Crank grinding question

A question for anyone who's had their crankshaft ground -did the shop want the crank assembled or disassembled? A quick check with a straight edge tells me clearance between the flywheel and the inside of the journal is minimal at best if its assembled. Just curious is all.

MikeG said:

A question for anyone who's had their crankshaft ground -did the shop want the crank assembled or disassembled? A quick check with a straight edge tells me clearance between the flywheel and the inside of the journal is minimal at best if its assembled. Just curious is all.

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I ground crankshafts for more than a couple of years , maybe take it in and see what the guy thinks , express your desire to get the radius ground the same , and I would recommend fitting your bearings to your cleaned up parting faces and torqued to correct spec , tell him to grind to suit i:e how much clearance you want say book minimum, which might be .001 - .0015 , the old bearing books which we used to use for all std sizes and tunnel sizes would also give minimum bearing clearance, you'd be surprised how little you can run, I had a mate who bought a V8 crank and one or two B end journals had only .0007 tenths , clearance I gave it a light polish , checked the book and the Forman , and we left it , motor was great , good oil pressure and is still going .you still will need to clean out the crank later . cheers

The guys who used to grind my cranks were AER Speed Grind in Melbourne. When I went there, they were always in the pub next door. All I ever did was tell them the size I wanted the journals to be, and ask them to preserve the radius at their edges. The cranks used to always come back dead on size. I do not think they could grind a disassembled crank.

I always take the crank apart. bolt it back together without the flywheel, then have it ground. That way the shop can access the radius easily. Clean it well, and reassemble. Be sure to mark the flywheel and one side so that it goes back together the same as it came apart.

acotrel said:

The guys who used to grind my cranks were AER Speed Grind in Melbourne. When I went there, they were always in the pub next door. All I ever did was tell them the size I wanted the journals to be, and ask them to preserve the radius at their edges. The cranks used to always come back dead on size. I do not think they could grind a disassembled crank.

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MikeG said:

A question for anyone who's had their crankshaft ground -did the shop want the crank assembled or disassembled? A quick check with a straight edge tells me clearance between the flywheel and the inside of the journal is minimal at best if its assembled. Just curious is all.

Click to expand...

Hi ,
For grinding your crank has to be assembled! you must clean the slug trap out as well after grinding may be best.Get it crack tested as well very comom for them to crack on the main bearings as there is no radius in the corner of the web!

Yes. Mine was cracked on drive side

milfordite said:

I always take the crank apart. bolt it back together without the flywheel, then have it ground. That way the shop can access the radius easily. Clean it well, and reassemble. Be sure to mark the flywheel and one side so that it goes back together the same as it came apart.

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Me too. I was also careful to use tight fit bolts for the top two holes. Not sure if it was necessary, but it seemed like a good idea to me.

Ken

johnm said:

Yes. Mine was cracked on drive side

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Hi you can machine a radius in the face of the web that blends onto the main shaft this can remove the stress riser point and possibly the crack.
I make Billet comando cranks mainly for race engines

Thanks. Yes we have done this to my new second hand crank. About 4 years ago now.

I initially had my crankshaft apart when I took it to the machine shop. Cleaned of course. They requested that it be assembled so I did it right there. They worked their magic and all is well.