Crankshaft Scoring.

[95'RS-T]

I have a 6 bolt crankshaft that has some scoring on the main journals. I wanted to know if I could still use this crank, maybe get it polished or if I should search for another? Here are some pics, the third main journal looks and feels the worse:
Yeah Its a bit dirty.

 

[jayson427]

Just take it to a machine shop so they can check it out. Its not the best but can probably be reused

 

[BogusSVO]

Yes, That crank needs to be checked out at a machine shop.

Even if it needs ground .25mm/.010 you will be fine.

 

[95'RS-T]

Thanks guys, yeah I just bought a set of standard king rod and main bearings for another 6 bolt crank I have, and I did noticed today that one of the rod journals on that crank has a nice gouge in it right at the oil hole. Although it don't feel that bad it looks like it would destroy My new bearings. Well I guess I'll look for a machine shop and see what they say.

 

[YZFR1]

Just get two (1-2" & 2-3") inch micrometers that can measure down to .0001" and measure it yourself.

Original mains diameter is 2.243"

Original rods diamter is 1.771"

The main things to watch out for are out-of-roud limit of .0006" and taper limit of .0002".

Some scoring should be ok if there are no high spots, that's what can damage your bearings.

A ghetto way of polishing a crank is to put it in an engine block and rotate it on any two mains at a time, a two man job obviously

 

[95'RS-T]

Thank you for them measurements. I'm actually curious about how that method works. Could you PM Me more details, it would sure save me some time instead of pulling another crank from the you pull it.

 

[bastarddsm]

just get it polished and hot tanked. its like $25....

 

[bryanwheat]

Thank you for them measurements. I'm actually curious about how that method works. Could you PM Me more details, it would sure save me some time instead of pulling another crank from the you pull it.

Don't attempt to polish the crank like that. Just pay a machine shop to polish it up for you. Being cheap will cost you a log more in the long run.

 

[95'RS-T]

I agree, the one known automotive machine shop around my area don't polish cranks or even grind them for that matter. I asked how they could even call themselves a machine shop (they hung up on me)! Anyhow there are a couple other "machine shops" I called that are around but they all say they don't do automotive machining. I'm just gonna have to look for a good used one. Thanks again guys.

 

[TSITurbo95]

^^ Agreed. Do it once, do it right, don't cheap out on something as crucial as the crank, yet you should not cut corners on anything, but especially nothing internal wise. . .

95'RS-T check out a place called Warrior Machine in Red Lion, PA, he does EXCELLENT work! He does not answer his phone often, but stop on by and he'll be there.

 

[jayson427]

You can always ship it a good machine shop for cheap if you can't find a good one near you. Like said previously it will save you alot in the long run.

 

[95'RS-T]

Ok thanks for the info man. The only problem is its like a 2 hour drive for me ya know? Although I do plan on building a stroker motor in the future, and when I do I'll have to check him out.

Jayson427; Yeah I could send it out, but with the turn around time and what not I could just get a good used one. I was just trying to cut corners, because I'm a very impatient person! I appreciate your input though.

 

[huafist]

That crank would likely clean up fine with a .010" cut. However, if you can't find a machine shop in your area that you can trust doing it, finding a replacement crank is going to be your best bet.

 

[YZFR1]

So, if he did try to polish the crank himself and then checked it with micrometers for out-of-round and taper, what would he have to lose?? A couple minutes of his time?

 

[BogusSVO]

I agree, the one known automotive machine shop around my area don't polish cranks or even grind them for that matter. I asked how they could even call themselves a machine shop (they hung up on me)! Anyhow there are a couple other "machine shops" I called that are around but they all say they don't do automotive machining. I'm just gonna have to look for a good used one. Thanks again guys.

Alot of smaller machine shops sub contract out the crank work.

A good crank grinding machine will cost $80k for a new cheap one

You can buy a used wore out junked crank grinder for about $10k

Then you have to have a good machinist to run it.

So when you own one, you got to have it running all day to pay for it.

 

[John Mark Dongon]

I have a 6 bolt crankshaft that has some scoring on the main journals. I wanted to know if I could still use this crank, maybe get it polished or if I should search for another? Here are some pics, the third main journal looks and feels the worse:
Yeah Its a bit dirty.

If it's more smooth than scoring, than it should be fine. Use some fine grit sandpaper and shoe lace to help even out the surface if you don't want to take it to the shop. After, apply some polish and make sure it's very clean.