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Thread: best way to remove surface rust on crank

  1. #1
    Hybrid booster mo' parts's Avatar
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    Arrow best way to remove surface rust on crank

    for those of you who have had to deal with this, what was your approach?
    im reassembling a block for the shelby and the crank has some surface rust on it, not the entire thing. its mostly just on about half of the journals.
    i have another one, just in case, but this one is already out of the block. i feel safer putting the orig. crank back in its block, rather than a diff. one. money is somewhat tight, or else id have the machine shop polish it.
    ideas?

    thanks

  2. #2
    Hybrid booster guyd_15's Avatar
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    Re: best way to remove surface rust on crank

    Polish it with green Scotchbrite?

    Guy

  3. #3
    turbo addict Tony Hanna's Avatar
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    Re: best way to remove surface rust on crank

    When it comes to crankshafts, my advice would be to go ahead and drop the coin to have the machine shop do it.

    With that said, if there's absolutely no way to get it done professionally, try the finest grit scotchbrite pad you can find. The millwrights use them at work to clean up shafts that run in pressurized oil bearings (boiler FD and ID fans) and they seem to do a really good job.

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    Re: best way to remove surface rust on crank

    i will see what it cost to have done. anyone have any examples of what they paid to polish a crank? i may just go that route.
    i was told by my dad to use emory cloth then steel wool? i do have some that we use on copper for brazing.....
    it will be a temporary motor, but it will need to make the drive to sdac and back, and keep as a back up motor. im going to build a commonblock for it by winter.

  5. #5
    boostaholic
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    Re: best way to remove surface rust on crank

    I'm with Tony spend the money and take it to a machine shop and have it done. This is a real critical part of the motor. It sure would suck to see it fail early just cause you wanted to save some money $. Think about how much $ you would be out if some thing happened.

  6. #6
    turbo addict Tony Hanna's Avatar
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    Re: best way to remove surface rust on crank

    If the rust is bad enough to need emery, I'd definately look into having it done at a shop. Remember, any polishing/sanding you do on a surface removes material and it's almost impossible to do so evenly by hand. That's extremely important on a journal that has to be perfectly round. If it's just light surface rust, you may get away with the scotchbrite, but if there are any pits, it should go to the machine shop, and will probably need turned. As for having a machine shop polish it, I'd say $20-$40 depending on the shop. Most places will regrind a 4 cyl crank for around $80 so just polishing is going to be a bit less.

  7. #7
    Hybrid booster mo' parts's Avatar
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    Re: best way to remove surface rust on crank

    my shop quoted me 110 to turn my forged crank 10/10. they are charging me 35$ to install int. shaft bearing and a hone. they usally do me pretty good, been going to the same one for years.





  8. #8
    turbo addict Tony Hanna's Avatar
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    Re: best way to remove surface rust on crank

    That looks like you might be able to get away with polishing it with a scotchbrite pad. You're not out much to try, and if you're not satisfied when it's done, you can always take it to the machine shop at that point.

  9. #9
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    Re: best way to remove surface rust on crank

    It is an area where if you don't get it [perfect, you will cause bearing damage.

    I polish cranks at work all the time and it is the only way to do it correctly. We use an old lathe and chuck it up, then have a crank polishing unit that runs a large scotchbrite belt that spins as well. Somethime, you can have raised surface areas that will mess up a bearing in a heart beat which could be caused by rust, or a nick from handling in general (rod removal, installation, etc..)

    If it were a TBI car that you had to get back together for selling it outright, then I'd do it by hand.... but something you want to last and also serve as a performance vehicle, must do it right.
    Quote Originally Posted by 22mopar
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    Hybrid booster 4cefedomni's Avatar
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    Re: best way to remove surface rust on crank

    yo look up rust removal using electrolysis, i was reading about it you get a bucket big enough for the crank to completely fit in it, fill it with water and dump in a box of arm and hammer washing soda, then you get some stainless steel(like shitty cutlery) connect the forks and stuff together in a ring so that it completely surrounds the crank then hook it up to a battery charger or 12 volt power source hook the positive side to the crank and the negative side to the cutlery let it sit until the rust is gone, this method wont damage your machining
    you can't polish a turd! [COLOR="Red"][FONT="Arial Black"][/FONT][/COLOR]13.67@100.11

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    Re: best way to remove surface rust on crank

    too much work, dude!

    Fine scotch brite hand pad using something like wd-40 as well. Go around the journal, not side to side. If any high spots, then you must take it to a machine shop for a quick polish job. Shouldn't cost too much.
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

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  12. #12
    Hybrid booster 4cefedomni's Avatar
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    Re: best way to remove surface rust on crank

    it sounded pretty simple to me and it turns the rust back into your part filling in any pitting caused by it, where the scoth bright pad will remove the rust and leave the pitting. and potentially ruin the machining.
    you can't polish a turd! [COLOR="Red"][FONT="Arial Black"][/FONT][/COLOR]13.67@100.11

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    Re: best way to remove surface rust on crank

    How does it turn rust which is degraded steel back into a nice void free surface finish? Sounds impossible to turn back the hands of time on rust and rebuild the journal via this method. I am sure it removes or disolves the rust.
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

    Steve

    '90 VNT competition package Shadow - T-III SC6262 conversion/restoration
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  14. #14
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    Re: best way to remove surface rust on crank

    well, a little wd-40 and steel wool, using a oil filter wrench strap, i came up with this.....crank has only sat for about 6 months, i should have put it in a bag.




  15. #15
    boostaholic
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    Re: best way to remove surface rust on crank

    It looks pretty good.

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    Re: best way to remove surface rust on crank

    give us a real close up pic.
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

    Steve

    '90 VNT competition package Shadow - T-III SC6262 conversion/restoration
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  17. #17
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    Re: best way to remove surface rust on crank

    best i can do. these shots are of the worst side. im still thinking i may have the machine shop look at it at least. the motor was running fine before, and had excellent oil press. its pretty smooth, nothing to catch a fingernail or anything.




  18. #18
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    Re: best way to remove surface rust on crank

    kinda blurry. From what I see, it may be better to have it given a quick polish job at a shop. I see some imperfections in the finish, but just may be negative impressions fropm what the rust did to it.
    Quote Originally Posted by 22mopar
    have a look at my feedback on the forum. all positive.

    Steve

    '90 VNT competition package Shadow - T-III SC6262 conversion/restoration
    '91 Spirit R/T - white
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    '92 IROC R/T - red
    '67 Barracuda 273 now, 440/727 awaits....

  19. #19
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    Re: best way to remove surface rust on crank

    I would always have a crank polished. Thats a pretty timeless method of engine building unless you have it machined under slightly to use the oversize bearings.
    If you have access to a micrometer big enough to measure the journals measure them in at least 3 places side to side and around to make sure they are true or within factory tolerance of out of round etc.
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  20. #20
    Hybrid booster mo' parts's Avatar
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    Re: best way to remove surface rust on crank

    my machinist said it looked decent, but thought it could use a polish.

    i ended up using some 400, then 600 to polish it my self(like mentioned in the mopar fwd manual) using a rubber strap the width of the journals and polishing in the direction of rotation. she looked beautiful afterwards, better than the last set of picts and plastigauged out at .002 on all main journals and .0015 on the rod journals.
    its in the motor and carrying great oil press. ive got almost 100 miles on it now. this is not a permanent motor, but one i will use till winter when i do build a forged commonblock, then i can put this one on the stand for back up.

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