that too although they
haven't changed their name yet. I just know that if it ever does happen I
want the huge Union Jack off the front of the building.

-Thomas


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Mail From: "Richard Jackson - Network Technician ext. 2570"
<(email redacted)>


>In theory English Car Spares are in the process of turning into a SAAB
>bits and pieces place. Last time I was there that is what they told me
>and other Brit people about Atlanta have told me that too although they
>haven't changed their name yet. I just know that if it ever does happen I
>want the huge Union Jack off the front of the building.
^^^^^^^^^^

What do you want this for, a ritual burning of it on Independance day :-)

Rich
Northampton
England.

'73 Mk IV Spitfire
'76 1500 Spitfire (In bits) }
'67 1200 Herald Saloon }
'71 13/60 Herald Estate } All un-roadworthy
'69 Morris Minor }
'66 Austin A40 Farina }




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Mail From: (email redacted) (DUHART JOHN)

Thanks for this explanation Ken,



>Good afternoon,

>

>We sometimes leave the beginners behind. The grinding process is an
attempt to bring

>the bearing journal areas back to a condition of roundness and
smoothness compatible

>with long engine life. As the engine slowly (We hope) wears away the
original atoms

>it does so in an often nonlinear fashion. This results in out of round
and scored

>areas on the bearing surfaces of the crank journals. The worn crank is
placed in a

>specialized lathe for turning. Instead of a single point cutting tool a
spinning

>grinding wheel is brought to bear against the spinning surface to be
trued to spec.

>This results in a fresh surface for a new bearing to mate with. Actually
the surfaces

>float next to each other with a thin layer of oil between a fine running
engine and

>another addition to the local scrap metal bin. The freshened journal
will be a bit

>smaller than original (Usually in increments of .010 inches, hence the
term 10 under

>crank and bearings.) and will be mated with the appropriatly undersize
bearing.

>

>Hope this isn't to obscure an explaination,

>





Explains things perfectly. I guess if I'm rebuilding my engine I
should be checking all moving parts with a caliper, and compare them to
original spec. Is there a point where you say, "this part needs fixin",
and "this part has to be replaced". The idea that you could just have a
machine shop grind a part down never entered my mind, I would of just
replaced the part.



Thanks,

JHD IV





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Mail From: Gregory Petrolati <(email redacted)>

On Thu, 17 Jan 2019, DUHART JOHN wrote:

>
> Why would you need to take a crank to a machine shop for grinding?

Here's the short list.

The crank shaft journal is out of round... one must grind
it round again.

polishing the crank so it has less friction as it spins

> What are you trying to remove, from a used crank that is not there on
> a new crank?

Finally, weight. The balancing of a crank shaft for competition or
just better performance usually requires removing weight from
unbalanced areas. The factory balances the crank, but to production
standards, and not with all the spinning parts e.g. flywheel fan
pulley timing gear, etc. They also don't balance to the finer degree
that a reliable machine shop can do. Usually when you balance an
engine, you no only balance the crank and all moving parts on it, you
balance the pistons, and connecting rods as well. these are done
separately so that they conform, in weight, to each other. With
everything balanced, the engine can turn at a higher RPM and more
freely without damage.

Greg Petrolati

(email redacted) 1962 TR4 (CT4852L)
"That's not a leak... My car is just marking its territory!"
Greg Petrolati, Champaign, Illinois



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Mail From: David Rupert <(email redacted)>

BJ Zwizzler,

Just got back into town today, and thought I'd check on that TR4 crankshaft.
Did you have a chance to get it removed and mike the journals? How much do you
want for it? Looking for anything else in trade? Let me know.

David Rupert
(email redacted)
1967 TR4A (rigid axle)
1980 TR7



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