Crank Specs

Are these the correct crank specs for a forged crank:

Rod Journals 49.9 (1.965)
Main Journals 59.9 (2.358)

So if I were to get the crank mains turned I see that the next step bearing is the .25 (0.010) so I would have the mains turned to 59.89 (2.108) that correct.

Oops

Try this instead, Depending how you measure Metric/Standard

Main Bearing Stock Spec: 59.9mm (2.358in)

Next Step Bearing is 0.010mm (0.25in)

So The crank would get turned to 59.89mm (2.108in)

59.9 - 0.010 = 59.89mm
or
2.358 - 0.25 = 2.108in

Is all of that correct!!

I can barely catch the grooves on the crank with my finger nail and it almost looks like it is bearing material stuck to it and not grooves.

Current specs on the crank mains are:

1. 59.97mm (2.360in)
2. 59.97mm (2.360in)
3. 59.99mm (2.361in)
4. 59.99mm (2.361in)

Mains 3 & 4 are the worst, 1 & 2 look like they would just need a polish.

Anyone?!?!?

The machine shop will tell you what they turned it down to, then you order according to make/model, and whatever turn-down they specified. I've never needed to know the exact measurements when ordering bearings...?

SO.... I just send it out, tell them to turn it and then hope they turned it to a spec where someone sells the bearing size for?!?!?

Only two sizes available (0.010mm and 0.020mm - std ) and I don't want to send it off and have them turn it to a size they don't make a bearing for!!

@Em - You guys have a machine shop that you use and trust to get a crank turned/polished? I have not heard back from the one that Chris sent over to me. Need to find one that could do the work around the first of the year or so. The crank would need to have the oil galley balls removed and eitehr replaced or tapped for set screws as It needs to be cleaned as it came from a spun bearing motor

Anyone!!!

Quote:

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Originally Posted by DrGonzo

SO.... I just send it out, tell them to turn it and then hope they turned it to a spec where someone sells the bearing size for?!?!?

Only two sizes available (0.010mm and 0.020mm - std ) and I don't want to send it off and have them turn it to a size they don't make a bearing for!!

@Em - You guys have a machine shop that you use and trust to get a crank turned/polished? I have not heard back from the one that Chris sent over to me. Need to find one that could do the work around the first of the year or so. The crank would need to have the oil galley balls removed and eitehr replaced or tapped for set screws as It needs to be cleaned as it came from a spun bearing motor

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We just send them to our machinist, they machine it to whatever is needed, give us the specs, and we order bearings accordingly. Any machinist can do it really. Just bring it to them, and tell them what you need done. 10, 20, etc is I would assume standard machining intervals, And they just need to mark what the mains and rods are machined at, and you order the bearings accordingly.

You know they have big books on what size your crank is by make, model, year, and displacement.

If you have to tell them anything but the clearance you want you should find somewhere else.

So basically tell the machinist I need to clearance on the mains to be 0.02 - 0.05 mm (.0008 - .0020 in.) after turning the crank???

yeah and they should know that already.